142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

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154 K. Ito, S. Kawaguchi where l –1 is the Kuhn segment length (=2q), z is the conventional excluded-volume parameter for the Kratky-Porod (KP) chain, and B is the excluded-volume strength (=b/a' 2 ) for the KP chain with a' being the bead spacing. The YSS theory with the Domb-Barrett function [78] for the a s 2 is applied to the experimental data of z and M w in Fig. 4. It is seen that the experimental values in 3´10 5
Poly(macromonomers), Homo- and Copolymerization 155 Table 2. Glass transition temperatures of PSt polymacromonomers MW of macromonomer 10 Tg of polymacromonomer/˚C –3Mn 10 –3Mw obs. cal. a 0.81 0.9 56–68 44 2.9 3.1 84–90 84 12.4 13.1 98 96 14.0 14.6 100 97 27.0 28.1 – 98 a Calculated by Eq. (18), based on Tg =T g ¥ - 1.0´10 5 2Mw with T g ¥ =100 Therefore, their bulk properties are expected to be significantly different from those of the corresponding linear polymer. Indeed, detailed studies by Tsukahara et al. [31, 83] revealed that the glass transition temperature, T g , of PSt polymacromonomers from 24 is predominantly determined by the excess free volume effect of end group per unit MW, as summarized in Table 2. Generally, the T g value was found to increase with increase of the MW of macromonomer and also that of polymacromonomers. The chain end effect on the glass transition temperature is described by the relation [84] (18) where T g ¥ is Tg for the polymer of infinite MW, M 0 and M are the MWs of monomeric unit and the macromonomer, v m is the free volume per monomeric unit, and v is the excess free volume at a chain end. The value of T g of the polymacromonomers calculated by Eq. (18) is given in Table 2. Hatada and Kitayama [33] also reported that the value of T g of it-PMMA polymacromonomer from 25 (n=30) is 44 ˚C. Tsukahara et al. [83] have reported that when PSt polymacromonomers are cast onto Teflon or glass plates, many cracks are generally created during the solvent evaporation and the resulting films are too brittle to handle. They ascribed the result to a lack of chain entanglement networks in the polymacromonomers [85]. In fact the SAXS profiles of the polymacromonomers in the bulk state demonstrated that the polymacromonomer molecules exist independently of each other [86, 87]. Such behavior was confirmed directly by STM [88] and tapping scanning force microscopy [89]. The incompatibility was also observed between high MW linear polystyrene and PSt polymacromonomers with high degree of polymerization, in spite of the fact that they are athermally mixing [85, 90, 91]. The PSt polymacromonomers have been reported to form lyotropic main chain liquid crystals in toluene solution and in the bulk state [82, 90, 91]. The crystallization behavior of PEO comb-shaped polymers from 27b was reported by Wesslén et al. [92]. The polymacromonomers from n=9 and 23 were amorphous material with T g=–55~–60 ˚C but those from n=45 were crystalline with mp= 38–44 ˚C.
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142 Advances in Polymer Science Edi
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Branched Polymers I Volume Editor:
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Volume Editor Dr. Jacques Roovers I
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Preface While books have been writt
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Contents Synthesis of Branched Poly
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Synthesis of Branched Polymers by C
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72 N. Hadjichristidis, S. Pispas, M
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100 N. Hadjichristidis, S. Pispas,
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Page 137 and 138: Poly(macromonomers): Homo- and Copo
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Dendrimers and Dendrimer-Polymer Hy
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Author Index Volumes 101-142 Author
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Author IndexVolumes 101-142 231 Dun
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Author Index Volumes 101-142 233 Ka
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Author Index Volumes 101-142 235 Og
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Author Index Volumes 101-142 237 Su
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Subject Index Addition-fragmentatio
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Subject Index 241 Microphases 11z,
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