Study on MMA and BA Emulsion Copolymerization Using 2,4-Diphenyl-4-methyl-1-pentene as the Irreversible Addition-Fragmentation Chain Transfer Agent.

Zuxin Zhang,Daihui Zhang,Riqing Chen,Gaowei Fu,Fuxiang Chu,Chunpeng Wang

doi:10.3390/polym12010080

Abstract

As a chain transfer agent, 2,4-diphenyl-4-methyl-1-pentene (αMSD) was first introduced in the emulsion binary copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA) based on an irreversible addition–fragmentation chain transfer (AFCT) mechanism. The effects of αMSD on molecular weight and its distribution, the degree of polymerization, polymerization rate, monomer conversion, particle size, and tensile properties of the formed latexes were systematically investigated. Its potential chain transfer mechanism was also explored according to the 1H NMR analysis. The results showed that the increase in the content of αMSD could lead to a decline in molecular weight, its distribution, and the degree of polymerization. The mass percentage of MMA in the synthesized polymers was also improved as the amounts of αMSD increased. The chain transfer coefficients of αMSD for MMA and BA were 0.62 and 0.47, respectively. The regulation mechanism of αMSD in the emulsion polymerization of acrylates was found to be consistent with Yasummasa’s theory. Additionally, monomer conversion decreased greatly to 47.3% when the concentration of αMSD was higher than 1 wt% due to the extremely low polymerization rate. Moreover, the polymerization rate was also decreased probably due to the desorption and lower reactivity of the regenerative radicals from αMSD. Finally, the tensile properties of the resulting polyacrylate films were significantly affected due to the presence of αMSD.

Highlights

Due to the growing environmental concerns, emulsion polymerization has become a vital method for polymer production with its environmentally friendly process, high polymerization rate, high monomer conversion, and excellent heat dissipation performance [1]
As the addition of αMSD increased from 0% to 0.1%, the number-average molecular weights were decreased from 40.56 × 104 to 28.58 × 104 g/mol, whereas monomer conversion underwent a slight decrease to 97.8%
When αMSD concentration increased from 0.1% to 1%, both molecular weights and monomer conversion were significantly decreased, as the presence of αMSD was able to effectively interfere with the polymerization process

Summary

Introduction

Due to the growing environmental concerns, emulsion polymerization has become a vital method for polymer production with its environmentally friendly process, high polymerization rate, high monomer conversion, and excellent heat dissipation performance [1]. Chain transfer agent (CTA) as an important component, including reversible addition–fragmentation chain transfer (RAFT) and traditional CTAs, have been widely employed to control the molecular weights of synthesized polymers during the emulsion polymerization. Many works about RAFT CTAs have recently been conducted, the complex processes and strict operation conditions of RAFT CTAs limit their wide applications. [4,5,6] For traditional CTAs, including mercaptans [7,8,9,10], alcohols [11], and halides [12], Polymers 2020, 12, 80; doi:10.3390/polym12010080 www.mdpi.com/journal/polymers. In the the case case of for alcohols, the amount amount used several disadvantages have been observed, such an unpleasant smell mercaptans and serious mercaptans and environmental pollution for halides. Many works about RAFT CTAs have recently been conducted, the complex processes and strict operation conditions of RAFT CTAs limit their wide applications. [4,5,6] For traditional CTAs, including mercaptans [7,8,9,10], alcohols [11], and halides [12], Polymers 2020, 12, 80; doi:10.3390/polym12010080 www.mdpi.com/journal/polymers

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Conclusion