Polyarylates macromolecular coils

Kozlov, G. V Shustov, G. B. Dolbin, L V Structural memory of the polyarylates macromolecular coil fractal analysis. Proceedings of XVII Mendeleev s Congress by General and Applied Chemistry Achievements and Perspectives of Chemical Science. Kazan, 21-26 October 2003, p. 442. 

Table 16.3 Comparison between the fractal dimensions (D) calculated by two methods for macromolecular coils of polyarylates ...

TABLE 4 The comparison of macromolecular coil fractal dimensions calculated by different methods, for polyarylates. 

However, besides the indicated factors, that is, A6 and C, the other parameters can influence on value. In Fig. 32, the dependence Dy(Ad) for polyarylates PD and PF is adduced. As one can see, this dependence breaks down into two curves, in addition one from them includes PAr with rigid para-connections in the main chain (the polyarylates PF-2 and PF-7, Table 5, p. 120 in Ref. [5]) and the other—polyarylates with less rigid metha-connections. The indicated plot demonstrates again the importance of such characteristic as polymer chain rigidity for determination of value of macromolecular coil in solution. 

FIGURE 32 The dependences of macromolecular coil fractal dimension on difference of polymer and solvent solubility parameters A8 for polyarylates with metha-( 1) and para-connections in the main chain. 

The change of the fractal dimension D with temperature reflects the corresponding changes in sizes, degree of compactness and asymmetiy of shape of a macromolecular coil in solution [89]. The importance of the temperature dependence of study is determined by strong influence of this parameter on the processes of synthesis [28], catalysis [90], flocculation [91], so forth. At present as far as we know experimental evaluations of the temperature dependence of a macromolecular coil are absent. Theoretical estimations [13] suppose that the temperature enhancement makes the fractal less compact, that is, leads to Devalue reduction. Therefore, the authors [92] performed the experimental study of dependence on temperature for the macromolecular coils of polyarylate F-1 [5] in diluted solutions and evaluation of change influence on s nithesis processes. 

The polyarylate (PAr) on the basis of phenolphthaleine and dichlora-nhydride of isophthalic acid (F-1) [5] were used. Tetrachloroethane, N, N-dimethylformamide, tetrahydrofuran and 1,4-dioxane were used as solvents. As it is known through Ref [89], the reason of changes in the structure of a macromolecular coil in diluted solution with temperature variation can be both the effects of long-range interaction (excluded voliune effects) and the effects of short-range interaction leading to the specific influence... 

In Fig. 40, the dependences of on testing temperature T have been shown for F-1 solutions in tetrachloroethane and N, N-dimethylfomiamide (c=0.5 mass %). As one can see, Z) monotonous increasing at Tgrowth is observed, that is, macromolecular coil compactness degree enhancement is realized. The plots of Fig. 40 extrapolation to D=2.0 [10] allows one to estimate 0-temperature values for the indicated solvents. Let us note, that the achievement of 0-conditions does not mean any critical state of the macromolecular coil. Such state forthe coil in diluted solution (practically isolated macromolecule) can be reached at the fractal dimension critical value F /, determined by the Eq. (4) of Charter 1. As it follows from tiie indicated relationship, 2.285. Let us note, that approximately at this Devalue the dependence [ti](2) for polyarylate F-1 in tetrahydrofiuan (Fig. 38) becomes parallel to abscissa axis, that is, this Devalue is a critical one. 

FIGURE 52 The dependence of glass transition temperature on macromolecular coil fiactal dimension in tetrachloroethane for copolymers polyarylate-polyarylenesulfonoxide. The points—experimental data the straight line—calculation according to the Eqs. (14) of Chapter 1 and (95)-(97). 

FIGURE 55 The dependence of macromolecular coil fractal dimension on polymer and solvent solubility parameters difference A8 for polyarylate F-2. 1—calculation according to the Eq. (4) 2—calculation according to the Eq. (11) 3—a calibrating curve. 

The fractal dimension Dj values, calculated with the Eqs. (11), (48) and (103) using, are presented as a function of A8 in Fig. 55, from which their satisfactory correspondence with the calibrating curve follows, excluding for F-2, synthesized in hexane. D j. values are also adduced in Table 16, from which Dj and Dj variation tendencies identity follows. Let us note, that the dimensions and >/ were received for two different groups of polyarylate F-2 the first was received for the same polymer, but was measured in different solvents, the second was received for different pol miers actually (synthesized ones in different solvents), but measured in the same solvent. Their identity supposes, that the macromolecular coil formation in s Tithesis process submits to the same laws, as dissolution, that is, controlled by the same groups of factors and dimension is determined according to the same Eq. (11). 

FIGURE 57 The dependence of mean-viscous molecular weight A/ on macromolecular coil fractal dimensions (1) and Dj (2) for polyarylate F-2. 

TABLE 17 The characteristics of polyarylate F-2 macromolecular coil in different solvents. 

Kozlov, G. V Temiraev, K. B. Shustov, G. B. The intercommunication of stmcture of macromolecular coil in solution with stmcture and properties of linear polyarylates condensed state. Proceedings of Higher Educational Institutions, North-Caucasus region, natural sciences, 1999,3, 77-81. 

Kozlov, G. V Shustov, G. B. Fractal analysis of the structural memory of macromolecular coil of polyarylates. Reports of Adygskoi (Cheikesskoi) International Academy of Sciences, 2007, 9(2), 138-141. 

As it has been shown above, polymers macromolecular coils in solution are fractal objects, i.e., self-similar objects, having dimension, which differs from their topological dimension. The coil fractal dimension Dp characterizing its structure (a coil elements distribution in space), can be determined according to the Eq. (4). The exponent ax values for polyarylate Ph-2 solutions in three solvents (tetrachloroethane, tetrahydrofuran and 1,4-dioxane) are adduced in [36]. The values ar] for the same polyarylate are also given in paper [37]. This allows to use the Eq. (4) for the macromolecular coil of Ph-2 Devalue estimation in the indicated solvents. The estimations showed D variation from 1.55 in tetrachloroethane (good solvent for Ph-2) up to 1.78 in chloroform. As it is known [38],... 

TABLE 1 Comparison of the macromolecular coil fractal dimensions Dp obtained by different methods, for polyarylate Ph-2, synthesized in different solvents [33],... 

TABLE 5 The characteristics of macromolecular coil of polyarylate Ph-2 in different solvents. 

The condition is chosen by two reasons. Firstly, used at Ph-2 synthesis C(, values are relatively small and for diluted solutions the value grows as and in the limit of very diluted solutions [90], Secondly, at the obtained for polyarylate Ph-2 values D =1.65 in dichloroethane and D=1.81 in acetone [87] macromolecular coils density is large enough and exceeds density of surrounding them solution [88], These densities become equal at reaction cessation, as it was noted above. Since for the same polymer then for MM reaching reac-... 

Accounting for said above appreeiation the authors [113] demonstrated principal possibility and expediency of the considered physical principles application for nonequihbiimn polycondensation description on the simplest example of polyarylate Ph-2 synthesis in solution. The macromolecular coil fractal dimension D j. value was determined according to the Eq. (4) and spectral dimension d — according to the Eq. (39). The estimations have shown, that D =1.55 and d =1.0, from which it follows, that in the considered conditions Ph-2 is a typical linear polymer [72]. 

FIGURE 34 The dependence of macromolecular coil fractal dimension D. on polycondensation process duration t for polyarylate Ph-2. 

As the first approximation the authors [132] supposed, that the smallest stirring intensity (500 rpm) did not deform macromolecular coil to some extent significantly and therefore the value for polyarylate D could be determined in that case according to the Eq. (4). In its turn, the dimension ds for swollen coil with excluded volume interactions appreciation can be determined according to the Eq. (39). 

The fractal dimension Df of macromolecular coil in solution with excluded volitme effects appreciation was determined according to the Eq. (39). Since all the considered polyarylates are linear polymers, then for them the spectral dimension is ds = 1.0 [72]. The gelation transition or transition from solution up to the condensed state is characterized by macromolecitlar coil environment change and now instead of solvent molecules it is in similar coils environment. This results to fractal dimension change and now its value df for the condensed state is determined according to the eqiration [17] ... 

FIGURE 61 The dependence of glass transition temperature on macromolecular coil fractal dimension for polyarylates of series Ph (1) and D (2). The curve is theoretical calculation, the points are experimental data. 

Let us also note, that the structure of a macromolecular eoil in synthesis process defines to a considerable extent the received polymer molecular weight. In Fig. 57 the dependence of mean-viscous molecular weight on value for polyarylate F-2, S5mthesized in different solvents is adduced. values were received with the aid of Maik-Kuhn-Houwink equation for solutions in tetrachloroethane [5], As one can see, the systematic reduction at growth, obtained by both considered above methods, is observed. increase means coil larger compactness andp smaller values. Both these factors should result in formation of aggregates with smaller sizes large number [131], that is, inM reduction. 

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