Ring-opening Polymerization of ω-Pentadecalactone Catalyzed by Organobases toward Degradable Polyethylene-like Plastics
This study reported that an efficient and controllable ring-opening polymerization of ω-pentadecalactone(PDL)by using cyclic trimeric phosphazene base(CTPB)as a catalyst and benzyl alcohol(BnOH)as an initiator.High molecular weight PPDL was obtained after optimizing the experimental conditions.The PPDL film with high molecular weight not only showed similar mechanical properties,crystallinity and high melting point(Tm=95.5 ℃)as polyethylene,but also exhibited the degradability of aliphatic polyesters.Differential scanning calorimetry(DSC)tests proved that PPDL had good crystallinity.Wide-angle X-ray scattering(WAXS)showed that PPDL had a unit cell structure similar to that of commercial high-density polyethylene(HDPE).Moreover,bishydroxyl-end-capped PPDL(PPDL-diol)can be easily prepared via ring opening polymerization(ROP)of PDL with 1,4-benzenedimethanol(BDM)as initiator.Then the PPDLs with high molecular weights were obtained by chain extension reactions with diisocyanates and showed enhanced mechanical properties.In addition,we synthesized a variety of random copolymers with different ratios of PDL to ε-caprolactone(ε-CL).The melting points and hydrolysis of the copolymers could be adjusted by changing the ratio of ε-CL.The melting points of the obtained random copolymers could be adjusted in the range of 53.0-95.5 ℃ by changing the ratio of ε-CL.Finally,the hydrolysis of PPDL copolyester was achieved under alkaline conditions.Compared with PPDL homopolymer,the hydrolysis of random copolymers showed faster hydrolysis rate and adjustability.
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