Preparation and properties of polymers of secondary alkyl crotonates and related monomers

The anionic polymerization of a variety of secondary alkyl crotonates and related monomers initiated by fluorenyllithium (complexed with tetrahydrofuran) in toluene at −78°C. is reported. No crystallinity could be developed in any of the samples, and nuclear magnetic resonance was uniformative about possible tacticity. The polymerization techniques were ineffective when applied to n ‐alkyl esters. Polymer was obtained from isopropyl cinnamate and N , N ‐dimethyl crotonamide, but not from isopropyl thiocrotonate or isopropyl 2‐pentenoate. The physical properties of injectionmolded specimens of polymers of isopropyl, s ‐butyl and cyclohexyl crotonate were examined in some detail; the polymers exhibited a desirable combination of high service temperatures and good impact resistance for a vinyl homopolymer but were extremely difficult to mold. Poly(isopropyl crotonate) had a heat distortion temperature of 125°C. at 85 psi, a notched Izod impact of 2.4 ft.‐lb./in. of notch, and a flexural modulus of 274,000 psi.