RUTHENIUM ALKYLIDENE INITIATED LIVING RING-OPENING METATHESIS POLYMERIZATION (ROMP) OF 3-SUBSTITUTED CYCLOBUTENES

The synthesis and living ring-opening metathesis polymerization (ROMP) of substituted cyclobutenes were investigated with the functional gro up tolerant initiators (PCy3)(2)Cl2Ru=CHCH=CPh2 (1) and (PCy3)(2)Cl2(R )u=CHPh (2). Synthetic methodology was developed for the synthesis of a wide variety of 3-functionalized cyclobutenes containing ether, este r, alcohol, amine, amide, and carboxylic acid substituents. Coordinati on of these functional groups to the propagating carbene was observed, resulting in the formation of a chelated propagating species with con comitant loss of one phosphine ligand from Studies aimed at understand ing this chelation and its effect on the polymerization On the basis o f these results, the synthesis of a series of functionalized cyclobute nes was accomplished which minimized this chelation and allow-ed for l iving polymerizations. A new class of functionalized poly(butadiene)s were synthesized and their thermal properties analyzed by thermogravim etric analysis and differential scanning calorimetry.