Multi-Responsive Polysiloxane/Poly(N-isopropylacrylamide) Interpenetrating Networks Containing Urea and Thiourea Groups.

Junta Sano,Shigeki Habaue

doi:10.3390/polym12051175

Abstract

Novel interpenetrating polymer networks (IPNs) were synthesized from N-isopropylacrylamide (NIPAM) and polysiloxanes containing a urea or thiourea side group, in addition to the silanol residue, through two reactions, such as the radical gelation of NIPAM and the condensation of silanols to form a siloxane linkage. The obtained IPNs showed a typical temperature-responsive volume change in water based on the constructed poly-NIPAM gel component. In addition, the characteristic color and volume changes responding to chemical stimuli, such as acetate and/or fluoride ions, based on the introduced urea and thiourea groups onto the polysiloxane gel were observed in N,N-dimethylformamide.

Highlights

Interpenetrating polymer networks (IPNs) are a gel with an interesting structure, which consists of two polymeric components as an entangled network structure without covalent bonds crosslinking each other
We demonstrated the synthesis of a full IPN composed of polysiloxane and acrylamide gels through the novel simultaneous method, where both the radical gelation of acrylamides in the presence of a crosslinking agent and the condensation reaction between silanols on the polysiloxane proceeded simultaneously [12]
The obtained model gel as well as GNIPAM were brittle; the gels synthesized using the simultaneous gelation method showed an improved mechanical property, which is one of the typical characteristics observed for full IPNs [1,2]. These results suggest that the gel structure of the polysiloxane constructed during the gelation significantly affects the properties of the IPNs

Summary

Introduction

Interpenetrating polymer networks (IPNs) are a gel with an interesting structure, which consists of two polymeric components as an entangled network structure without covalent bonds crosslinking each other. Stimuli-responsive gels are typically capable of controlling the volume change in response to various external conditions, such as temperature, pH, and chemicals. The IPNs can be applied to dual-responsive materials, which respond to two factors. Among such smart IPN gels, temperature- and pH-responsive hydrogels have been extensively studied because these two factors can be controlled in an aqueous phase [7,8,9,10,11]. The smart IPNs that multiply responding to the external stimuli in various media are still limited mainly due to difficulty in synthesizing the designed IPN structure

Methods

Results

Conclusion