Alkali-developable base polymers

Alkali-Developable Base Polymers. Since the dissolution rate of PAAs is too fast in 2.38% TMAH solution, the photosensitive system composed of PAA and a DNQ compound suffers from low contrast of the difference in dissolution rate between exposed and unexposed area. It implies that the optimization of the dissolution rate of base polyimide precursor in the developer is needed. PAA/PAE blends, PAA/PAE copolymer, and PAE with pendant carboxylic acid (PAE-COOH) were evaluated as base polymers for photosensitive polyimides. 

We report on the positive alkali-developable photosensitive polyimides based on an alkali-soluble polyimide precursor as a base polymer and diazonaphthoquinone (DNQ) sensitizer to improve process stability and sensitivity. Polyamic acid ester with pendant carboxylic acid (PAE-COOH) showed good dissolution behavior in aqueous alkali developer. The dissolution rate of PAE-COOH was controlled by the content of pendant carboxylic acid. It was found that a photosensitive system composed of butyl ester of PAE-COOH and a DNQ compound can avoid the residue at the edge of hole patterns (footing) after development, while that of methyl ester of PAE-COOH showed the residue. A DNQ compound containing sulfonamide derived from diaminodiphenylether renders improved sensitivity compared with DNQ compounds derived from phenol derivatives. 

This chapter has shown the great efforts of researchers in Southeast Asia to develop cellulose-based polymer composite, especially from the abundant resources in Southeast Asia. In terms of mechanical properties, several treatments, from the cheapest alkali treatment to the expensive coupling agents, have been reported. However, developing a cellulose-based polymer composite that can compete with conventional fiber... 

Alkali-soluble emulsion polymers were originally developed as thickeners based on copolymers of acrylic acid and methacrylic acid with simple acrylic and methacrylic esters, as exemplified by their preparation in patents to S.C. Johnson... 

Poiyacids, based on anionicaiiy polymerized giyoxyiic esters were cleverly developed by Monsanto and the work published in a series of patents(49) and papers(50,51). The polymers are polyacetals, stable in alkali, but not in acid hence, in use as detergents, they are stable, but hydrolyze as the pH falls to 7 in the sewer systems, after use, to biodegradable monomer. 

In 1992, R.M. Laine (University of Michigan, Ann Arbor) announced the development of a process that transforms sand and other forms of silica into reactive silicates that can be used to synthesize unusual silicon-based chemicals, polymers, glasses, and ceramics. The Lame procedure produces pentacoordinate silicates directly from low-cost raw materials—silicon dioxide,ethylene glycol, and an alkali base. The mixture is approximately a 60 1 ratio of silica gel, fused silica (or sand) to metal hydroxide and ethylene... 

A procedure based on condensation with phenol and paraform (used as formaldehyde source) was developed to convert spent UNEX solvent (CCD, PEG-400, Ph2-CMPO, and FS-13) into a solid infusible resin for disposal. The resulting material is insoluble in aqueous alkali and acidic solutions and organic solvents. Incorporation of FS-13 in the cross-linked polymer was confirmed by physicochemical methods. Resistance of the cured resin to high temperatures was proven by thermogravimetry... 

Positive Photoresists. Positive resists are entirely different from negative resists. For the purposes of this discussion we restrict ourselves to visible-light-sensitive materials. Typically, these materials are mixtures of low-molecular-weight phenol-formaldehyde polymers and derivatives of naphtho-1,2-quinone diazide, the photosensitive component. The former is soluble in aqueous alkali, but the presence of the latter, a hydrophobic species, inhibits attack of this developer on the film. On irradiation the "sensitizer" is converted to a ketene, which, after reaction with water, forms a base-soluble carboxylic acid. Thus the irradiated part of the film is rendered soluble in the developer and it can be removed selectively. The important feature of this system is that the unirradiated areas are not swollen by the developer and the resolution of this material is quite high. It is possible to prepare gratings having several... 

The design of superior polymer catalysts is alw -s related to substrate selectivity and efficient turnover of catalysts. Some selectivity was observed among substrates that was due to hydrophobic and electrostatic factors. Especially the cooperative action of these two factors was effective for rate enhanconents. The efficiency of acid and alkali hydrolyses was increased iq> to 100 times in the presence of prdymers, but the simple polyelectrolyte effect would not yield further rate enhaiK menL More elaborate systems that include efficient general add and base catalyses must be developed. 

Ion Optodes The principles underlying the sophisticated complex polymer-based matrices for ISEs are the same as those used to design and construct ion-selective optical sensors, the optodes. Ion optodes have been developed for H, alkali metal ions, NH, Ca, NO, and CO . Numerous sensors for... 

Advanced crack-resistant coatings based on water dispersion of chlorine-sulpho-polyethylene (CSPE, Hypalon ) vulcanized by a Mannich alkali (MA) water solution were obtained. Application of MA as a CSPE structure component makes it possible to produce a vulcanized net of saturated polymer, and thus to develop an ecologically safe, impenetrable crack-resistant coating for any substrata (concrete, metal, plastic, etc.). The coatings can be applied in the aircraft, automotive, shipbuilding, paint, and varnish industries, civil engineering, and so on as a corrosion-resistant material. The optimal coating composition and its mechanical properties have been studied. 

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