New Aspects on the Modeling of Dithiolactone-Mediated Radical Polymerization of Vinyl Monomers

Anete Benitez-Carreón,Alexander Penlidis,Ramiro Guerrero-Santos,Jesús Soriano-Moro,Eduardo Vivaldo-Lima

doi:10.3390/pr7110842

Abstract

A kinetic model for the dithiolactone-mediated radical polymerization of vinyl monomers based on the persistent radical effect and reversible addition (negligible fragmentation) was used to calculate the polymerization rate and describe molar mass development in the polymerization of methyl methacrylate at 60 °C, using 2,2-azobisisobutyronitrile (AIBN) as an initiator, as well as dihydro-5-phenyl-2(3H)-thiophenethione (DTL1) and dihydro-2(3H)-thiophenethione (DTL2) as controllers. The model was implemented in the PREDICI commercial software. A good agreement between experimental data and model predictions was obtained.

Highlights

Reversible deactivation radical polymerization (RDRP) techniques have become important in the last three decades [1].They provide versatile routes to synthesize polymers with tailored architectures [2]
Polymerization, propagating free radical molecule 1 adds to reversible addition–fragmentation chain-transfer (RAFT) agent 2, producing intermediate radical 3, which undergoes β-scision, yielding back the reactants or producing dormant polymer 4 and radical R· [6]
The main equilibrium reactions consist of the formation of intermediate radical 6 and its fragmentation into free radical 1 and dormant polymer 4

Summary

Introduction

Reversible deactivation radical polymerization (RDRP) techniques have become important in the last three decades [1]. They provide versatile routes to synthesize polymers with tailored architectures [2]. In RAFT polymerization, propagating free radical molecule 1 adds to RAFT agent 2 (see Figures 1 and 2), producing intermediate radical 3 (one-arm adduct), which undergoes β-scision, yielding back the reactants or producing dormant polymer (macro RAFT agent) 4 and radical R· [6]. In the “intermediate radical termination” (IRT) model [7], an additional reaction is considered, namely the cross-termination between free radical 1 and the intermediate radical 6, producing a star-shaped polymer (three-arm dead polymer), as seen in Figure 4 [6]. It is worth mentioning that further investigation has led to the Processes 2019, 7, 842; doi:10.3390/pr7110842 www.mdpi.com/journal/processes

Methods

Results

Conclusion