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Processes 2017, 5(2), 26; doi:10.3390/pr5020026

Comparison of Polymer Networks Synthesized by Conventional Free Radical and RAFT Copolymerization Processes in Supercritical Carbon Dioxide

1
Facultad de Química, Departamento de Ingeniería Química, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
2
Departamento de Física, Universidad Autónoma Metropolitana-Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Col. Vicentina, Ciudad de México 09340, Mexico
3
Facultad de Química, Departamento de Farmacia, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
4
Instituto Tecnológico de Tijuana, Centro de Graduados e Investigación en Química, A.P. 1166, Tijuana 22000, B.C., Mexico
*
Author to whom correspondence should be addressed.
Academic Editor: Alexander Penlidis
Received: 3 April 2017 / Revised: 27 April 2017 / Accepted: 4 May 2017 / Published: 9 May 2017
(This article belongs to the Special Issue Water Soluble Polymers)

Abstract

There is a debate in the literature on whether or not polymer networks synthesized by reversible deactivation radical polymerization (RDRP) processes, such as reversible addition-fragmentation radical transfer (RAFT) copolymerization of vinyl/divinyl monomers, are less heterogeneous than those synthesized by conventional free radical copolymerization (FRP). In this contribution, the syntheses by FRP and RAFT of hydrogels based on 2-hydroxyethylene methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) in supercritical carbon dioxide (scCO2), using Krytox 157 FSL as the dispersing agent, and the properties of the materials produced, are compared. The materials were characterized by differential scanning calorimetry (DSC), swelling index (SI), infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Studies on ciprofloxacin loading and release rate from hydrogels were also carried out. The combined results show that the hydrogels synthesized by FRP and RAFT are significantly different, with apparently less heterogeneity present in the materials synthesized by RAFT copolymerization. A ratio of experimental (Mcexp) to theoretical (Mctheo) molecular weight between crosslinks was established as a quantitative tool to assess the degree of heterogeneity of a polymer network. View Full-Text
Keywords: supercritical carbon dioxide; RAFT polymerization; hydrogels; polymer network homogeneity; solubility in supercritical fluids supercritical carbon dioxide; RAFT polymerization; hydrogels; polymer network homogeneity; solubility in supercritical fluids
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Pérez-Salinas, P.; Jaramillo-Soto, G.; Rosas-Aburto, A.; Vázquez-Torres, H.; Bernad-Bernad, M.J.; Licea-Claverie, Á.; Vivaldo-Lima, E. Comparison of Polymer Networks Synthesized by Conventional Free Radical and RAFT Copolymerization Processes in Supercritical Carbon Dioxide. Processes 2017, 5, 26.

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