One Pot, One Feeding Step, Two-Stage Polymerization Synthesis and Characterization of (PTT-b-PTMO-b-PTT)n Multiblock Copolymers
文摘
We present here the one pot, one step synthesis of poly(trimethylene terephthalate)-block-poly(tetramethylene oxide) multiblock copolymers (PTT-b-PTMO-b-PTT)n by melt polymerization of cyclic oligo(trimethylene terephthalate)s (COTTs) with PTMO macroinitiator. An improved quantitative 1H NMR characterization technique was developed and applied to investigate the multiblock copolymers鈥?structure with different reaction time by the chain end and functional groups estimation. The polymerization kinetics was revealed, and the results indicated a two-stage polymerization mechanism: melt ring-opening polymerization of cyclic oligo(trimethylene terephthalate)s (COTTs) by PTMO macroinitiator to form triblock copolymers at first stage, followed by the in-situ condensation polymerization of block copolymers to produce multiblock copolymers at second stage. This was further confirmed by the gel permeation chromatography (GPC) and viscosity experiments. To our knowledge, this is the first reported poly(ether ester) multiblock copolymers synthesized by one step polymerization process and with controlled structures. These multiblock copolymers show good thermal stability and double crystalline properties.