Poly a-substituted

Positive Electron-beam Resist of Poly (a-substituted Benzyl Methacrylate). The electron-beam resist behaviors of poly(a-substituted benzyl methacrylate)s are given in Table III. When the exposed resist films were developed with a mixture of MIBK and IPA, the sensitivities of these polymers were on the order of 10-4 C/cm2. When a dilute solution of sodium methoxide in methanol was used as a developer, the sensitivity was enhanced as compared with the former case, and increased with an increase in the bulkiness of the ester group of the polymer except for poly(a,a-diphenylethyl methacrylate). 

Then the decomposition is expected to be more favorable as the number of / -hydrogen atoms is larger. This is the case for the poly(a-substituted benzyl methacrylate)s as shown in Figure 7. However, when poly(t-butyl methacrylate) containing nine / -hydrogen atoms was exposed to an electron-beam, the amount of acid group formed was smaller than that for poly (a,a-... 

Poly(styrenes) and poly(a-substituted styrenes) can bear various substituents on the aromatic ring. These substituents may affect other properties of the polymer, but their thermal stability is not very different from that of unsubstituted poly(styrene). Some of the idealized structures of the polymers in this group are shown below ... 

Besides the most typical PNIPAAm in the family of poly(A-substituted acrylamide), there are many other polymers (Fig. 9.4) that show varied transition properties in response to temperature changes. For example, poly(A, Af -diethyl acrylamide) (PDEAAm) has an LCST in the range of 25-32 °C [4], poly[A-(D,L)-(l-hydroxymethyl) propylmethacrylamide] (PDL-HMPMA) has one close to 35 °C... 

Alkyl-substituted pyrroles are not easy to synthesize and relatively few reports on poly (3-alky Ipyrrolejs have been published [213-216]. These polymers are much more conductive than the corresponding poly(A -substituted-pyrrole)s and, under some selected experimental conditions (propylene carbonate as solvent and PF,- as counterions), even more conductive (270 S cm ) than PP itself [215]. 

Figure 7.10 Poly (A -substituted acrylamide) showing a LCST (a) Poly (iV-isopro-pylaciylamide) (PNIPAAm) (b) Poly(AyV-diethylacrylamide) (PDEAAm) (c) Poly(2-carboxyisopropylacrylamide) (PCIPAAm) (d) Poly(A -(Z) (l-hydroxymethyl), pro-pylmethacrylamide (P(Z-HMPMAAm)) (e) Poly(A - acryloyl-A/ -alkylpiperazine) [124]...

Occasionally, water-soluble plastics are required. Poly(vinyl alcohol) is commonly the first to be considered but some cellulose ethers, polyethylene oxides, poly(vinyl pyrrolidone) and A-substituted polyamides are among many possible alternatives. 

Macromolecular Substitution Route. The current surge in poly-phosphazene research Is mainly a result of the development in the mid 1960 s (2-4) of a substitutive route to the synthesis of organo phosphazene high polymers. Before that time, only a sporadic interest in the subject existed because the known polymers, cross linked poly(dihalophosphazenes), (1,5) were insoluble and hydrolytically unstable. 

Poly(iV-substituted dithieno[3,2-3 2, 3 -rf pyrroles (PDTPs) 167a,b) <2005MM4545>, a class of soluble (chiral) conjugated polymers with a stable oxidized state, were prepared by an oxidative coupling by FeClj in chloroform under an argon atmosphere. The crude material was reduced with hydrazine to afford compound 167 (Scheme 19) <2005MM4545>. 

Tachibana Y, Kurisawa M, Uyama H et al (2003) Thermo- and pH-responsive biodegradable poly(a-A-substituted y-glutamine)s. Biomacromolecules 4 1132-1134... 

Sulfonated poly(4-substituted benzoyl-1,4-phenylene) homopolymers and copolymers using concentrated sulfuric acid or fuming sulfuric acid have been shown to form sulfonated polymers with variable degrees of sulfonation. To improve film formation of the sulfonated polyphenylenes, multiblock copolymers have been synthesized by reacting a more flexible poly(arylene ether sulfone) with sulfonated poly-phenylenes. ... 

Figure 34. The Polystyrenes. Polystyrene is a low sensitivity negative resist, poly (a-methylstyrene) is a low sensitivity positive resist and the para-substituted analogs listed are all sensitive negative resists.

Ridd and Yoshida explored the At-nitration of aromatic nitroanilines with nitronium hex-afluorophosphate in nitromethane with the aim of studying the Bamberger rearrangement (Chapter 4, Section 4.5). In was found that amines of low basicity essentially undergo complete A -substitution if the amine is in excess 2,4-dinitroaniline and 2,3-dinitroaniline form A, 2,4-trinitroaniline and At,2,3-trinitroaniline, respectively, as the sole products. More basic nitroanilines give mixtures of C-substituted, At-substituted and poly-substimted materials. The use of nitronium salts for At-nitration has been extensively reviewed. ... 

Stereosequences in polymers having the general formula — CHR—X—Y— [e.g., poly-a-amino acids, polymers derived from substituted oxiranes, thi-iranes, aziridines, lactones or lactams, and 1,4 polymers of 1- (or 4) monosub-stituted butadienes] are not affected by the degeneracy phenomena existing in vinyl polymers. Their number is indicated in the first column of Table 2. 

Various endo-imino cyclic ethers (L) undergo cationic polymerization to yield poly(A-acylalkyleneimine)s (LI). The most widely studied monomers are the 2-substituted 2-oxazo-lines (m = 2) (also referred to as 2-substituted-l,3-oxazolin-2-enes) [Culbertson, 2002 ... 

Thus, the PEO segment actually becomes hydrophobic at higher temperatures. This temperature-dependent change converts the amphiphilic block copolymer to a water-insoluble hydrophobic polymer (Topp et al. 1997 Chung et al. 2000). The temperature at which the polymer exhibits this transition is called its lower critical solution temperature (LCST). In addition to PEO, substituted poly(A -isopropyl acrylamide) (PNIPAM Chart 2.1) exhibits temperature sensitivity, where the LCST can be tuned by varying the alkyl fimctionahty. The guest encapsulation combined with the temperature-sensitive precipitation of the polymers has been exploited to sequester and separate guest molecules from aqueous solutions (Fig. 2.4). 

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