CO2-responsive poly(N,N-dimethylaminoethyl methacrylate) hydrogels with fast responsive rate

Xiao-Ying Li, Rui Xie, Feng Luo, Zhi-Han Jia, Kun Shi, Xiao-Jie Ju, Wei Wang, Zhuang Liu, Liang-Yin Chu

Index: 10.1016/j.jtice.2018.03.006

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Abstract

CO2-responsive hydrogels have attracted increasing and extensive attention from various fields such as sensors and controlled drug delivery systems. However, the traditional CO2-responsive hydrogels suffer from unsatisfied responsive rate, which has limited their practical applications. Herein, we report on novel CO2-responsive poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) hydrogels with fast responsive rate, which resulted from an open-celled porous structure inside the hydrogels. Oil-in-water emulsion templates prepared by microfluidic emulsification are used as porogens for synthesis of PDMAEMA hydrogels with open-celled porous structures. The open-celled porous structures provide numerous interconnected diffusion channels for the water transfer during the swelling process of PDMAEMA hydrogels. The effects of interconnectivity and size of pores on the CO2-responsive rate of hydrogels are systematically investigated. The results show that the responsive rates of open-celled porous PDMAEMA hydrogels are much faster than that of the normal ones during the dynamic swelling processes. The open-celled hydrogels with large pore size exhibit the dramatic swelling after bubbling CO2 for 20 s, and the maximum swelling rate is 30 times faster than that of normal hydrogels. The proposed new strategy for preparation of CO2-responsive hydrogels with fast responsive rate may provide ever better performances for CO2-responsive hydrogels in their myriad applications.