Resist ester-protected chemical

One of the most important ester-protected polyhydroxystyrene-based resist copolymers, ESCAP (environmentally stable chemically amplified photoresist), developed at IBM, is based on the random copolymerization of 4-hydroxystyrene with tert-butyl acrylate (XXX).On exposure, this resist copolymer is converted to a copolymer of 4-hydroxystyrene with acrylic acid through photoinduced acid-catalyzed deprotection of the tert-butyl group (see Scheme 7.34). Because this resist system can be annealed at temperatures near its Tg in a process that hlls up the free volumes (voids in the resist matrix), thus preventing the out-diffusion of photoacids from the matrix and in-diffusion of airborne bases into the resist, neutralization reactions between the photoacids and bases in the resist matrix (otherwise known as poisoning) are reduced, thus allowing... 

Vinyl lacquers are used mainly where a high degree of chemical resistance is required these lacquers are based on vinyl chlorides and vinyl acetates. Acrylic lacquers are based on methyl methacrylate and methyl acrylate polymers and copolymers. Other esters of acrylic and methacrylic acid also may be used to make nonconvertible film formers. Judicious selection of these acrylic acid or methacrylic acid esters allows one to produce film formers with specifically designed properties such as hardness, flexibility, gloss, durability, heat, and chemical resistance. Acrylic lacquers, however, are not noted for their water resistance. The principal uses of acrylic-type lacquers are fluorescent and metallic paints, car refinish applications, clear lacquers and sealers for metals, and protective coatings for aircraft components and for vacuum-deposited metals, as well as uses in pigmented coatings for cabinets and appliances. 

Earlier research on phenolic substances in relation to plant disease resistance was concerned not only with the possible protective effects of preformed phenolic compounds, but also whether these compounds are mobilized or their synthesis is promoted at the site of infection. Another aspect which has received attention is that the phenolic compound might be liberated from its glycoside or sugar ester at the Infection site in response to Infection (5J. Chemical changes in Infected tissue due to the activity of polyphenol-oxidases and peroxidases, leading to the production of qulnones and other fungicidal compounds, have also been Investigated (6). 

Acetals and ketals have attracted a great deal of attention recently as protecting groups of PHOST due to their lower activation energies of deprotection than fBOC and terf-butyl esters. While the majority of chemical amplification resists require PEB to accelerate acid-catalyzed reactions, deprotection of ac-... 

A new type of copolymer resist named ESCAP (environmentally stable chemical amplification photoresist) has recently been reported from IBM [163], which is based on a random copolymer of 4-hydroxystyrene with tert-butyl acrylate (TBA) (Fig. 37), which is converted to a copolymer of the hydroxystyrene with acrylic acid through photochemically-induced acid-catalyzed deprotection. The copolymer can be readily synthesized by direct radical copolymerization of 4-hydroxystyrene with tert-butyl acrylate or alternatively by radical copolymerization of 4-acetoxystyrene with the acrylate followed by selective hydrolysis of the acetate group with ammonium hydroxide. The copolymerization behavior as a function of conversion has been simulated for the both systems based on experimentally determined monomer reactivity ratios (Table 1) [164]. In comparison with the above-mentioned partially protected PHOST systems, this copolymer does not undergo thermal deprotection up to 180 °C. Furthermore, as mentioned earlier, the conversion of the terf-butyl ester to carboxylic acid provides an extremely fast dissolution rate in the exposed regions and a large... 

Hendricks, A. L., de Kreij, A., and Moore, R. E. 1996. Vinyl ester Linings Protect FGD Systems, CORROSION 96, Paper No. 463, NACE International, Conferences Div., Houston, Texas. Hefiner, D. K. and Tuzla K. 1996. Plastic Membranes Protected with Chemical Resistant Masonry, CORROSION 96, Paper No. 402, NACE International, Conferences Div., Houston, Texas. 

Cellulose is the most abundant natural biopolymer and is readily available from renewable resources. Esterified cellulose is a highly flexible material as its properties can be varied by controlling the type and amount of the ester substituents during the chemical manufacturing process. Some cellulose esters have been applied as optical films for decades by virtue of their excellent properties such as high transparency and heat resistance. The cellulose ester used is mainly cellulose acetate, while the applications are rather limited to photographic films and protective films. 

---