Revisiting the structure of copolymer via anionic hybrid copolymerization of methyl methacrylate and e-caprolactone

作者：Yang, Hongjun; Yao, Hongxin; Feng, Kaifeng; Zhang, Guangzhao^*

来源：Polymer, 2022, 260: 125340.

DOI：10.1016/j.polymer.2022.125340

• Hybrid copolymerization
• Sequence
• Transesterification

Anionic hybrid copolymerization of vinyl and cyclic monomers provides a powerful strategy to synthesize het-eropolymers. Yet, there are some open questions regarding its mechanism and the structure of the resulted polymer. We reported that the copolymer (Poly(MMA-co-CL)) of methyl methacrylate (MMA) and e-caprolactone (CL) via such copolymerization was random. However, a recent study proposed that the copolymer might be simple graft one with poly(methyl methacrylate) (PMMA) as the main chain and poly(e-caprolactone) (PCL) as the graft chain. In this study, we synthesized a model graft copolymer (PMMA-g-PCL) by using a combination of reversible complexation-mediated polymerization and ring-opening polymerization, and made comparison with Poly(MMA-co-CL) in their properties and hydrolysis. Differential scanning calorimeter (DSC) measurements show that the graft copolymer PMMA-g-PCL possesses two glass transitions and a melt peak. In contrast, Poly(MMA-co- CL) exhibits only one glass transition without a melt peak because it is amorphous, clearly indicating that it is random. Proton nuclear magnetic resonance (1H NMR) measurements reveal that the hydrolysis of PMMA-g-PCL yields only PMMA oligomers. However, the hydrolyzed products of Poly(MMA-co-CL) consist of MMA and CL units. The facts further indicate that the copolymer Poly(MMA-co-CL) is random. Considering that the trans-esterification reactions are unavoidable in the anionic hybrid copolymerization, the copolymer should consist of random main chain and random branches.

• 单位
  常州大学