Synthesis of high glass transition temperature (meth)acrylic polymers bearing norbornadiene dimer via Lewis pair polymerization

The introduction of bulky and rigid polycyclic hydrocarbons into the polymer side chains enhanced the glass transition temperature (Tg), broadening the application range of the polymer. We synthesized and polymerized new acrylate and methacrylate monomers bearing a norbornadiene dimer, exo-exo-4-pentacyclo[8.2.1.15,8.02,9.03,7]tetradecanyl acrylate (1) and methacrylate (2). The polymerizations of 1 and 2 using Lewis pair catalysts comprising B(C6F5)3/PPh3 and methylaluminum bis(2,6-di-tert-butyl-4-methylphenoxide) (MAD)/PCy3, respectively, proceeded with full conversions. The Tg of the poly1 and poly2 were approximately 120 °C and 200 °C, respectively. Considering the Tg and tacticity of poly2 obtained via radical polymerization (Tg = 135 °C; syndiotactic triad (rr) = 63%), the high Tg value can be reasonably assumed to be due to the high syndiotacticity (Tg = 206 °C; rr = 87%) caused by the steric repulsion between the propagating terminal MAD and the penultimate norbornadiene dimer moiety.