Polymer Science, Ser. C, Vol. 44, No. 1, 2002, pp. 83 - PDF document

83 Polymer Science, Ser. C, Vol. 44, No. 1, 2002, pp. 83Ð99. Translated from Vysokomolekulyarnye Soedineniya, Ser. C, Vol. 44, No.Original Russian Text Copyright © 2002 by Volynskii, Arzhakova, Yarysheva, Bakeev.English Translation Copyright © 2002 by /InterperiodicaÓ (Russia). INTRODUCTIONSolvent crazing of polymers constitutes a certain Faculty of Chemistry, Moscow State University, This work was supported by the Russian Foundation for BasicResearch, project no. 99-03-33459a, the Program ÒUniversitiesof Russia,Ó project no. 015060206, and the NWO FoundationE-mail: volynskii@mail.ru 84 POLYMER SCIENCEVol. 44 VOLYNSKII Upon a further tensile drawing, the nucleated crazespropagate in the direction perpendicular to the directionof tensile drawing, and the width of the growing crazesmicron) (the stage of craze tip advance). This processproceeds until individual growing crazes or theirThen, the next stage of solvent crazing commenceswhen the as-grown crazes begin to increase their dimen-sions along the direction of tensile drawing (the stage ofcraze thickening or craze widening). Evidently, at thisoriented (Þbrillar) nanoporous state takes place.Upon the solvent crazing of polymers in the pres-ence of AAM, another stage exists: when most of thethe collapse of the as-formed porous structure takesplace [5]. This Þnal stage of solvent crazing is accom-ent crazing is accom-surface [1]. The mechanism of collapse has been dis-cussed at length in [8]: as was shown, this stage of sol-vent crazing is controlled by the natural draw ratio ofpolymer, as well as by the properties of AAM andAll stages of solvent crazing are accompanied by thedevelopment and evolution of the microscopic porosityin the solvent-crazed polymer. The whole process wasdescribed in more detail in [9]; here, we will onlysile strain of the solvent-crazed polymer (Fig. 2). As fol-lows from Fig. 2, at the early stages of tensile drawing,the volume porosity increases, and this increase is relatedto the nucleation and further growth of crazes. However,at relatively high tensile strains, the above-mentionedcollapse of the porous structure of the polymer takestotal porosity of the sample. As a result, the dependencePROPERTIES OF THE SOLVENT-CRAZED POLYMER MATRIXÐLIQUID LOW-MOLECULAR-MASS COMPONENT SYSTEMS Tensile drawing axisII is the stage of craze tip advanceCraze matterUndeformedFig. 1. Schematic representation of various stages of solvent crazing in polymers: I is the stage of craze nucleation,II is stage of craze tip advance, III is the stage of craze widening (thickening), and IV is the stage of craze collapse. POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES simplest way (by the tensile drawing of polymer sam-ples in the presence of AAM). When the sample isremoved from AAM, and the low-molecular-mass liq-uid is allowed to evaporate from the volume of crazes(in this case, the sample is kept either in a free state orunder isometric conditions), various crucial phenom-ena take place; the above behavior is provided by thevided by theevaporation of even high-volatile liquids is retarded dueto the speciÞc features of the structural organization ofthe solvent-crazed material. Under such conditions, theevaporation of the low-molecular-mass componentmay last over many weeks [14]. The above phenomenaare especially interesting for the solvent-crazed sam-ples with high tensile strains as achieved upon the ten-sile drawing of polymer in the presence of AAM whenthe collapse of the porous structure in crazes occurs. Asappears to be efÞciently encapsulated in the polymerstructure. Therefore, the liquid low-molecular-masscomponent appears to be preserved in the polymered in the polymerWhen the solvent-crazed sample is loaded with aviscous nonvolatile liquid, even more fascinating phe-nomena are observed [15, 16]. Figure 3 shows theweight loss curves for PET samples containing a non-volatile liquid component (glycerol) which was intro-duced into the polymer structure via solvent crazing. Asover many months and even years. The rate of this pro-cess is controlled, in particular, by the nature of the liq-uid component and polymer, the geometry of the testsample, and the conditions of tensile drawing. It isimportant to mention that, in the case studied, we dealpatible low-molecular-mass liquid. It is this incompati-systems. The slow rates of the above processes may beexplained by the fact that the diameter of microvoids induced low-molecular-mass liquid. As a result, a certainfraction of the nonvolatile low-molecular-mass compo-nent, which was introduced into the polymer structurevia solvent crazing, may be preserved in the polymerfor an indeÞnitely long period of time. Actually, thisimplies that the solvent crazing of polymers may betreated as a certain mode of microencapsulation of low-molecular-mass liquid components in the polymerlow-molecular-mass component in the incompatible-mass component in the incompatibleSOME APPROACHES TO PREPARATIONOF NANOCOMPOSITES BASED ON SOLVENT-CRAZED POLYMER MATRICES AND THEIR CHARACTERISTICSAn important feature of solvent crazing concernsthe fact that micropores formed in the structure of agrowing craze are efÞciently Þlled with the surroundingliquid medium. In turn, the introduction of the low-molecular-mass component into the nanoporous crazestructure is accompanied by its dispersion down to thecolloidal dimensions. As a result, solvent crazingallows one to achieve a high level of mutual dispersioncontaining the incompatible low- or high-molecular-mass component. As the dimensions of craze Þbrils andmicropores between them are equal to ~1Ð100 nm, onemay conclude that they correspond to phase dimensionsporous structure of the solvent-crazed polymer, poly-






    Fig. 2. drawing of PET in AAM.
      Time, hWeight loss Fig. 3. solvent-crazed PET samples containing glycerol (thetensile drawing of initial PET Þbers was performed in25% alcohol solution in glycerol). Tensile strain: 86 POLYMER SCIENCEVol. 44 VOLYNSKII ces containing low-molecular-mass substances may beTherefore, the tensile drawing of the polymer in thepresence of an appropriate liquid medium via solventcrazing makes it possible to deliver the thermodynami-cally incompatible low-molecular-mass component tothe polymer and to provide its dispersion down to theNote that the approach of solvent crazing enablesthe introduction of almost any low-molecular-masscompounds into the polymer structure. The tensiledrawing of polymers in the presence of a liquid, whichserves as a target additive by itself (a low melting tem-perature of the low-molecular-mass component), or inan AAM solution containing the dissolved target low-molecular-mass component, provides the only neces-sary condition. In the Þrst case, the low-molecular-mass compound serves by itself as AAM at elevatedtemperatures (however, evidently, at temperaturesbelow the glass transition temperature or the meltingtemperature of the deformed polymer). As a result, thetensile drawing of the polymer in the melt of this com-pound proceeds via the mechanism of solvent crazing,tallization of the low-molecular-mass component takeslow-molecular-mass component is crystallized in itsIn the second case, the solution of the target additivein AAM is introduced into the volume of crazes. Uponfurther evaporation of the volatile component, in situcrystallization of the dissolved target component in thepores of the solvent-crazed polymer proceeds. Evi-dently, the volume of crazes may be Þlled with the low-molecular-mass substances with almost any meltingy meltingBoth methods involve the direct introduction of thelow-molecular-mass compounds into the volume ofcrazes; therefore, hereinafter, this mode of introductiondirect method.Obviously, there are many substances that mayhardly be introduced into the solvent-crazed polymervia the above procedure. For example, one may men-tion metals, many metal salts, metal oxides, and otherinorganic compounds. In this case, the polymerÐlow-molecular-mass compound systems may be preparedtion). Hereinafter, this method of preparing polymerof the introduction of low-molecular-mass compoundsDirect Method of the PreparationThe pioneering studies on the introduction of low-vent crazing were performed for the system composed-octadecane (OD) (C) [20]. The polymer sample was stretched in theoperating clamps. As a result, the porous structure ofcrazes was Þlled with OD, which is an efÞcient AAM,tion in the polymer matrix took place. This simple50 wt % and more of the low-molecular-mass compo-nent to be prepared. The amount of the introduced low-molecular-mass component would be controlled by thelevel of the volume porosity and would depend on theevolution of the polymer porous structure upon its ten-sile drawing in AAM (Fig. 1). Independently of the ten-sile strain of polymer samples upon solvent crazing, thelow-molecular-mass component appears to be dis-persed to Þne aggregates, and the dimensions of suchaggregates are comparable to the dimensions of poresThe preparation of the above nanocomposites not onlyoffers new routes to develop a new class of promisingadvanced materials based on the solvent-crazed poly-mers but also provides an efÞcient means to character-The speciÞc features of phase transitions of low-molecular-mass compounds in the volume of crazes.The DSC method offers a tool of obtaining informationconcerning the state of low-molecular-mass com-pounds in the narrow pores. Figure 4 presents the typi-cal DSC curves for the crystallization of OD in a freestate and in the porous structure of PET. As followsfrom the DSC scans, the crystallization of the hydrocar-C; this process mani-fests itself as a nonsymmetric endothermic peak. Thelatter observation is likely to be related to a transitionfrom a rhombic to hexagonal packing which takes placein the temperature region of melting; this behavior istypical of saturated hydrocarbons [21]. At the sametime, OD incorporated into the solvent-crazed polymermatrix shows some earlier unknown speciÞc features inits thermophysical properties. As is seen in Fig. 4(curve), the crystallization appears to proceed via twostages. First, one may observe the transition whichtakes place at a temperature corresponding to the tran-exothermic peak at a temperature that is 6Ð8C lowerthan the melting temperature of the free OD. As is wellseen, the principal contribution (~80%) to the heat ofcrystallization is provided by a wide low-temperature POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES The reasons for the above difference may beexplained when studying the removal of OD from theporous structure of the solvent-crazed PET sample byrinsing. Figure 5 presents relative changes in the weightagainst the time of its treatment with -hexane. As iswashed out from the structure; however, a marked frac-tion of OD is still preserved in the polymer. Figure 6shows the DSC curves for the crystallization of OD in-hexane fordifferent periods of time. As is seen, the Þrst fraction,which is removed from the sample, is the fraction of(Fig. 6, curves and ual removal of the fraction of OD, which provides thelow-temperature wide crystallization peak, is seen(curves ). Even though, upon a prolong rinsing, alltemperature transitions in the PETÐOD system arefaded, and the corresponding X-ray reßections in X-raypatterns disappear, a marked fraction of OD is still pre-served in the polymer sample (Fig. 5).Evidently, the high-temperature crystallization peakis provided by a certain low amount of OD which islocated on the surface of the sample in macroscopicrelief grooves or in large pores. Naturally, thermophys-(curve ) and 6). A wide low-temperature crystalliza-tion peak is likely to be related to the fraction of OD,crazes. The above decrease in the crystallization tem-perature is provided by changes in the transition tem-formed crystallization nucleation centers. According tosmaller the nucleation center or the length of the regionof a new phase, the lower the corresponding crystalliza-tion temperature. By the value of supercooling, oneter upon crystallization of the free-standing OD. Thisvalue was estimated from the DSC data to be equal to; that is, this value is comparable to the porehigher than the effective size of the most pores in thestructure of the solvent-crazed PET. The dimensions ofthe crystallizing phase are limited by pore walls, and itsation center in the free OD. As a result, the crystalliza-aggregates takes place at much lower temperatures.Taking into account the fact that the pore size distribu-tion of the solvent-crazed polymers is rather wide, thelow-temperature crystallization peak appears to berather extended along the temperature axis. This obser-vation allows the above phenomenon to be applied forthe analysis of typical pore size distributions in the sol-vent-crazed polymer as prepared by the tensile drawingin the presence of a given AAM. The related calculationprocedure was presented in [20]. Figure 7 presents theresults of the above calculation as pore size distribu-tions for the solvent-crazed PET samples, which were  Fig. 4. The DSC curves for crystallization of () OD in the crazes of PET. The
   Time, minWeight loss Fig. 5. Weight loss in the OD-containing solvent--hexane. 88 POLYMER SCIENCEVol. 44 VOLYNSKII prepared by the tensile drawing in the presence of ODto a tensile strain of 50 or 400%. As is seen, as the ten-sile strain is increased, one may observe a markeddecrease in the effective pore diameter which may beestimated from the depression in the crystallizationtemperature. This result agrees with the above specula-tions concerning the evolution of the porous structure inthe polymer upon its tensile drawing in the presence ofHowever, it seems evident that the above pore sizedistributions may hardly provide a detailed and ade-quate description of the porous structure of the solvent-crazed polymer. As follows from Figs. 5 and 6, when,sponding X-ray reßections are faded out, the sampleAs was shown in [20], the fraction of the unwashed ODvent-crazed sample and achieves rather high values(~25 wt %). The above evidence suggests that the sol-vent-crazed polymer with high tensile strains containsappreciable amounts of inner microvoids which areinaccessible for the solvent; therefore, the incorporatedlow-molecular-mass compound cannot be completelyremoved from the polymer via solvent extraction. Thisin crazes as is shown in Fig. 1. At the same time, theabove closed microvoids appear to be so small that theencapsulated OD may hardly form a continuous crys-show no phase transitions. The corresponding X-raypatterns also show no X-ray reßections which are typi-cal of the crystalline structure of OD. In other words, acertain fraction of the low-molecular-mass componentdevelopment of a continuous crystalline phase isimpossible. Therefore, this offers an interesting oppor-gates below which the thermodynamic term becomes incorrect. As follows from Fig. 7, for OD, this 
Hence, the introduction of low-molecular-massorganic compounds into the polymer stretched in thepresence of AAM allows one to gain additional infor-mation concerning its porous structure. Taking intoaccount the fact that the low-molecular-mass compo-nent is dispersed to the Þne aggregates (tens of aggre-gates) in the polymer matrix, this offers an experimen-tal opportunity to investigate the speciÞc features ofAs was shown in subsequent studies, the above spe-ciÞc features of the phase transitions of low-molecular-mass compounds in solvent-crazed polymer matricesshow a general character. These features (widening inphase transitions and shift to a low-temperature region)are observed for various low-molecular-mass com-pounds (hydrocarbons, fatty acids, and alcohols) andfor various solvent-crazed polymers (PET, HDPE, PP,PA, PTFE, PMMA, PVC) [22Ð28]. Evidently, this gen-eral character of the above phenomena is related to theus mention that the above behavior is reported for the  Fig. 6. DSC curves for OD-containing PET samplesafter their washing with -hexane for (
     Fig. 7. Pore size distribution curves for the solvent-crazed PET samples obtained by tensile drawing inolation to the x-axis gives the size of the critical POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES solvent-crazed polymers prepared via the mechanismof both classical and delocalized solvent crazing [1].This is due to the fact that, in this case, the effectivepore dimensions, rather than the morphological organi-zation of the as-formed porous structure, play the keyrole. For both modes of solvent crazing, the character-; that is,they correspond to the region of typical colloidaldimensions. This fact is responsible for the principalfeatures of the phase transitions of low-molecular-massIn addition to the above-mentioned thermophysicalbehavior of low-molecular-mass compounds in thecraze structure, let us discuss the following aspects. Forsitions, their crystallization in narrow pores is charac-terized by their own speciÞc features. For example, thephase composition of low-molecular-mass compoundsinvolved in porous polymer matrices was studied by theas studied by thecurves for a normal hydrocarbon, heneicosane (HE), ina free state and in the crazes of various polymer matri-ces. The appearance of two peaks in the DSC scans(curvefree-standing HE from the to Curves show a single wide high-temperature peakwhich corresponds to the melting of HE in crazes.Therefore, one may conclude that, in the crazes of var-ious polymer matrices, HE exists only in the cation. Similar results concerning the existence of thehigh-temperature modiÞcation of the low-molecular-mass compound in crazes have been obtained for tride-coic acid (TDA) and cetyl alcohol (CA) [25, 27]. In allcases, the incorporated component involved in theporous polymer structure exists in its high-temperaturecompound, but in its free state at room temperature.A high stability of modiÞcations of the low-molec-ular-mass compounds, which are unstable in their freelevel of dispersion in the microporous structures. Inmicropores, all polymorphic transitions may take placeonly in the temperature interval where the radius of thecritical nucleation center of the low-temperature phaseis lower or equal to the pore radius. When the tempera-within the temperature interval wherein the rate of for-mation of a new phase is rather high, no polymorphictransitions take place and only the high-temperaturepolymorphic modiÞcation of the low-molecular-massAs was shown above, the low-molecular-mass com-pounds crystallized in the micropores of solvent-crazedoriented polymer matrices exist in a highly dispersestate. Therefore, the analysis of their phase transitionsshould be conducted taking into account the surfacepotentials (free energy, enthalpy, entropy). Let uspresent the thermodynamic potentials of the low-molecular-mass compound as the sum of volume andsurface components. Then, taking into account the factthat, upon the polymorphic transition, the speciÞc sur-face of the system remains unchanged, one may deriveequations which describe variations in speciÞc surfacepolymerÐlow-molecular-mass compound boundary, aseters of the melting process of the low-molecular-massmelting of the low-molecular-mass compound but alsoits crystallization in the porous polymer matrix. Thisfact has been convincingly proved when studying theprocesses of melting and crystallization of TDA in thecrazes of the solvent-crazed PET samples by the DSCmethod (Fig. 9). Crystallization of the low-molecular-mass component in the micropores of the solvent-  Fig. 8. DSC melting curves of HE in (and in the solvent-crazed samples of () PA-6, and () PET. 90 POLYMER SCIENCEVol. 44 VOLYNSKII critical nucleation center from the experimental ther-low-molecular-mass compound in polymer matricesTo verify the applicability of the advanced thermo-sitions of low-molecular-mass compounds in thethe solvent-crazed structure (the dimensions of crazesmall-angle X-ray scattering. Table 1 presents the com-parison of the above results with the correspondingDSC data [28, 29]. A fair agreement between the valuesobtained by various methods is achieved, and this factprovides a convincing evidence for the applicability oftransitions of low-molecular-mass components in theHence, the introduction of the low-molecular-masssubstances into the porous structure of solvent-crazedhighly disperse state. Upon transition of the low-molec-ular-mass compounds to the highly disperse state, themarkedly changed. The analysis of phase transitions ofthe low-molecular-mass compounds in the polymermatrices and in the free state illustrates a marked effectbehavior and enables one to gain knowledge of thestructure of pores in the volume of crazes, as well as ofthe state of the low-molecular-mass component in nar-row pores.tion of low-molecular-mass compounds in the vol- The above-described thermal propertiesof low-molecular-mass compounds introduced into thetheir crystallization in narrow pores (1Ð30 nm). Suchthe structural organization of crazes. The parallelthe direction of the tensile drawing appears to be ratherimportant (Fig. 1). This implies that the narrow asym-metric pores separating the individual craze Þbrils alsoappear to be mutually oriented along the direction of thetensile drawing of the polymer. A well-pronouncedasymmetry of the craze structure should also exert a cer-tain effect on the crystallization of low-molecular-masscompounds in the craze volume.This effect was revealed and characterized whensolvent-crazed polymerÐlow-molecular-mass compo-po-As was found, independently of the polymer matrix andnent, the crystallization of the low-molecular-massnon for the solvent-crazed PET containing various low-molecular-mass compounds. As is well seen, the crys-tallization of the above substances leads to the develop-The above phenomenon shows a general characterand is observed when crystallizable (PET, PC) andamorphous polymers (atactic PMMA) are used as poly-mer matrices [18, 19]. All the above features are pre-  Fig. 9. DSC curves for (') melting of TDA (the crazes of PET.PETÐHE8.06.0/6.5PETÐTDA10.57.0/5.0PCÐTDA29.07.0/5.0PA-6ÐCA8.34.6/7.0Note:Numerator and denumerator presents the data of SAXS andpressure-driven liquid permeability, respectively. POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES served when either ionic or molecular crystals are intro-duced into the solvent-crazed polymer matrices.Even though the orientation of low-molecular-massthe polymerÐlow-molecular-mass compound pair.In [22Ð29], numerous nanocomposites based on vari-ous solvent-crazed polymers and incorporated long-chain fatty alcohols, hydrocarbons, and acids have beenstudied. The crystallization of such compounds ispatterns becomes much easier. The analysis of X-raypatterns shows that a set of pointlike meridional, equa-torial, or diagonal reßections may be attributed to theX-ray scattering from the oriented layered planes [27].planes of the low-molecular-mass compounds relativeto the direction of the tensile drawing of polymers areshown as and , respectively. The inclined order of the-carboxylic acids is shown as ^.Table 2 lists the interplanar distances and the characterof orientation of low-molecular-mass compounds in thepores of various solvent-crazed polymers. For compar-As follows from Table 2, all the above low-molecu-lar-mass substances appear to be oriented upon theircrystallization in the polymer matrices. For the linearhydrocarbon, HE, and CA, the layers are oriented per-pendicular or parallel to the direction of tensile drawingalso show an inclined orientation of crystalline layers Fig. 10. X-ray patterns of the solvent-crazed PET samples containing (a) KI and (b) OD and (c) solvent-crazed PCsample containing TDA. Direction of tensile drawing  Fig. 11. 92 POLYMER SCIENCEVol. 44 VOLYNSKII Polymer matrixOrientationin polymerin free state*HEHDPE28.828.65(28.528.92(CAHDPE45.437.37(45.443.83(45.444.9(Undecanoic acidHDPE26.125.68(25.930.16(Dodecanoic acidHDPE27.731.2(27.727.42(TDAHDPE29.735.35(29.730.0(Pentadecancoic acidHDPE35.740.2(35.635.8(35.834.4(*The corresponding structural modiÞcation of the component is given in brackets. POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES The orientation of low-molecular-mass compoundsupon their crystallization in narrow (~10 nm) asymmet-ric pores of solvent-crazed polymer matrices is prima-the low-molecular-mass compound in crazes, intercrys-tallite surface energy is minimum. The character of theorientation of low-molecular-mass compounds in poly-mer matrices is controlled by the minimum free energyof the surface component at the polymerÐlow-molecu-lar-mass compound boundary. Therefore, each mode ofentation and is characterized by its characteristic valueof surface energy.As was shown in [29, 30], there is a common reasonof the low-molecular-mass compound in the polymermatrix. This reason concerns the presence of innerstresses in solvent-crazed polymer samples. It is impor-tant to note that, depending on the level and direction ofcrystalline lattice of the low-molecular-mass com-The orienting effect of the highly developed struc-zation of ordinary low-molecular-mass compounds.This effect is also seen for the phase transitions in LCcompounds. For example, phase transitions of -butox-ybenzylidene aminobenzonitrile in the crazes of vari-ous polymers were studied in [31]. As was shown, thiscompound also appears to be oriented in the narrowpores of the solvent-crazed polymers. Such an orienta-duced into the porous structure of the solvent-crazedpolymer matrices are oriented with a high level ofordering which may be reversibly changed upon phaseIndirect Introduction of Low-molecular-mass Compounds into the Structure of Crazes As was mentioned above, only the limited range oflow-molecular-mass compounds can be introduced intothe volume of crazes via the direct method. Evidently,the direct method is unable to provide the introductionof substances, which are insoluble in AAM, as well ashigh-melting substances at temperatures below theof the deformed polymer. Nevertheless, the above poly-mer-based compositions containing metals, semicon-ductors, ferroelectrics, and other target additivespresent an evident interest from the practical viewpoint.Therefore, new approaches were developed to the prep-mer matrix (in situ reactions). Actually, in this case, thenanophases with a required level of dispersion and agiven morphology. The development of nanometricvoids makes it possible to utilize them as Òmicroreac-torsÓ for various chemical reactions (reduction,exchange, etc.). This approach to the preparation ofnanocomposites offers a solution to various fundamen-due to a limiting effect of pore walls and a high level ofreaction in situ in the structure of the solvent-crazedpolymer was described in [19]. That reaction presentedthe structure of the solvent-crazed PET. To this end, thePET Þlm was stretched in an alcohol-containing aque-ous solution of potassium iodide. As a result of suchtensile drawing, 25 wt % KI was introduced into thepolymer. Then, the as-crazed Þlm was placed into thealcohol-containing aqueous solution of silver nitrate.As a result, the crystals of silver iodide were precipi-tated in the polymer structure. Then, the as-preparedsample was kept in a solution of a standard photo-graphic developer. Upon such a treatment, silver iodidedecomposed to a metallic silver. All stages of this pro-tion of the low-molecular-mass component upon in situreactions. For example, at the Þrst stage, the crystalliza-tion of KI is accompanied by the formation of a well-deÞned orientation, whereas, at the second stage, silverthe precipitated silver is completely isotropic.The applicability of the above method of introduc-the viewpoint of the loading of the craze volume withthe low-molecular-mass component. Actually, as theconcentration of an inorganic compound in AAMincreases, the content of the low-molecular-mass com-pound in the porous structure of crazes after the solventevaporation increases [32]. Nevertheless, it is quite evi-dent that this approach does not allow a complete load-ing of the porous polymer, as it takes place upon thetensile drawing of the polymer in the melt of the low-molecular-mass compound. Even for highly solublesubstances such as KI in alcohol-containing aqueoussolutions, the content of the inorganic component in thesample does not exceed 30Ð50 wt % [32]. Figure 12demonstrates the SEM image of the solvent-crazedthe sample shows a well-pronounced open porousstructure. Then, the sample was placed into the satu-rated alcohol-containing aqueous solution of KI andkept there for a week. Evidently, upon such a prolongedtreatment, AAM in the porous sample is replaced by aÞlm containing 47 wt % KI was prepared. Potassium 94 POLYMER SCIENCEVol. 44 VOLYNSKII iodide is precipitated from the saturated solution inm, and the crystals are randomly distributed inthe pores. The dimensions of such small-sized crystalsare not uniform, and this reßects rather random charac-ter of their precipitation from the solution. Figure 12vividly shows that, even though the craze structure isÞlled with the saturated KI solution, most crazes appearto be free of the low-molecular-mass component.At the same time, the level of the polymer porositydeveloped upon its tensile drawing in AAM is known tobe rather high. The tensile drawing of glassy polymerssample are primarily provided by the development ofporosity when the contributions from other modes ofplastic deformation are negligibly small. A trivial esti-mation allows one to conclude that the complete load-ing of pores in the solvent-crazed sample with a tensilestrain of 100% by the low-molecular-mass compound should provide aweight gain of 300 wt % with respect to the weight ofTo overcome the above disagreement and to achievea high level of loading of the porous structure of the sol-vent-crazed polymer with an inorganic compound, themethod of countercurrent diffusion has been applied[33]. This method of the introduction of low-molecular-mass compounds is different from the above approach.In this case, the solvent-crazed polymer Þlm, that is, thepolymer Þlm with an open-porous structure, is placedcomponents which are able to react with each other.Low-molecular-mass compounds diffuse toward eachother and react directly in the pore volume of the mem-brane and the chemical reaction takes place in thepores; as a result, the porous structure of the solvent-crazed polymers appears to be efÞciently loaded as wasshown in [18, 32].Let us illustrate the above approach with the classi-cal photographic process used in [18]. To this end, thesolvent-crazed PET sample was placed into the dialysistaining aqueous solutions of AgNO, from one side,and NaCl, from the other side. After staying in the dial-ysis cell for one day, the sample was released, rinsedwith water, and dried; the as-prepared sample was stud-Figure 13 shows the SEM image of the solvent-crazed PET Þlm containing AgCl. As is well seen, theprecipitation of the low-molecular-mass component isdramatically different from the above process. As fol-lows from Fig. 13, at the center of each craze, one mayobserve only one crystal of AgCl with a height ofm; the width of this crystal is equal to a distancebetween the craze walls. Hence, this approach makes itpossible to achieve an efÞcient loading of the craze vol-ume with the low-molecular-mass inorganic com-pound. The as-prepared nanocomposition containsappreciable amounts of the highly disperse inorganicNow, let us conduct the photographic process in theof AgCl and the precipitation of the metallic silver. Tothis end, the PET sample with the structure as shown inFig. 13 was allowed to stay in the standard developerfor 2 days. Then, the sample was dried and examined bythe SEM method. The resultant SEM images are pre-As is seen, upon the treatment of AgCl by the devel-oper, the Þne crystals of the metallic silver are precipi-tated in the volume of crazes. Such crystals are charac-that of the initial AgCl crystals. At the same time, the Fig. 12. SEM image of the solvent-crazed PET sam-ple with a tensile strain of 100% after staying in the Fig. 13. SEM image of the solvent-crazed PET sam-of AgCl via the countercurrent diffusion. POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES analysis of the decomposition of AgCl allows one toclarify the problem concerning the interaction of thegrowing crystal with the Þbrillar craze structure. As fol-lows from Fig. 14, Þne silver crystals are located onindividual craze Þbrils and, in some cases, a speciÞcbeadlike structure is formed. This observation suggeststhat the craze Þbrils are involved in the crystallinestructure of AgCl (Fig. 13) rather than expelled from it.Further, numerous studies were devoted to the prep-aration of various nanocomposites based on differentpolymers (PP, PE, PA-6, etc.) and metals and metaloxides via the method of countercurrent diffusion [34Ð41]. In particular, metal-containing polymers wereobtained by the countercurrent diffusion of the salts ofium borohydride. As was found, the above procedureshows a universal character and allows the preparationof various nanocomposites. Such nanocomposites maybe processed as Þlms; the resultant materials are char-ical of the initial polymer matrices. The as-preparedcomposites exhibit various morphological forms. Thistent of the low-molecular-mass disperse phase, its com-pactness, and the level of dispersion but also to governure 15 schematically shows some possible modes forthe location of the low-molecular-phase in the polymerÞlm. Evidently, all the above-mentioned factors arethe as-prepared nanocomposites (for example, electricconductivity, dielectric permittivity, mechanical char-In addition to the above methods, let us discussanother universal approach of metal precipitation frommetal compounds via electrolysis. This approach hasThis approach hasmetal-containing polymer blends based on solvent-crazed polymers. The procedure was the following. Thesolvent-crazed polymer Þlm was placed onto a graphitethe metal salt solution. The controlled voltage was gen-erated using the second electrode which was alsoimmersed in the solution. As the cathode was coveredtook place in the pore volume of the polymer matrix. Inthis way, various solvent-crazed polymer matrices(PVC, PET, HDPE, PP, etc.) were loaded with differentmetals (Cu, Ni, Fe, Co, Ag, etc.).matrix may be controlled by varying the time of elec-tial polymer sample. Depending on the mode of solvententlocated in the individual narrow zones, crazes, or maypolymer matrix. For example, Fig. 16 presents the SEMimages of the solvent-crazed PET samples before andafter their treatment in the electrochemical cell. As isseen, this approach allows one to Þll the porous struc-ture of crazes from the top to bottom of the Þlm. As inthe method of the countercurrent diffusion, the metalinvolved in the craze volume is not monolithic but is Fig. 14. SEM image of the solvent-crazed PET sam-ple with a tensile strain of 100% after the introductionof AgCl via the countercurrent diffusion and the sub-sequent treatment by the photographic developer. Fig. 15. Schematic representation of various types of the introduction of the low-molecular-mass component into thesolvent-crazed polymer matrices via the countercurrent diffusion. The comments are given in text. 96 POLYMER SCIENCEVol. 44 VOLYNSKII dispersed in the polymer matrix. As was mentionedabove, the pore dimensions, which control the size ofTherefore, the above evidence proves the feasibilityof the loading of the porous matrix of the solvent-crazed polymer by almost any target additives in thehighly disperse state. The amount of the introducedadditive may be more than 300 wt % with respect to theweight of the unÞlled polymer matrix. The preparationof such compositions opens a new avenue for the devel-opment of new types of complex polymer-basedThe metallic Þller in the craze volume is not mono-lithic, but occurs in the highly disperse state in theporous polymer matrix. The diameter of pores, as mea-sured by the method of liquid permeability, is 5Ð10 nm.matrix, as follows from the X-ray data, range from 12TECHNOLOGICAL ASPECTS OF THE PREPARATION OF MULTICOMPONENT POLYMER MATERIALS BASED ON SOLVENT-CRAZED POLYMERSThe introduction of various low-molecular-massadditives into polymers presents an important techno-logical problem because, in practice, raw polymerswithout target additives are not used. In this connection,solvent crazing may be considered as a universal meansfor the introduction of modifying additives into poly-consider a well-known process of dyeing of textileÞbers. As is known [47], Òdyeing consists of a sponta-neous transfer of the dyestuff from the solution to theÞber until an equilibrium is attained. The rate of dyeingand the concentration of the dyestuff in Þbers are con-trolled by the laws of the activated diffusion andsoprtion.Ó In the case of a hydrophobic (polyester) Þber,tially, the Þber is imbibed with a slightly thickened dis-(thermosol process) or the Þber is exposed to trichloro-ethylene vapors (vapokol process)Ó [47]. Evidently,here, a uniform introduction of the dye in the cross sec-tion area of the Þber presents a key problem.In this context, let us consider some speciÞc featuresof solvent crazing in the presence of bicomponent liq-uid media. It is important to mention that, upon solventby the porous structure but also by a well-developedinterfacial surface because the dimensions of structuraldreds of angstroms. Solids with a well-developed inter-facial surface are referred to as sorbents. Actually, sol-vent-crazed polymers appear to be nonspeciÞc poroussorbents [48Ð50]. The very fact of adsorption presentsan undoubtedly fascinating phenomenon as it directlyproves the presence of the well-developed interfacialsurface in the solvent-crazed polymers. In this case, oneshould also mention that the sorptional experimentsprovide an opportunity to assess the parameters of theporous structure of solvent-crazed polymers and tocharacterize their evolution upon tensile drawing in thepresence of AAM. To this end, various sorbates withdifferent molecular dimensions are used [48Ð50].Figure 17 shows the results of the related sorptionalstudies as performed for the two sorbates as the weightgain (sorption) plotted against the tensile strain of sol-vent-crazed polymers. Actually, this evidence allowsthe characterization of the surface accessibility of thepores in the solvent-crazed samples for sorbing mole-cules with different dimensions. As is well seen, for thesorbing agent with minimum molecular dimensions 
of tensile strains. At low tensile strains of solvent- 
  Fig. 16. SEM image of the solvent-crazed PET sample (a) before and (b) after the introduction of metallic copper via POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES because, upon solvent crazing, the interfacial surfaceof ~150% (for PET), structural collapse takes place,and this process is accompanied by a marked decreasein the interfacial surface area of the sample [1]. The col-lapse of the porous structure is also observed in the cor-responding sorption curves when the gain in weightlevels off with increasing the tensile strain of the sol-vent-crazed polymer. As the molecular dimensions of (for organic dyeRhodamine B), the curves describing the weight gainplotted against the tensile strain of the solvent-crazedsamples appear to be somewhat different. As is wellseen, at tensile strains above ~150%, the sorption ofObviously, this decrease in sorption is related to the factthe sorbate molecules are unable to penetrate the vol-conclude that, upon solvent crazing, the developmentthat, at early stages of tensile drawing, the pores arelarge and, hence, accessible both for the small-sizedmolecules of AAM and bulky molecules of the targetadditive. At the Þnal stages of solvent crazing, the porefraction of the solvent is expelled to the surrounding,and the big-sized molecules of the modifying additivepolymer sample. Upon a continuous tensile drawing ofthe polymer in the presence of AAM, the as-formedporous structure gradually passes all the above-men-tioned stages of solvent crazing. On the whole, theinteraction of the polymer with the solution of the low-molecular-mass additive in AAM may be presented asfollows (Fig. 18) [51]. At the early stages of the tensiledrawing of the polymer in the presence of the solutionof the modifying additive in AAM (Fig. 18a), the as-developed porous structure is continuously Þlled withthe surrounding liquid medium. The stage of the porouscules of the modifying additive appear to be entrappedpure AAM is expelled into the surrounding medium (axpelled into the surrounding medium (a)The principal difference between solvent crazingand the above traditional approach [47] is the follow-ing. The traditional method is based on a spontaneoustransfer of the molecules of the modifying additive tothe polymer via diffusion. According to the deÞnitionby Rusanov [53], solvent crazing provides Òa forcedÓdelivery of the modifying additive dissolved in AAM toa continuously developing nanoporous polymer struc-as-introduced additive may be much higher than theconcentration of the same additive but introduced viaan equilibrium sorption from the same solvent [1].The above results allow the phenomenon of solventcrazing to be regarded as a universal means for theintroduction of various modifying additives to poly-mers. This approach is based on the quite unorthodoxmechanisms of delivery and immobilization of modify-ing additives in the polymer structure. In this case, theadditive is delivered not by diffusion but via a far morefast mode of transfer through a viscous ßow. To immo-bilize (to Þx) the additive in the structure of a polymerÞber, the polymer and low-molecular-mass componentdo not necessarily have to contain active functionalgroups which are capable of any mutual interaction.The immobilization of the additive in the polymerstructure is provided by the mechanical entrapment ofthe low-molecular-mass component when the molecu-       Tensile strain, %  Fig. 17. vs. the tensile strain of the solvent-crazed PET sam-ples (AAM is propanol). (weight gain). Fig. 18. Schematic representation of structural rear-rangements taking place upon the tensile drawing ofthe polymer via the mechanism of solvent crazing inthe bicomponent liquid medium. The arrows show thedirection of mass transfer of the low-molecular-masscomponent at the different stages of solvent crazing. 98 POLYMER SCIENCEVol. 44 VOLYNSKII lar dimensions of the additive are comparable to thepore dimensions in the polymer structure. Taking intoaccount this reasoning, the range of the target additivesmay be unlimitedly widened. For example, solventcrazing makes it possible to color such hydrophobicpolymer as PP by water-soluble vat dyestuff.As an important feature of the preparation of thecompositions based on solvent-crazed polymers, let usmention the fact that the solvent crazing of polymers ismers. This deformation serves as the basis for the tech-nological process of orientational drawing of polymers,polymers Þbers and Þlms. Evidently, such an importantstage as orientational drawing is implemented in anaccomplished technological solution. Presently, inindustry, various high-strain rate machines are used,and orientational drawing of Þlms and Þbers is per-formed under a continuous technological regime. Inprinciple, the modiÞcation of polymers via solventcrazing implies that the stage of orientational drawingof the introduction of modifying additives. To this end,the orientational drawing of polymers in the solution ofthe modifying additive in AAM should be performed insuch a way that the traditional technological schemeshould be complemented by a rather trivial unit asshown in Fig. 19. In this connection, numerous and suc-cessful attempts [54, 55] have been made to implementthe process of solvent crazing under a continuousregime. In other words, the technological concept ofsolvent crazing allows the preparation of nanocompos-characteristics, on one hand, and various valuable prop-erties (electric conductivity, ßame retardancy, electro-static properties, etc.) as imparted by the target addi-tives, on the other hand. Let us emphasize that suchnanocompositions may be prepared on an existing tech-nological equipment under a continuous regime at high1.Volynskii, A.L. and Bakeev, N.F., , Amsterdam: Elsevier, 1995.2.Yarysheva, L.M., Lukovkin, G.M., Volynskii, A.L., andBakeev, N.F., khimicheskoi mekhaniki. Sb. Nauchn. Tr. (Progress inColloid Chemistry and Physicochemical Mechanics),Shchukin, E.D., Ed., Moscow: Nauka, 1992.3.Sinevich, E.A., Ogorodov, R.P., and Bakeev, N.F., 1973, vol. 212, no. 3, p. 1383.4.Volynskii, A.L., Aleskerov, A.G., and Bakeev, N.F.,Vysokomol. Soedin., Ser. B, 1977, vol. 19, no. 3, p. 218.5.Volynskii, A.L., Aleskerov, A.G., Grokhovskaya, T.E.,and Bakeev, N.F., Vysokomol. Soedin., Ser. A, vol. 18, no. 9, p. 2114.6.Volynskii, A.L., Loginov, V.S., and Bakeev, N.F.,Vysokomol. Soedin., Ser. B, 1981, vol. 23, no. 4, p. 314.7.Yarysheva, L.M., Shamolina, T.A., Arzhakova, O.V.,Mironova, A.A., Gerasimov, V.I., Volynskii, A.L., andBakeev, N.F., Polymer Science, Ser. A, 1998, vol. 40,8.Volynskii, A.L., Arzhakova, O.V., Yarysheva, L.M., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1989, vol. 31,9.Yarysheva, L.M., Volynskii, A.L., and Bakeev, N.F.,Polymer Science, Ser. B, 1993, vol. 35, no. 7, p. 1000.10.Volynskii, A.L. and Bakeev, N.F., Vysokomol. Soedin.,Ser. A, 1975, vol. 17, no. 7, p. 1610.11.Volynskii, A.L., Gerasimov, V.I., and Bakeev, N.F.,Vysokomol. Soedin., Ser. A, 1975, vol. 17, no. 11,12.Volynskii, A.L., Kozlova, O.V., and Bakeev, N.F.,Vysokomol. Soedin., Ser. A, 1986, vol. 28, no. 10,13.Volynskii, A.L., Shelekhin, A.B., Bekman, I.N., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1988, vol. 30,14.Volynskii, A.L., Shitov, N.A., Yarysheva, L.M.,Ukolova, E.M., Lukovkin, G.M., Kozlov, P.V., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1986, vol. 28,15.Volynskii, A.L., Arzhakov, M.S., Karachevtseva, I.S.,and Bakeev, N.F., Polymer Science, Ser. A, 1994, vol. 36,16.Yarysheva, L.M., Karachevtseva, I.S., Volynskii, A.L.,and Bakeev, N.F., Polymer Science, Ser. A, 1995, vol. 37,17.Kalinina, O. and Kumacheva, E., Macromolecules,2001, vol. 34, no. 18, p. 6380.18.Volynskii, A.L., Grokhovskaya, T.E., Shitov, N.A., andBakeev, N.F., Vysokomol. Soedin., Ser. B, 1980, vol. 22,19.Volynskii, A.L., Shitov, N.A., Chegolya, A.S., andBakeev, N.F., Vysokomol. Soedin., Ser. B, 1983, vol. 25,   Fig. 19. Schematic representation of the unit for ori-entational drawing for the modiÞcation of polymerÞlms and Þbers via solvent crazing: is the polymerÞlm or Þber, is the bath Þlled with the active liquidmedium (possibly, containing the dissolved additive), are feed and draw rolls. POLYMER SCIENCEVol. 44 STRUCTURE AND PROPERTIES OF LOW-MOLECULAR-MASS SUBSTANCES 20.Volynskii, A.L., Grokhovskaya, T.E., Lukovkin, G.M.,Godovskii, Yu.K., and Bakeev, N.F., Vysokomol. Soedin.,Ser. A, 1984, vol. 26, no. 7, p. 1456.21.Kitaigorodskii, A.I., (MolecularCrystals), Moscow: Nauka, 1971.22.Moskvina, M.A., Volkov, A.V., Grokhovskaya, T.E.,Volynskii, A.L., and Bakeev, N.F., Vysokomol. Soedin.,Ser. A, 1984, vol. 26, no. 11, p. 2369.23.Moskvina, M.A., Volkov, A.V., Volynskii, A.L., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1984, vol. 26,24.Moskvina, M.A., Volkov, A.V., Volynskii, A.L., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1985, vol. 27,25.Moskvina, M.A., Volkov, A.V., Volynskii, A.L., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1985, vol. 27,26.Volkov, A.V., Moskvina, M.A., Volynskii, A.L., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1987, vol. 29,27.Moskvina, M.A., Volkov, A.V., Grokhovskaya, T.E.,Volynskii, A.L., and Bakeev, N.F., Vysokomol. Soedin.,Ser. A, 1987, vol. 29, no. 10, p. 2115.28.Moskvina, M.A., Volkov, A.V., EÞmov, A.V., Volyn-skii, A.L., and Bakeev, N.F., Vysokomol. Soedin., Ser. B,1988, vol. 30, no. 10, p. 737.29.Volkov, A.V., Moskvina, M.A., Arzhakova, O.V., Volyn-skii, A.L., and Bakeev, N.F., J. Therm. Anal.vol. 38, p. 1311.30.Volynskii, A.L., Moskvina, M.A., Volkov, A.V., andBakeev, N.F., Polymer Science, Ser. A, 1997, vol. 39,31.Moskvina, M.A., Volkov, A.V., Volynskii, A.L., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1989, vol. 31,32.Volynskii, A.L., Grokhovskaya, T.E., Shitov, N.A., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1982, vol. 24,33.Volynskii, A.L., Yarysheva, L.M., Arzhakova, O.V., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1991, vol. 33,34.Moskvina, M.A., Volkov, A.V., Zanegin, V.D., Volyn-skii, A.L., and Bakeev, N.F., Vysokomol. Soedin., Ser. B1990, vol. 32, no. 12, p. 933.35.Stakhanova, S.V., Nikonorova, N.I., Zanegin, V.D.,Lukovkin, G.M., Volynskii, A.L., and Bakeev, N.F.,, 1992, vol. 34, no. 2, p. 175.36.Stakhanova, S.V., Nikonorova, N.I., Lukovkin, G.M.,Volynskii, A.L., and Bakeev, N.F., Vysokomol. Soedin.,Ser. B, 1992, vol. 33, no. 7, p. 28.37.Stakhanova, S.V., TroÞmchuk, E.S., Nikonorova, N.I.,Rebrov, A.V., Ozerin, A.N., Volynskii, A.L., andBakeev, N.F., Polymer Science, Ser. A, 1997, vol. 39,38.Stakhanova, S.V., Nikonorova, N.I., Volynskii, A.L., andBakeev, N.F, Polymer Science, Ser. A, 1997, vol. 39,39.Nikonorova, N.I., Stakhanova, S.V., Volynskii, A.L., andBakeev, N.F., Polymer Science, Ser. A, 1997, vol. 39,40.Nikonorova, N.I., Stakhanova, S.V., Chmutin, I.A., Tro-Þmchuk, E.S., Chernavskii, P.A., Volynskii, A.L., Pono-marenko, A.T., and Bakeev, N.F., Ser. B, 1998, vol. 40, no. 3, p. 75.41.Nikonorova, N.I., TroÞmchuk, E.S., Semenova, E.V.,Volynskii, A.L., and Bakeev, N.F., Ser. A, 2000, vol. 42, no. 8, p. 855.42.Volynskii, A.L., Yarysheva, L.M., Lukovkin, G.M., andBakeev, N.F., , 1992, vol. 34, no. 6,43.Volynskii, A.L., Yarysheva, L.M., Ukolova, E.M.,Kozlova, O.V., Vagina, T.M., KechekÕyan, A.S.,Kozlov, P.V., and Bakeev, N.F., Vysokomol. Soedin.,Ser. A, 1987, vol. 29, no. 12, p. 2614.44.Volynskii, A.L., Yarysheva, L.M., Shmatok, E.A.,Ukolova, E.M., Arzhakova, O.V., Lukovkin, G.M., andBakeev, N.F., Dokl. Akad. Nauk SSSR, 1990, vol. 310,45.Yarysheva, L.M., Shmatok, E.A., Ukolova, E.M.,Lukovkin, G.M., Volynskii, A.L., Kozlov, P.V., andBakeev, N.F., Vysokomol. Soedin., Ser. B, 1990, vol. 32,46.Volynskii, A.L., Shmatok, E.A., Ukolova, E.M., Arzha-kova, O.V., Yarysheva, L.M., Lukovkin, G.M., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1991, vol. 33,47.MelÕnikov, B.N., Entsiklopediya polimerov (Encyclope-dia of Polymers), Moscow: Sovetskaya Entsiklopediya,1972, vol. 1, p. 1135.48.Volynskii, A.L., Loginov, V.S., PlatŽ, N.A., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1980, vol. 22,49.Volynskii, A.L., Loginov, V.S., PlatŽ, N.A., andBakeev, N.F., Vysokomol. Soedin., Ser. A, 1981, vol. 23,50.Volynskii, A.L., Loginov, V.S., and Bakeev, N.F.,Vysokomol. Soedin., Ser. A, 1981, vol. 23, no. 5, p. 1059.51.Volynskii, A.L., Loginov, V.S., and Bakeev, N.F.,Vysokomol. Soedin., Ser. A, 1981, vol. 23, no. 5, p. 1031.52.Volynskii, A.L., Loginov, V.S., and Bakeev, N.F.,Vysokomol. Soedin., Ser. A, 1981, vol. 23, no. 3, p. 567.53.Rusanov, A.I., Abstracts of Papers, 3 Mezhdunarodnayakonf. ÒKhimiya vysokoorganizovannykh veshchestv i (3 Int. Conf.ÒChemistry of High-Organized Substances and Funda-mentals of NanotechnologyÓ), St. Petersburg, 2001,54.Guthrie, R.T., Hirshman, J.L., Littman, S., Suck-E.J., and Ravenscraft, P.H., US Patent 4001367,55.Bakeev, N.P., Lukovkin, G.M., Marcus, I., Mikou-chev,A.E., Shitov, A.N., Vanissum, E.B., and Volyn-skii, A.L., US Patent 5516473, 1996.