Abstract

This research was focused on the synthesis of core-shell bottlebrush polymer poly(PCL-b-PEG) (PCL: polycaprolactone; PEG: polyethylene glycol) through a combination of ring-opening polymerization (ROP) and ring-opening metathesis polymerization (ROMP). Three main steps were involved in this synthesis: firstly, the ROP of ε-caprolactone was conducted to form an amphiphilic linear polymer PEG-b-PCL in presence of methoxypolyethylene glycols and Sn(Oct)₂; secondly, macromonomers with norbornenyl-functionalization were synthesized by the esterification of the hydroxyl-terminated PEG-b-PCL with 5-norbornene-2-carboxylic acid; thirdly, the synthesized macromonomers were further polymerized by ROMP in presence of Grubbs second-generation catalyst to form a core-shell bottlebrush structured polymer. The effects of the reaction time, concentrations of small-molecule monomers, amount of catalyst and the molecular weights of macromonomers on the performance of the ROMP of the macromonomers were investigated in detail. ¹H NMR and GPC analyses confirmed the structures of the resulting polymers. DSC, XRD, TGA were used to characterize the properties of PEG-b-PCL and poly(PCL-b-PEG). Compared with the linear block polymers PEG-b-PCL, the resulting polymers with core-shell bottlebrush structures have a more regular chain arrangement and better thermal stability.

摘要

本研究的重点是通过开环聚合（ROP）和开环复分解聚合（ROMP）的组合合成核壳型瓶刷聚合物聚（PCL-b-PEG）（PCL：聚己内酯；PEG：聚乙二醇）。 ）。_{该合成涉及三个主要步骤：首先，在甲氧基聚乙二醇和Sn(Oct) 2}存在下，进行ε-己内酯的ROP以形成两亲性线性聚合物PEG-b-PCL。; 其次，通过羟基封端的PEG-b-PCL与5-降冰片烯-2-羧酸酯化合成降冰片烯基大分子单体；第三，合成的大分子单体在 Grubbs 第二代催化剂存在下通过 ROMP 进一步聚合，形成核壳式瓶刷结构聚合物。详细研究了反应时间、小分子单体浓度、催化剂用量和大分子单体分子量对大分子单体ROMP性能的影响。¹H NMR和GPC分析证实了所得聚合物的结构。采用DSC、XRD、TGA表征PEG-b-PCL和聚(PCL-b-PEG)的性质。与直链嵌段聚合物PEG-b-PCL相比，所得的核-壳瓶刷结构聚合物具有更规则的链排列和更好的热稳定性。