Tert-Butyl Alpha-(Hydroxymethyl Acrylate and Its Ether Dimer: Multifunctional Monomers Giving Polymers With Easily Cleaved Ester Groups

Two new members of the readily available family of alpha-functionalized acrylates have been synthesized, characterized, and polymerized. Reaction of tert-butyl acrylate with paraformaldehyde in the presence of catalytic 1,4-diazabicyclo[2.2.2]octane and tert-butyl alcohol at elevated temperatures leads to ca. 25% yields of tert-butyl alpha-(hydroxymethyl)acrylate. Continued reaction leads to ca. 80% conversion to the dimer ether of this material. Radical polymerization of the hydroxymethyl monomer occurs readily to give polymer of ca. 4.5 x 10(5) molecular weight and intrinsic viscosity of 0.6 dL/g. Solution C-13 NMR peak multiplicities appear consistent with atactic polymer rich in syndiotactic units. Copolymerization with styrene occurs readily to give products that appear to be essentially random copolymers based on their physical and spectral properties. Cyclopolymerization of the ether dimer occurs spontaneously in bulk at \u3e 120-degrees-C or with azobisisobutyronitrile (AIBN) in solution to give soluble polymer with an intrinsic viscosity in CHCl3 of 0.8 dL/g and a molecular weight of 7.5 x 10(5). Thermolysis of the hydroxymethyl polymer removes the tert-butyl group but generates lactone and ester groups as indicated by FTIR and especially solid-state C-13 NMR data. Mild, quantitative cleavage of the tert-butyl ester moieties of both the hydroxymethyl polymer and the cyclopolymer was achieved with neat trifluoroacetic acid. The obtained free-acid polymers exhibit polyelectrolyte behavior during viscosity measurements in dilute base but give normal straight-line plots in 1 N aqueous salt