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2026 Vol.58, Issue 2 Preview Page

Original Paper

Mechanically Programmed Anisotropic CMCNF/PAA Hydrogels via Shear-Assisted Pre-Stretching for Rapid pH-Responsive Actuation
Zhaoyong Wu1
,
Junyi Li2
,
Ming He3†
1State Key Laboratory of Green Papermaking and Resource Recycling, Qilu University of Technology (Shandong Academy of Sciences), Graduate Student
2School of Materials Science and Engineering, Peking University, Postdoctoral Researcher
3State Key Laboratory of Green Papermaking and Resource Recycling, Qilu University of Technology (Shandong Academy of Sciences), Associate Professor
†Corresponding Author: E-mail: heming8916@qlu.edu.cn (Address: State Key Laboratory of Green Papermaking and Resource Recycling, Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250353, China)
30 April 2026. pp. 64-76
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Abstract

Conventional isotropic pH-responsive hydrogels often suffer from slow solvent transport, limited mechanical strength, and poorly controlled deformation, which restrict their applications in soft actuators and biomimetic systems. Herein, we report a mechanically programmed strategy to fabricate anisotropic carboxymethylated cellulose nanofibril/polyacrylic acid (CMCNF/PAA) hydrogels via synergistic shear-induced alignment and sequential pre-stretching. Shear flow first induces the high-aspect-ratio CMCNFs within the precursor, while subsequent pre-stretching further straightens and densifies the aligned framework, yielding a hierarchical anisotropic architecture without requiring external fields. As a result, the hydrogels exhibit pronounced mechanical anisotropy, with an approximately eightfold difference between the axial and transverse compression moduli, together with excellent cyclic stability, retaining about 92% of their actuation performance after 10 pH-switching cycles. The aligned nanochannels facilitate solvent transport and directional swelling, enabling a rapid actuation response that begins within 0.5 s and reaches a stable curled state within about 15–20 s under alkaline conditions and programmable bending deformation (curvature >200 m-1). By adjusting the shear rate (50–800 s-1) and the pre-stretch ratio (100–300%), the swelling ratio (300–1,200%) and the pH transition threshold (4.0–6.5) can be precisely tailored. Owing to their high cytocompatibility (cell viability >98%) structural programmability, and facile fabrication, these anisotropic CMCNF/PAA hydrogels provide a scalable platform for applications in soft actuators, tissue-mimetic scaffolds, and wearable devices.

Keywords
Nanocellulose
poly(acrylic acid)
anisotropy
shear alignment
pH-responsive hydrogels
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Information
  • Publisher :Korea Technical Association of The Pulp and Paper Industry
  • Publisher(Ko) :한국펄프종이공학회
  • Journal Title :Journal of Korea TAPPI
  • Journal Title(Ko) :펄프종이기술
  • Volume : 58
  • No :2
  • Pages :64-76
  • Received Date : 2026-03-12
  • Revised Date : 2026-04-09
  • Accepted Date : 2026-04-10
  • DOI :https://doi.org/10.7584/JKTAPPI.2026.4.58.2.64
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