Synthesis of Poly(trimethylene carbonate) Oligomers by Ring-Opening Polymerization in Bulk

Telechelic poly(trimethylene carbonate) (PTMC) oligomers are synthesized and carefully characterized with molar masses between 300 and 5000 g mol(-1) in bulk by ring-opening polymerization (ROP) with 1,3-dioxan-2-one (trimethylene carbonate or TMC) as monomer and 1,4-butanediol (BDO) as co-initiator. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) organic catalyst and tin(II) bis(2-ethylhexanoate) (Sn(Oct)(2)) organometallic initiator are chosen comparatively. Due to the bi-functionality of BDO and relatively low TMC/BDO feed ratios, it is proved that PTMC chains are elaborated from one or both the BDO alcohol functions, producing two coexisting kinds of PTMC chains with BDO unit at the chain end or in the backbone. Additionally, PTMC chains bear permanent and fast exchange reactions at 100 degrees C, leading to both a dynamic redistribution of chains and their extension with BDO unit numbers mainly from 0-4 but up to 6. Longer reaction times and lower TMC/BDO molar ratios bring about more predominant exchange reactions and MALDI-TOF allows to detail the structures evolutions deeply. Better average molar masses control and narrower distributions are obtained with TBD as compared to Sn(Oct)(2). PTMC molar masses can be predicted simply by the TMC/BDO feed ratio with TBD. Kinetically, TBD is the most efficient. The glass transition temperature T-g is found to respect Flory-Fox model.