Premium
Stimuli‐ R esponsive Hydrogels Synthesis using Free Radical and RAFT Polymerization
Author(s) -
Gonçalves Miguel A. D.,
Pinto Virgínia D.,
Costa Rita A. S.,
Dias Rolando C. S.,
HernándesOrtiz Julio C.,
Costa Mário Rui P. F. N.
Publication year - 2013
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.201300045
Subject(s) - polymerization , suspension polymerization , radical polymerization , reversible addition−fragmentation chain transfer polymerization , monomer , self healing hydrogels , polymer chemistry , chain transfer , acrylic acid , materials science , precipitation polymerization , chemical engineering , chemistry , polymer , organic chemistry , engineering
Summary Temperature and pH stimuli‐responsive hydrogel particles were synthesized using inverse‐suspension polymerization in batch stirred reactor. Different water soluble co‐monomers were present in the initial mixture (e.g. N‐isopropylacrylamide and acrylic acid) as well as crosslinkers with different functionalities. Different operating conditions such as polymerization temperature, monomers dilution, neutralization and the initial ratios of co‐monomers and monomers/crosslinker were also tried. Hydrogel particles were produced considering classical free‐radical polymerization (FRP) and also RAFT polymerization. Commercially available RAFT agents 4‐cyano‐4‐phenylcarbonothioylthio‐pentanoic acid (CPA), 2‐(dodecylthiocarbonothioylthio)‐2‐methylpropionic acid (DDMAT) and cyanomethyl dodecyl trithiocarbonate (CDT) were alternatively used. Sampling at different polymerization times allowed the study of the kinetics of polymerization through the analysis by SEC of the soluble phase. A tetra‐detector array with simultaneous detection of refractive index, light scattering, intrinsic viscosity and ultra‐violet signals was used in these studies. Usefulness of in‐line FTIR‐ATR monitoring to study the building process of such networks was also assessed. The performance of hydrogel beads was studied through drug delivery tests triggered by changes in the environmental temperature and pH. This research aims to contribute for the elucidation of the connection between the synthesis conditions, molecular architecture and properties/performance of such advanced materials.