Autoacceleration and Cyclization Effects on Styrene/Divinylbenzene Copolymerization

Abstract

Copolymerizations of styrene with divinylbenzene (DVB) are carried out at low monomer concentrations in order to evaluate the incidence of cyclization reactions. The pendant double bond concentration in the synthesized polymers is measured using Fourier transform infrared spectroscopy. Reactions are carried out at monomer concentrations of 6% and 2% (v/v), DVB concentration in the range 15–80 wt% and temperatures in the range 60–90 °C. A previously developed model is used to interpret the results and analyze the cyclization effects. The predictions of the model accounting for cyclization reactions present a better agreement to the experimental data in comparison to predictions without cyclizations. Autoacceleration effects are observed for cases with higher DVB concentrations, in which the formation of highly entangled structures may have occurred. The model provides an estimate of 0.05 for the crosslink parameter (CP) and 130 s−1 for the rate constant of cyclization for the smallest sequence (three units) at 90 °C.

Modelling Development in Radical (Co)Polymerization of Multivinyl Monomers

“…Besides, due to the extensive cyclization, the average reactivity of PDB for intermolecular crosslinking was 2–3 orders of magnitude lower than that of the free vinyls. Following Okay's methodology, the effects of solvent on the cyclization kinetics in FRcP of styrene and DVB were modeled by Aguiar et al [49, 50] . using the NF technique.…”

“…Besides, due to the extensive cyclization, the average reactivity of PDB for intermolecular crosslinking was 2-3 orders of magnitude lower than that of the free vinyls. Following Okay's methodology, the effects of solvent on the cyclization kinetics in FRcP of styrene and DVB were modeled by Aguiar et al [49,50] using the NF technique. They reported that the cyclization is more favored in reaction systems containing a poor solvent than a good solvent, suggesting the more the chain is stretched out, the lower the intrinsic rate of cyclization.…”

Prediction and comparison of textural properties of magnetic copolymer supports for enzyme immobilization

“…For instance, Hamzehlou et al studied the nitroxide‐mediated radical copolymerization of styrene (STY) with DVB and used Monte Carlo simulations to quantify the homogeneity of polymer networks. Santos et al modeled the conventional STY/DVB copolymerization and detected autoacceleration and cyclization by fitting model parameters. Although powerful tools, these models cannot predict the textural properties of resins.…”

Estudo da formação de redes poliméricas através da técnica de polimerização em miniemulsão: estudo experimental e modelagem matemática.

“…Uma quantidade considerável de trabalhos abordou esse tema e se dedicou a determinar o valor desse parâmetro em sistemas homogêneos (Aguiar, 2013;Aguiar, et al, 2014;Santos, et al, 2017).…”

“…Apesar de amplamente estudadas, ainda existem divergências quanto à cinética do parâmetro responsável pelas ligações cruzadas (Gonçalves et al, 2013;Aguiar, 2013;Santos et al, 2017).…”