Styrene-based resist, cross-linking

The cross-linking reaction mechanism is also influenced by the presence of other monomers. Methyl methacrylate is often used to improve the uv resistance of styrene-based resins. However, the disparate reaction rates of styrene and methacrylate monomer with the fumarate unsaturation not only preclude the use of more than 8% of the methacrylate monomer due to the significant slowing of the cross-linking reaction but also result in undercured products. 

Even resists based on poly(4-hydroxyl styrene) have been shown to be cross-linked in the DUV using 3,3-diazodiphenylsulfone and other bisazides as the... 

Different types of water-based emulsions are used in EPI adhesives. The most common are poly(vinyl acetate) (PVAc) emulsion, ethylene vinyl acetate (EVAc) emulsion, vinyl acetate-acrylate copolymerized (VAAC) emulsion, acrylic-styrene (AcSt) emulsion or styrene-butadiene rubber (SBR) latex or modified versions of these emulsion types [1, 8, 9], It has also been reported that tri- or ter-polymer emulsions like vinyl acetate-butyl acrylate-hydroxypropyl methacrylate or emulsions with different combinations of block copolymers can be used [4], Emulsion polymers containing cross-linking functional groups are especially well suited [4,6, 9]. The choice of emulsion(s) will, to a large extent, influence the adhesive properties such as setting time, bond quality, heat resistance, and moisture resistance. EPI adhesive systems are, however, very complex and the total composition (including the choice of cross-linker) and the interaction between the different components will determine the properties of the adhesive. Due to this it is difficult to describe in detail the effect of choosing one type of emulsion over the other. 

Styrene is the most widely used cross-linking monomer, being preferred because of its compatibility, low viscosity, ease of use and low price. Other materials are sometimes employed when special properties are required. For example, methyl methacrylate is used, often in conjunction with styrene, for the preparation of translucent sheeting. Diallyl phthalate (X) and triallyl cyanurate (XI) are used for heat resistant products. Partially polymerized diallyl phthalate (solid) is used as the cross-linking agent in moulding powders (the so-called alkyd polyester moulding powders) based on linear unsaturated polyesters. 

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