John A. Simms

Recent advances in the use of star polymers in coatings

Abstract The synthesis of methacrylate stars by an arm-first process using ethylene glycol dimethacrylate as the core-forming material is described. The level of free arm is an indicator for the extent of termination during the preparation. Using 0.2% (mole basis) of catalyst on initiator instead of higher concentration is helpful. Modifiers for the anion catalyst used in group transfer polymerization (GTP) can be used to reduce termination. Clarity of the two-phase blends with polyester polyol and isocyanate crosslinking agent depended on star composition, hydroxyl-number (OH#) and star level. Recently, benzyl methacrylate has been introduced into this technology to give improved film hardness and clarity with cycloaliphatic polyester coreactants. This permits use of 25–30% star to give fast dry and improved hardness/flexibility balance while also allowing the application at less than 3.5 Ib/gallon of solvent.

The Preparation and Photooxidative Degradation of Polyesterurethanepoly(Methyl Methacrylate) Triblock Copolymers

Block copolymers of the ABA type made from hydrocarbon monomers by anionic polymerization have been extensively investigated (1, 2). Much less has been done with nonhydrocarbon block polymers. Such systems as have been repotted show even broader temperature ranges of technical utility than the more familiar styrene/diene/styrene systems (3, 4, 5). It is the purpose of this paper to describe a process for preparing polymethyl methacrylate containing triblock copolymers. The physical property balances that can be gotten and the photooxidative degradation processes that occur will also be covered.