Micromechanical properties of poly(N-isopropylacrylamide) hydrogel microspheres determined using a simple method--颗粒学报PARTICUOLOGY

Yuan, M., Ju, X., Xie, R., Wang, W., & Chu, L. (2015). Micromechanical properties of poly(N-isopropylacrylamide) hydrogel microspheres determined using a simple method. Particuology, 19, 164–172. https://doi.org/10.1016/j.partic.2014.07.002

Micromechanical properties of poly(N-isopropylacrylamide) hydrogel microspheres determined using a simple method

Mei Yuan, Xiaojie Ju^*, Rui Xie, Wei Wang, Liangyin Chu

School of Chemical Engineering, Sichuan University, Chengdu 610065, China

10.1016/j.partic.2014.07.002

Volume 19, April 2015, Pages 164-172

Received 3 April 2014, Revised 3 July 2014, Accepted 9 July 2014, Available online 23 October 2014.

E-mail: juxiaojie@scu.edu.cn

Highlights

• A simple method was developed to study micromechanical properties of hydrogel microspheres.

• Force-deformation data of PNIPAM hydrogel microspheres fitted well with Hertz theory.

• Compositions of PNIPAM microspheres significantly affected the micromechanical properties.

• Microsphere with larger thermo-responsive volume change had lower modulus of elasticity.

• Moduli of elasticity of PNIPAM microspheres at 37 °C was much larger than that at 25 °C.

Abstract

Temperature-responsive poly(N-isopropylacrylamide) (PNIPAM) hydrogel microspheres have attracted extensive attention because of their promising diverse biomedical applications. A quantitative understanding of the micromechanical properties of these microspheres is essential for their practical application. Here, we report a simple method for the characterization of the elastic properties of PNIPAM hydrogel microspheres. The results show that PNIPAM hydrogel microspheres exhibit elastic deformation and the obtained force-deformation experimental data fits the Hertz theory well. The moduli of elasticity of the PNIPAM hydrogel microspheres prepared under different conditions were systematically investigated in this work for the first time. The PNIPAM hydrogel microsphere composition significantly affects their micromechanical properties and their temperature sensitivity behavior. PNIPAM hydrogel microspheres with a larger equilibrium volume change have a lower modulus of elasticity. The modulus of elasticity of the PNIPAM hydrogel microspheres at body temperature (37 °C, above the lower critical solution temperature (LCST) of PNIPAM) is much higher than that at room temperature (25 °C, below the LCST of PNIPAM) because of thermo-induced volume shrinkage and an increase in stiffness. These results provide valuable guidance for the design of smart materials for practical biomedical applications. Moreover, the simple microcompression method presented here also provides a versatile way to investigate the micromechanical properties of microscopic biomedical materials.

Graphical abstract

Keywords

Poly(N-isopropylacrylamide); Microspheres; Micromechanical properties; Modulus of elasticity; Temperature-responsive volume change; Lower critical solution temperature

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