Acrylic acid-based side-chain

Fig. 33 Illustration of the two extremes, homogeneous and segregated, of the distribution of hydrogen-bonded side chains along the backbone in the case of a substoichiometric composition. System PAA(LC) investigated consists of poly(acrylic acid) and side chains containing cyanobiphenyl mesogens connected with an alkyl chain to imidazole-based hydrogen-bond acceptors (Scheme 10c). Reprinted with permission from [242]. 2006 American Chemical Society...

A wide range of acrylates with various side chains have been polymerized using ATRP to obtain well-de ned functional polymers, e.g., ATRP of 2-hydroxyethyl acrylate, glycidyl acrylate, and tert-butyl acrylate (yielding well-de ned poly(acrylic acid) on hydrolysis). Among several transition metal catalysts, viz., copper, ruthenium, and iron-based systems, which have been successfully used for the controlled ATRP of acrylates, copper appears to be superior in producing well-de ned polyacrylates with low polydispersities. 

In 1950, Dahlquist et al. [82] reported the use of polyvinyl A -alkyl carbamates as PSA release materials. Since then, many other types of alkyl side chain polymers have been patented for use as release coatings, including copolymers based on higher alkyl acrylates or methaci ylates [83-86], polyvinyl esters of higher aliphatic fatty acids [87], higher alkyl vinyl esters or ethers and a maleic... 

A number of new resist materials which provide very high sensitivities have been developed in recent years [1-3]. In general, these systems owe their high sensitivity to the achievement of chemical amplification, a process which ensures that each photoevent is used in a multiplicative fashion to generate a cascade of successive reactions. Examples of such systems include the electron-beam induced [4] ringopening polymerization of oxacyclobutanes, the acid-catalyzed thermolysis of polymer side-chains [5-6] or the acid-catalyzed thermolytic fragmentation of polymer main-chains [7], Other important examples of the chemical amplification process are found in resist systems based on the free-radical photocrosslinking of acrylated polyols [8]. 

The hrst step in the preparation of the antidepressant maprotiline (33-5) takes advantage of the acidity of anthrone protons for incorporation of the side chain. Thus treatment of (30-1) with ethyl acrylate and a relatively mild base leads to the Michael adduct saponihcation of the ester group gives the corresponding acid (33-1). The ketone group is then reduced by means of zinc and ammonium hydroxide. Dehydration of the hrst-formed alcohol under acidic conditions leads to the formation of fully aromatic anthracene (33-2). Diels-Alder addition of ethylene under high pressure leads to the addition across the 9,10 positions and the formation of the central 2,2,2-bicyclooctyl moiety (33-3). The hnal steps involve the construction of the typical antidepressant side chain. The acid in (33-3) is thus converted to an acid chloride and that function reacted with methylamine to form the amide (33-4). Reduction to a secondary amine completes the synthesis of (33-5) [33]. 

A convenient procedure for preparing dialkylphosphinic acids 62 involves addition of H-phosphinic acids and esters to conjugated double bonds via the silyl 87-89 or metal phos-phonite 61,[90 94] as illustrated in Scheme 21. The silyl phosphonite intermediates 61 (M = TMS) are typically formed either from phosphinic acids or esters using chlorotri-methylsilane or bis(trimethylsilyl)acetamide. The metal phosphonite intermediates 61 (Y = Li, Na, etc.) are prepared by deprotonation of the acids with a base such as sodium hydride, sodium methoxide, or lithium diisopropylamide. The conjugated double bonds are typically acrylic acids and esters substituted in the a-position with the appropriate amino acid side chain. After appropriate protecting group manipulations, additional amino acids... 

Photolysis of this polymer gives radicals on which side chains can be formed, giving graft polymerization 122, 123, 153). Similarly the polymerization of styrene (152) or vinyl acetate (157) in the presence of bromotrichloromethane gives telomers carrying terminal bromine atoms and trichloromethyl groups. By ultraviolet irradiation (3500 A) in the presence of methyl methacrylate the carbon-bromine links are broken and block copolymers are formed. The telomerization of acrylonitrile and acrylic acid with bromoform is based on the same technique the end groups of both polyacrylonitrile and polyacrylic acid were photolyzed in the presence of acrylamide and afforded polyacrylamide blocks linked to polyacrylonitrile or polyacrylic acid blocks (164, 165). 

Water-based epoxy resins not applied by electrodeposition are mostly of the anodic type and maleinized epoxy esters are frequently used. Another class is the epoxy acrylic graft copolymer, where the epoxy resin is rendered water-soluble by attaching side chains of acrylic polymer containing a high amount of methacrylic acid. The process of grafting is similar to that of chain transfer (p. 67), where acrylic chains are attached by hydrogen abstraction. This process is illustrated in Fig. 14.2, where C- represents a radical site, and represents an extended acrylic chain containing both methacryclic acid and styrene components. 

Methacrylic monomers are relatively nontoxic, based upon oral, dermal, and inhalation exposure test data for rats and rabbits (30,34,35). However, these monomers can be skin sensitizers and are mildly to severely irritating after eye or skin contact. Liver and kidney damage can result from repeated near-lethal exposures. Overall toxicity is generally inversely proportional to the length of the side-chain ester group (see Acrylic and Methacrylic Acid Polymers). 

Acrylic polymers are based on esters of acrylic acid and methacryhc acid and copolymers are very common. Figure 13 shows the positive ion spectrum of poly(methyl methacrylate) (PMMA). Compared with the other oxygen-containing side-chain polymers discussed above, the spectrum appears to be influenced to a... 

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