由高效双键易位闭环反应合成环状聚ε-己内酯

SYNTHESIS OF CYCLIC POLY(ε-CAPROLACTONE) BY HIGH EFFICIENT RING-CLOSING METATHESIS REACTION

研究了合成环状大分子的一种新方法,即借助活性开环聚合反应和高效双键易位闭环反应(RCMR)合成环状聚ε-己内酯.首先,ε-己内酯在环状引发剂2,2-二丁基-2-锡-1,3-二氧环庚烷(DSDOP)的作用下,进行活性开环聚合反应,获得双羟基封端的聚ε-己内酯(PCLOH);然后,在对甲苯磺酸、1,3-二环己基碳二亚胺(DCC)和4-二甲氨基吡啶(DMAP)的作用下,将PCLOH与3-丁烯酸反应转化为双烯丙基封端的聚ε-己内酯(allylPCL);在Grubbs催化剂(Cl2(Cy3)2Ru CHPh)的作用下,将allylPCL经RCMR环化成环状聚ε-己内酯,并采用SEC,NMR,TGA以及DSC等技术对聚合物的结构和热力学性能进行了表征,SEC和黏度表征结果显示环状聚ε-己内酯具有较小的动态力学体积,TGA和DSC表征结果显示环状聚ε-己内酯的热分解温度较其线型前体高13℃,环化的结果使其熔点和结晶度下降.结果表明allylPCL在较稀(2.5×10-5mol/L)体系中,借助Grubbs催化剂进行的RCMR分子内环化反应效率高,环化产物无需进一步分离提纯.

A novel synthesis strategy combining of living ring-opening polymerization of ε-caprolactone and intramolecular cyclization by high efficient ring-closing metathesis reaction （RCMR） to synthesize cyclic macromolecules has been studied. First, homotelechelic PCL with hydroxyl end groups （PCLOH） was generated via living ring-opening polymerization of ε-caprolactone by using 2, 2-dibutyl-2-stanna-1, 3- dioxepane （DSDOP） as initiator. Second, homotelechelic PCLOH was reacted with vinylacetic acid, 1,3- dicyclohexylcarbodiimide （ DCC ） and 4-（dimethylamino） pyridine （DMAP） by utilizing p-toluenesulfonic acid monohydrate （PTSA） as catalyst and then converted to homotelechelic PCL with allyl end groups （allylPCL）. Finally,cyclic ploy（scaprolactone） was synthesized by ring-closing metathesis reaction of allylPCL by using bis （tricyclohexylphosphine） benzylidine ruthenium （IV） dichloride （ Cl2 （ Cy3 ） 2 Ru = C HPh） as catalyst under high dilution. The structures and thermodynamic properties of polymers were characterized by SEC, NMR,TGA and DSC technologies. The characterization by SEC and viscosity showed that the hydrodynamic volume of cyclic poly（ε-caprolactone） was smaller than that of its linear precursor. DSC study showed that the Tm and △Hm of cyclic poly （ε-caprolactone） was lower than those of its linear precursor. TGA test showed that the Tmax of cyclic poly（ε-caprolactone） was 13 K higher than that of its linear precursor. The results indicated that the intra-molecular cyclization of homotelechelic allylPCL by RCMR was high efficient under the high dilution （2.5 ×10^-5 mol/L） because the resulted cyclic PCL was pure and no need for further purification.