Organocatalytic polymerization of ethylene carbonate

Abstract

Organocatalytic polymerization of ethylene carbonate (EC) with 3-phenyl-1-propanol (3PP) or triethylene glycol (TEG) as initiator and 1,5,7-triazabicyclo[4.4.0]dec-ene (TBD) as catalyst using a mono-mode microwave reactor results in poly(ether carbonate) s with Mn(GPC) values between 2200 and 3100g/mol and a ratio of ethylene oxide (EO) to ethylene carbonate (EC) repeating units of ca. 80/20 indifferent of the monomer to initiator ratio used. These poly(EO-co-EC) polymers are water soluble like PEO. However, in contrast to PEO they are amorphous and degradable by hydrolysis due to the randomly distributed carbonate groups. The lack of control of the degree of polymerization results from side reactions such as cyclization, transcarbonylation and fragmentation. The influence of different reaction parameters on these side reactions was determined by kinetic studies using size exclusion chromatography, 1H NMR and MALDI-ToF as analytical tools. Using TEG as initiator for this reaction hydroxyl telechelic poly(ether carbonate) s with an exact functionality of 2 were obtained. This allowed the preparation of a model polyester-block-poly(ether carbonate)-block-polyester triblock copolymer with low dispersity.