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  • Featured in Physics
  • Open Access

Hydroplasticity of Nanocrystal Films Induced by Mesopore Change

Siyuan Liu1, Yonggui Wang2, Yu Yin1, Xintong Meng1, Zhen Lang1, and Kai Zhang1,3,*

  • 1Sustainable Materials and Chemistry, Dept. Wood Technology and Wood-based Composites, University of Göttingen, Göttingen 37077, Germany
  • 2Key Laboratory of Bio-based Material Science and Technology (Ministry of Education), College of Material Science and Engineering, Northeast Forestry University, Hexing 26 Road, Harbin 150040, China
  • 3Wöhler Research Institute of Sustainable Chemistry (WISCh), Faculty for Chemistry, University of Göttingen, Göttingen 37077, Germany

  • *Contact author: kai.zhang@uni-goettingen.de
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Phys. Rev. X 16, 021026 – Published 5 May, 2026

DOI: https://doi.org/10.1103/vbxp-nz39

Abstract

Hydroplastification offers an eco-friendly route to plasticize hydrophilic polymers by enhancing chain mobility, yet it remains ineffective for rigid crystalline nanomaterials. Here, we report a novel plasticity mechanism governed by mesopores acting as structural free volume between rigid hydrophilic nanocrystals, cellulose nanocrystals (CNCs). During the mechanosorptive vapor training process to change the mesopores, the plasticity arises from a dynamic competition between external tensile stress and internal capillary forces. We establish a semiquantitative constitutive relationship revealing that the network’s wet-state yield strength is critically regulated by the aspect ratio and surface chemistry of the nanocrystals. Specifically, the weak acidity of carboxyl groups (pKa∼3.2) combined with high aspect ratios creates a defect-dominated soft skeleton; here, the internal Laplace pressure (∼26  MPa) exceeds the yield strength, driving the splitting of bottlelike mesopores into smaller domains until a geometric locking limit defined by the nanocrystal diameter is reached. In contrast, strong electrostatic repulsion from sulfonates (pKa∼1.0) or spatial jamming in short nanorods results in rigid networks that resist this capillary-driven densification. This novel hydroplastification mechanism by capitalizing on mesopores with competing capillary force, opposing network stress, and external stress enables shaping CNC films into stable geometries, rather than lattice disruption. Moreover, such findings extend hydroplasticity concepts to rigid matter, establishing mesopore engineering as a physical pathway to regulate the plasticity of crystalline nanomaterials.

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Physics Subject Headings (PhySH)

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Durable Green Plastic from Cellulose

Published 5 May, 2026

A hard and environmentally friendly plastic material is produced by subjecting cellulose crystals to humidity oscillations.

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Popular Summary

Achieving plasticity in rigid crystalline nanomaterials is a major challenge because they inherently fracture rather than flow under stress. We address this by developing a mechanosorptive “vapor training” protocol for one-dimensional nanocrystal material, cellulose nanocrystal films, supported by a constitutive model that links macroscopic shaping to mesoscopic pore evolution. We reveal that plasticity arises from a dynamic competition where internal capillary pressure (∼26  MPa) overcomes the network’s yield strength, a balance strictly regulated by the nanorod aspect ratio and surface chemistry. Specifically, we find that high aspect ratio rods with weak surface acidity form a soft skeleton that allows controlled pore collapse and reshaping, while short or chemically repulsive rods form rigid and locked networks. These results demonstrate a novel hydroplastic mechanism based on mesopore engineering, enabling the processing of rigid sustainable materials into complex geometries.

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Phys. Rev. X 16, 021026– Published 5 May, 2026
  • Received 9 July 2025
  • Accepted 5 March 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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