Copolymers side-chain groups

To design amphiphilic and/or reactive copolymers containing aliphatic polyesters, one of the most promising approaches is copolymerization with functional monomers having protected reactive side-chain groups. Some kinds of monomers having reactive (hydrophilic) side-chain groups have been reported (Fig. 3). Recently, the synthesis of various types of functional polyesters has been reviewed [15-19],... 

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... 

When MCA is copolymerized with MMA, the resulting copolymer etches faster than PMMA, consistent with the PMCA and MCN/MCA results. Incorporation of MCA, a monomer with a-chlorine, has the effect of decreasing plasma etch resistance, as is observed for the MCA homopolymer. Sensitization by chlorine appears to be general (see Tables I, III, and VI), except for the case where the chlorine is Incorporated onto the aromatic side chain group. This effect was observed previously by Taylor and Wolf for other polymer systems. ( ) The C-Cl bond strength is lower than that for C-H and C-F, and there is much evidence that this bond can be easily cleaved, even in the solid state. (, ) This weaker side chain group leads to lower dry-etch resistance. 

Other Py-GC and Py-GC/MS studies on polysiloxane copolymers are reported in literature [21, 22], etc. In one such study [21] several polysiloxanes used as liquid crystals, which contain benzyl ether and biphenyl ether side chain groups, were analyzed by Py-GC/MS. The general formula for these compounds is shown below ... 

Optical turbidity measurements showed a LCST for aqueous solutions of P14 up to 17°C. On the other hand, solutions of copolymer with cyclohexyl P15 have a transition at 31°C, which is 4°C lower than that of pure NIPAAM polymer P16 (Table 3). The lower LCST for P15 compared to P16 is attributed to the hydrophobic effect [60], which is the decrease of the LCST with increasing numbers of hydrophobic side-chain groups. 

A few reactions of side-chain groups have been investigated. Homopolymers or copolymers containing cyclohexenylethyl groups add hydrogen halides under electron-pain acceptor catalysis to give haloalkyl polymers... 

In addition to chiral side-chain group, chiral terminal group can also induce excess helicity in poly- and oligosilane chains. " Oligomer 222 and polymer 223 show CD absorptions based on an excess helicity. In addition, a single-handed helical poly(TrMA) segment induces single-handed helicity in polysilane chain in block copolymer 224. 

In addition to the radical attack of the end group, hydroxyl radical OH will attack the C-S and C-O-C bond in the copolymer side chain. Loss of a great number of sulfonate gronps or whole side chains would affect the proton conductivity of the membranes. Ghassemzadeh et al. studied chemical degradation of PFSA after fuel cell in sitn tests by solid-state NMR spectroscopy. The NMR spectra prove that degradation mostly takes place within the polymer side chains. ... 

The synthesis of cylindrical polymer brushes with amphiphilic poly(acrylic acid)-block-poly(n-butyl acrylate) (PAA-b-PnBA) diblock copolymer side chains is shown in Fig. 13.14. The procedure includes several steps (i) synthesis of a well-defined macroinitiator, PBIEM, by esterification of poly(2-hydroxyethyl methacrylate) (PHEMA), which was synthesized via ATRP of 2-hydroxyethyl methacrylate (HEMA) or anionic polymerization of silyl-protected HEMA (ii) ATRP of t-butyl acrylate (tB A) initiated by the pendant a-bromoester groups of PBIEM, yielding cylindrical brushes with PtBA homopolymer side chains (iii) sequential ATRP of n-butyl acrylate (nBA) forming the cylindrical bmshes with diblock copolymer [poly(t-butyl acrylate)-block-poly(n-butyl acrylate) (PtBA-b-PnBA)] side chains and (iv) hydrolysis of the PtBA block to produce the hydrophilic poly(acrylic acid) (PAA) block forming the core of an amphiphilic core-shell cylinder brash [106]. By using this technique, other well-defined core-shell cylindrical polymer brashes with polystyrene (PS), PS-b-PAA or PAA-b-PS, as side chains have been successfully synthesized. 

Properties have been determined for a series of block copolymers based on poly[3,3-bis(ethoxymethyl)oxetane] and poly [3,3-bis(methoxymethyl)oxetane]- (9-tetrahydrofuran. The block copolymers had properties suggestive of a thermoplastic elastomer (308). POX was a good main chain for a weU-developed smectic Hquid crystalline state when cyano- or fluorine-substituted biphenyls were used as mesogenic groups attached through a four-methylene spacer (309,310). Other side-chain Hquid crystalline polyoxetanes were observed with a spacer-separated azo moiety (311) and with laterally attached mesogenic groups (312). 

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