Ring Opening Metathesis Polymerization(ROMP) ofcis- andtrans-3,4-Bis(acetyloxymethyl)cyclobut-1-enes and Synthesis of Block Copolymers

Abstract : The synthesis and living ring opening metathesis polymerization (ROMP) of diacetate functionalized cyclobutene derivatives cis-3,4-bis(acetyloxymethyl)cyclobutene (2) and trans-3,4-bis(acetyloxymethyl)cyclobutene (3) were investigated with the functional group tolerant initiators (PCy3)2(Cl)2RuCHPh (I) and (SIMes)(PCy3)(Cl)2RuCHPh (II) (SIMes: 1,3-dimesityl-4,5-dihydroimidazol-2-ylidene). The kinetic parameters of the ROMP initiated by the ruthenium alkylidene complexes I and II were determined and correlated to monomer stereochemistry. The cis isomer 2 was found to be more reactive than the trans isomer 3 and to generate functional polymers of narrow molecular weight distribution especially with the classical “first generation Grubbs catalyst” I. Block copolymers containing 2 and cyclooctadiene (COD) or norbornene (NBE) were synthesized. Block copolymer poly(2-b-COD) was hydrolyzed and converted to a material with a block bearing hydrophilic alcohol functional groups and hydrophobic block.