Abstract:

To obtain well-defined structures of α-cyclodextrin (α-CD) based monomer and its hyperbranehed polymer (HBP), a modified α-CD molecule with one electron-rich alkene and many electron-poor acrylates was first prepared through the esterification reaction between mono-ester undecylenic acid-α-CD and acrylic acid. It was then utilized as an AB_n-type monomer for subsequent ADMET polymerization between alkene and acrylate using the second generation Hoveyda-Grubbs catalyst in homogeneous water/organic [D₂O/(CD₃)₂CO] mixtures via acyclic diene metathesis (ADMET) polymerization. A novel cyclodextrin-based HBP was obtained in prolonged reaction time. The monomer and HBP were characterized by NMR, elemental analysis, FTIR, and MALDI-TOF MS measurements. It was found that the actual molecular structures of both monomer and polymer were identical with the designed structures. The produced polymers have molecular weights within 13.2 and 56.3 kDa, and their polydispersity indices range from 2.78 to 2.63 by multiangle laser light scattering-gel permeation chromatography. The degree of branching was determined by ¹H NMR spectroscopy and the values ranges from 0.41 to 0.52.

摘要：

为了得到结构确定的α-环糊精（α-CD）单体并用于聚合，通过对由单取代十一烯酸酯化的α-CD上羟基的酯化，得到AB_n型功能化α-CD类单体，并利用Hoveyda-Grubbs第二代催化剂引发该单体在水/有机溶剂[D₂O/(CD₃)₂CO]中的非环二烯烃易位聚合，一步法得到新型超支化聚（α-CD）。采用¹H NMR、FTIR、飞行时间质谱（MALDI-TOF MS）和元素分析对AB_n型α-CD单体及其超支化聚合物的结构进行表征。结果表明，单体和聚合物的结构与所设计的分子结构相符合。多角度激光光散射/凝胶渗透色谱（MALLS–GPC）联用仪测得超支化聚（α-CD）的数均分子量为13200～56300，分子量分布在2.78～2.63。利用¹H NMR图谱计算出该聚合物支化度在0.41～0.52。