A New Thermo-Sensitive Hydrogel: Poly(ethylene oxide-dimethyl siloxane-ethylene oxide)/Poly(N-isopropyl acrylamide) Interpenetrating Polymer Networks I. Synthesis and Characterization

Abstract

ABSTRACT:Interpenetrating polymer networks (IPNs) composed of poly(ethylene oxidedimethyl siloxane-ethylene oxide) (PEO-PDMS-PEO) ABA triblock copolymer and poly(Nisopropyl acrylamide) (PIPAAm) were synthesized. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) studies of bulk IPNs revealed micro phase separation with partial phase mixing between two chemically independent networks. Aqueous equilibrium swelling curves were examined as a function of temperature. DSC thermograms of the swollen IPNs exhibited the same swelling transition temperature as that of PIPAAm, although the degree of swelling of IPNs was affected by polymer composition. These observations indicate that each network in the swollen IPNs exists independently and many have different morphology than the dried bulk state. The aqueous swelling-deswelling kinetics by temperature modulation of IPNs could be controlled by gel composition nd temperatures applied.KEY Crosslinked poIy( N -isopropyI aerylamide) (PIPAAm) demonstrates a sharp swelling transition (gel shrinking) around its LCST of 31-which may be unique among thermosensitive gels due to a relatively symmetric and sharp endothermic peak at the swelling transition temperature in DSC studies."Recently, crosslinked PIPAAm and its copolymer with a hydrophilic (HPL) componentPolym.

Preparation and swelling behaviors of rapid responsive semi-IPN NaCMC/PNIPAm hydrogels

“…Therefore, enhancing strength and improving response of the hydrogel become a main problem in the expansion of its applications. It is reported that the IPN structure could make up this disadvantage, because this technology can offer the possibility to obtain materials with combined properties of the components, in semiIPNs, one of the two polymers has a linear structure; in IPNs, both polymers have crosslinked structures [8][9][10][11][12][13][14][15] .…”

Light Harvesting and Efficient Energy Transfer in Dendritic Systems: New Strategy for Functionalized Near‐Infrared BF2‐Azadipyrromethenes

“…Variations in these parameters produce interesting structural changes, which could eventually be important for biomedical applications. As thermosensitive hydrogels we can mention N ‐substituted acrylamide derivatives such as poly( N ‐isopropylacrylamide),9–11 poly( N,N ‐diethylacrylamide),12 methylacrylamide,13 partially hydrolysed polyacrylamide,14 agarose15 and poly( N,N ‐diethylacrylamide‐ co ‐ N ‐isopropylacrylamide) 16. Copolymerization of acrylamide with more hydrophilic monomers, such as acrylic acid17 or sodium acrylate,18 has also been reported.…”

Preparation and properties of poly(N‐isopropylacrylamide)/poly(N‐isopropylacrylamide) interpenetrating polymer networks for drug delivery

“…Copolymerization with a hydrophobic monomer or the formation of an interpenetrating polymer network (IPN) may lead to a higher mechanical strength in comparison with that of a homopolymer network of PNIPA 18–20. Modifications of the PNIPA hydrogel through the formation of an IPN structure have been found to enhance the mechanical properties of the PNIPA hydrogel 19–23. Okano et al21, 22 prepared poly(ethylene oxide‐dimethylsiloxane‐ethylene oxide)/poly( N ‐isopropyl acrylamide) IPN hydrogels and investigated the release behavior of indomethacin and ketoprofen.…”