为获得性能优异的生物降解高分子材料，应用1，8-二氮杂二环[5。4。0]十一碳-7-烯(DBU)/碘化锂(Lil)双催化体系，以苯甲醇(BnOH)为引发剂，协同催化单体ε-己内酯(ε-CL)开环聚合，制备聚己内酯(PCL)，并利用高温凝胶色谱仪、超导核磁共振仪和差示扫描量热仪等仪器对所得产物进行表征和分析。结果表明:①以甲苯作为溶剂，ε-CL浓度为 2。0mol/L，n(ε-CL)∶n(DBU)∶n(LiI)∶n(BnOH)=100∶1∶1∶1，25 ℃时反应 40 min 得到的聚合物性能最优，此时PCL产率为98。5％，数均分子质量为22。8 kg/mol，分散性指数为1。15;②最优条件下制备的产物PCL的熔融温度为58。4 ℃，结晶温度为25。7 ℃;③1，8-二氮杂二环[5。4。0]十一碳-7-烯/碘化锂双催化体系催化ε-己内酯开环聚合机理为"单体-活化"机理。
Ring-opening polymerization of ε-caprolactone catalyzed by dual catalytic system of 1,8-diazabicyclo[5.4.0]undec-7-ene and lithium iodide
In order to obtain biodegradable polymer materials with excellent performance,polycaprolactone(PCL)was pre-pared by using the 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU)/lithium iodide(LiI)dual catalytic system,using benzyl alcohol(BnOH)as initiator and synergistically catalyzing the ring-opening polymerization of the monomer ε-caprolactone(ε-CL).The product was characterized and analyzed by high-temperature gel chromatography,superconducting nuclear magnetic resonance and differential scanning calorimeter.The results showed that:① The performance of PCL was optimal when toluene was used as solvent,the concentration of ε-CL was 2.0 mol/L,n(ε-CL)∶n(DBU)∶n(LiI)∶n(BnOH)=100∶1∶1∶1,T=25 ℃,t=40 min.The yield of PCL was 98.5％,the number average molecular weight of PCL was 22.8 kg/mol,and the polymer dispersity index of PCL was 1.15;② The melting temperature and crystallization temperature of PCL prepared under optimal conditions were 58.4 ℃ and 25.7 ℃,respectively;③ The mechanism of ring-opening polymerization of ε-caprolactone catalyzed by the 1,8-diazabicyclo[5.4.0]undec-7-ene/lithium iodide dual catalytic system was the"monomer activation"mechanism.
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