Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(<italic style="font-style: italic">N</italic>-isopropylacrylamide)-based Hydrogels

Li-Fang Ma; Di-Ming Chen; Ye Xu; Chun-Jing Tao; Yu-Bo Fan

doi:10.1007/s10118-025-3422-7

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Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(N-isopropylacrylamide)-based Hydrogels

RESEARCH ARTICLE | Updated：2025-10-30

- Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(N-isopropylacrylamide)-based Hydrogels
- Chinese Journal of Polymer Science Vol. 43, Issue 11, Pages: 2061-2072(2025)
- Affiliations：
  
  a.School of Biological Science and Medical Engineering, School of Engineering Medicine, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100191, China
  b.National Research Center for Rehabilitation Technical Aids, Beijing 100176, China
  c.School of Engineering Medicine, Beijing Advanced Innovation Centre for Biomedical Engineering, Beihang University, Beijing 100191, China
- Author bio：
  
  chunjingtao@buaa.edu.cn (C.J.T.)
  yubofan@buaa.edu.cn (Y.B.F.)
- Funds：
- DOI：10.1007/s10118-025-3422-7
  CLC：
- Received：04 July 2025，
  
  Accepted：02 August 2025，
  
  Published Online：11 October 2025，
  
  Published：05 November 2025
- Accepted：
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Ma, L. F.; Chen, D. M.; Xu, Y.; Tao, C. J.; Fan, Y. B. Effect of molecular weight selection and relative humidity on the moisture absorption and desorption behavior of poly(N-isopropylacrylamide)-based hydrogels. Chinese J. Polym. Sci. 2025, 43, 2061–2072

Li-Fang Ma, Di-Ming Chen, Ye Xu, et al. Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(N-isopropylacrylamide)-based Hydrogels[J]. Chinese journal of polymer science, 2025, 43(11): 2061-2072.
Ma, L. F.; Chen, D. M.; Xu, Y.; Tao, C. J.; Fan, Y. B. Effect of molecular weight selection and relative humidity on the moisture absorption and desorption behavior of poly(N-isopropylacrylamide)-based hydrogels. Chinese J. Polym. Sci. 2025, 43, 2061–2072 DOI： 10.1007/s10118-025-3422-7.

Li-Fang Ma, Di-Ming Chen, Ye Xu, et al. Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(N-isopropylacrylamide)-based Hydrogels[J]. Chinese journal of polymer science, 2025, 43(11): 2061-2072. DOI： 10.1007/s10118-025-3422-7.

摘要

Poly(N-isopropylacrylamide)-based hydrogels were prepared using the precipitation polymerization method. The hygroscopic properties of the hydrogel materials were compared and analyzed under conditions below and above the lower critical solution temperature (LCST). The effects of molecular weight selection and relative humidity on the hygroscopic and desiccative behavior of the hydrogel materials were systematically investigated.

Abstract

Temperature-sensitive random copolymerized nanohydrogels were prepared

via

a one-pot polymerization method using

-isopropylacrylamide (NIPAM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) as raw materials. Transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) analyses revealed the partially crystallized porous nanostructure o

f the gels

which is consistent with the characteristics of porous nanohydrogel materials. The low-molecular-weight polymers exhibited enhancement and sharpening of the end group peaks in Fourier-transform infrared (FTIR)

X-ray photoelectron spectroscopy (XPS)

and nuclear magnetic resonance hydrogen (

H-NMR) spectra due to the high proportion of small molecules or low-molecular-weight chain segments. In turn

the high-molecular-weight polymers showed pronounced peaks in the main chain segments because of the long-chain effect. Hygroscopicity increased with the molecular weight of the selected polymers

but was inhibited by temperatures below the lower critical solution temperature (LCST). Meanwhile

moisture desorption was faster in low-molecular-weight samples

and the overall moisture desorption rate rose above the LCST value. According to the kinetic analysis

the moisture absorption process conformed to the quasi-primary or quasi-secondary kinetic model

whereas the moisture desorption followed the quasi-secondary model. Moisture cycling experiments showed that the material maintained stable moisture absorption and desorption performance after several cycles

which is essential for long-term cycling.

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Effect of Molecular Weight Selection and Relative Humidity on the Moisture Absorption and Desorption Behavior of Poly(N-isopropylacrylamide)-based Hydrogels

DOI：10.1007/s10118-025-3422-7

摘要

Abstract

关键词

Keywords

references