新型功能性环状聚(ε-己内酯-co-α-氯代-ε-己内酯)的合成

SYNTHESIS OF NEW FUNCTIONAL CYCLIC POLY( ε-CL-co-α-Cl-ε-CL)

借助活性开环聚合反应和紫外光辐照下的分子内交联反应合成新型功能性环状聚(ε-己内酯-co-α-氯代-ε-己内酯)(cP(εCLcoαClεCL)).首先,利用Baeyer-Villiger氧化法将α-氯代环己酮在间氯过氧苯甲酸(mCPBA)的作用下制得功能性单体α-氯代-ε-己内酯(αClεCL).然后,功能性单体αClεCL和ε-己内酯(εCL)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活性环状无规共聚酯(LCP(εCLcoαClεCL))前体,该前体的分子量可以通过改变单体与引发剂的摩尔配比来控制.当单体完全转化后,该活性环状前体再引发反应性单体α-(1-丙烯酰氧乙基)-ε-己内酯(αAEεCL)进行嵌段聚合反应,合成了在活性中心附近带有不饱和双键的功能性环状共聚酯,即活性环状聚(ε-己内酯-co-α-氯代-ε-己内酯)-b-(α-(1-丙烯酰氧乙基)-ε-己内酯).最后该活性环状共聚酯在紫外光辐照下,反应性单体单元中的双键发生分子内交联反应,制得稳定的不含有机锡的新型功能性环状无规共聚酯cP-(εCLcoαClεCL)(M n,NMR=32400).采用SEC,NMR以及DSC等技术对聚合物的结构和性能进行表征,SEC和黏度表征结果显示新型功能性cP(εCLcoαClεCL)与分子量相同的线型共聚酯相比具有较小的动态力学体积,DSC表征结果显示共聚酯环化的结果使其熔点和结晶度下降.该方法的突出特点是能够高效地合成具有高分子量的环状聚合物.

This work aims at developing a strategy to synthesize functional cyclic copolyesters,based on the living ring-opening polymerization and the intra-molecular cross-linking reaction by UV irradiation.First,α-chlorocyclohexanone was converted into α-chloro-ε-caprolactone （αClεCL） in the presence of m-chloroperoxybenzoic acid （mCPBA） by the Baeyer-Villiger oxidation.Second,the quantitative polymerization of a mixture of εCL and the functional monomer αClεCL was initiated in toluene by 2,2-dibutyl-2-stanna-1,3-dioxepane （DSDOP） to obtain a precursor,i.e.,a living cyclic copolyesters （LCP（εCLcoαClεCL））.The molecular weight of the precursor can be controlled by varying the molar ratio of monomer to initiator.When the comonomers were converted completely,a fresh feed of α-（1-acryloyloxyethyl）-ε-caprolactone （αAEεCL） was added to the polymerization medium to achieve living cyclic copolyesters,poly（（εCLcoαClεCL）-b-（αAEεCL））.Finally,the functional cyclic copolyester which is stable and free of tin dialkoxides,i.e.,cP（εCLcoαClεCL） （Mn,NMR=32400）,was synthesized by the intramolecular photo cross-linking of few acrylic unsaturations in the close vicinity of the living cyclic chain under UV irradiation.The structures and properties of the polymers were characterized by SEC,NMR and DSC technologies.The characterization by SEC and viscosity showed that the hydrodynamic volumes of the functional cyclic copolyesters were smaller than those of their linear counterparts.DSC study showed that both the melting point and degree of crystallinity of the functional random copolyesters decreased upon cyclization.The strategy herein proposed has been successfully tested for the synthesis of cyclic copolyesters with high molecular weight and high efficiency.