Poly , side chain-type

Poly(benzimidazole) can be used as the reactive polymer for the preparation of side chain-type polyrotaxane via the alkylation on nitrogen. Osakada et al. showed that deprotonation of poly(benzimidazole) followed by N-alkylation with alkyl bromide-terminated pseudorotaxane consisting of 2,3,6-trimethyl-/1-cyclodextrin gave a novel side chain-type polyrotaxane (Scheme 38) [206]. Poly(benzimidazole) having a long -hydroxyalkyl group as the side chain can form an inclusion complex with 2,3,6-trimethyl-/l-cy-... 

Fig. 4 Molecular structure of side chain type LC poly(siloxane) with PEO moiety...

The texture of polymeric chiral liquid crystalline phases. The chiral liquid crystalline phases include the chiral smectics and the chiral nematic or cholesteric phase. Poly(7-benzyl-L-glutamate) and derivatives of cellulose are popular examples of polymers that form a chiral mesophase. Side-chain type copolymers of two chiral monomers with flexible spacers of different, lengths and copolymers of one chiral and the other non-chiral mesogenic monomers may also form a cholesteric phase (Finkelmann et al., 1978 1980). In addition, a polymeric nematic phase may be transformed to a cholesteric phase by dissolving in a chiral compound (Fayolle et al., 1979). The first polymer that formed a chiral smectic C phase was reported by Shibaev et al. (1984). It has the sequence of phase transition of g 20-30 Sc 73-75 Sa 83-85 I with the Sc phase at the lower temperature side of Sa- More examples of Sc polymers are given by Le Barny and Dubois (1989). 

The structures of the polymers used are shown in Figure 1. Side-chain-type polymers, except poly(A -vinylcarbazole) (PVK), were synthesized by radical polymerizations of the corresponding monomers, and main-chain-type polymers were synthesized by the nucleophilic substitution reactions of the corresponding difluoro compounds and diphenols. All the polymers were purified at least three times by reprecipitation into methanol. The details of the syntheses will be published elsewhere. 

The functional architecture of this class of PHA copolymers is substantially different from that of more familiar types of PHAs, such as poly[(/ )-3-hydroxybutyrate] (PHB) homopolymer or poly[(/ )-3-hydroxybutyrate-c<9-(/ )-3-hydroxy valerate] (PHBV) copolymer. The size of the side groups in the conventional PHAs is limited only to short-side-chain types with no more than two carbon atoms. Although PHAs with only one or two carbon side groups may be viewed essentially as linear polymers, PHA copolymers with mcl side groups belong to a broad class of moderately branched polymers. The inclusion of a small amount of mcl-3HA units into the PHA polymer backbone leads to some profound changes in important physical properties of this class of copolymers. 

Zhu J, Shao K, Zhang G, Zhao C, Zhang Y, Li H, et al. Novel side-chain-type sulfonated hydroxynaphthalene-based poly(aryl ether... 

Zhang Q, Gong F, Zhang S, Li S. Novel side-chain-type cardo poly(aryl ether sul-fone) bearing pendant sulfoalkyl groups for proton exchange membranes. J Membr Sci 201 l 367(l-2) 166-73. 

E and F). The essential difference in the main-chain structure between the two types of polyrotaxanes causes large differences in their physical or mechanical properties. Polyrotaxanes A-D are further divided into main- (A and B) and side-chain type (C and D). Meanwhile, the synthesis of poly[2]rotaxane (E) and poly[3]rotaxane (F) has been very recently achieved. Genuine poiyrotaxane seems to be one of the polyrotaxanes like the latter topological polyrotaxanes, which may reflect their truly unique structures to their properties. 

Scheme 12 Stoddart s side-chain-type poly[2]catenane.

Zhang, Y., Wan, Y., Zhao, C.J., Shao, K Zhang, G., Li, H.T., Lin, H.D., Na, H., Novel side-chain-type sulfonated poly(arylene ether ketone) with pendant sulfoaUcyl groups for direct methanol fuel cells. Polymer, 2009, 50,4471-4478. 

Mcl-PHAs are also classified according to the type of substituent in the alkyl in the side chains so that poly(HAMCL)s containing unsubstituted n-alkyl groups are identified as medium-chain-length poly(3-hydroxy-n-alkanoate) [poly (nHAMCL)]. Both poly(nHAMCL) and PHAs containing unusual groups are described in Sect. 3. 

Copolymers of a-hydroxy acids and a-amino acids are one type of poly(ester-amide)s and are called polydepsipeptides (PDPs) [17]. Since some of natural occurring a-amino acids, typically Asp, Glu, lysine (Lys), cysteine (Cys), serine (Ser), and threonine (Thr), possess reactive (hydrophilic) side-chain groups, PDPs... 

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