Influence of the Nature of Aliphatic Hydrophobic Physical Crosslinks on Water Crystallization in Copolymer Hydrogels

The local environment within a hydrogel influences the properties of water, including the propensity for ice crystallization. Water-swollen amphiphilic copolymers produce tunable nanoscale environments, which are defined by hydrophobic associations, for the water molecules. Here, the antifreeze properties for equilibrium-swollen amphiphilic copolymers with a common hydrophilic component, hydroxyethyl acrylate (HEA), but associated through crystalline (octadecyl acrylate, ODA) or rubbery (ethylhexyl acrylate, EHA) hydrophobic segments, are examined. Differences in the efficacy of the associations can be clearly enunciated from compositional solubility limits for the copolymers in water (<2.6 mol % ODA vs ≤14 mol % EHA), and these differences can be attributed to the strength of the association. The equilibrium-swollen HEA-ODA copolymers are viscoelastic solids, while the swollen HEA-EHA copolymers are viscoelastic liquids. Cooling these swollen copolymers to nearly 200 K induces some crystallization of the water, where the fraction of water frozen depends on the details of the nanostructure. Decreasing the mean free path of water by increasing the ODA composition from 10 to 25 mol % leads to fractionally more unfrozen water (66-87%). The swollen HEA-EHA copolymers only marginally inhibit ice (<13%) except with 45 mol % EHA, where nearly 60% of the water remains amorphous on cooling to 200 K. In general, the addition of the EHA leads to less effective ice inhibition than analogous covalently crosslinked HEA hydrogels (19.9 ± 1.8%). These results illustrate that fluidity of confining surfaces can provide pathways for critical nuclei to form and crystal growth to proceed.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in The Journal of Physical Chemistry B, copyright © 2022 American Chemical Society after peer review and technical editing by the publisher.

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Work Title Influence of the Nature of Aliphatic Hydrophobic Physical Crosslinks on Water Crystallization in Copolymer Hydrogels
Access
Open Access
Creators
  1. Pablo I. Sepulveda-Medina
  2. Chao Wang
  3. Ruipeng Li
  4. Masafumi Fukuto
  5. Bryan D. Vogt
Keyword
  1. Crystalline crosslinks
  2. Ice
  3. SAXS
  4. Nanoconfinement
  5. Supercooled water
License In Copyright (Rights Reserved)
Work Type Article
Publisher
  1. Journal of Physical Chemistry B
Publication Date July 14, 2022
Publisher Identifier (DOI)
  1. https://doi.org/10.1021/acs.jpcb.2c02438
Deposited May 06, 2024

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Version 1
published

  • Created
  • Added ODAEHA_accepted-1.pdf
  • Added Creator Pablo I. Sepulveda-Medina
  • Added Creator Chao Wang
  • Added Creator Ruipeng Li
  • Added Creator Masafumi Fukuto
  • Added Creator Bryan D. Vogt
  • Published
  • Updated
  • Updated Keyword Show Changes
    Keyword
    • Crystalline crosslinks, Ice, SAXS, Nanoconfinement, Supercooled water