Mechanics from Calorimetry: A New Probe of Elasticity for Responsive Hydrogels

TL;DR

This paper introduces a calorimetry-based method to measure the elastic modulus of thermoresponsive hydrogels, linking thermal and mechanical properties for improved characterization of small or irregularly shaped particles.

Contribution

It presents a novel approach using differential scanning calorimetry to determine hydrogel elasticity, validated against traditional osmotic compression tests.

Findings

Calorimetry can effectively measure the elastic modulus of thermoresponsive hydrogels.

The method is suitable for submicron-sized or irregularly shaped particles.

Thermal and mechanical property changes are thermodynamically linked.

Abstract

Temperature-sensitive hydrogels based on polymers such as poly(N-isopropylacrylamide) (PNIPAM) undergo a volume phase transition in response to changes in temperature. During this transition, distinct changes in both thermal and mechanical properties are observed. Here, we illustrate and exploit the inherent thermodynamic link between thermal and mechanical properties by showing that the compressive elastic modulus of PNIPAM hydrogels can be probed using differential scanning calorimetry. We validate our approach by using conventional osmotic compression tests. Our method could be particularly valuable for determining the mechanical response of thermosensitive submicron-sized and/or oddly shaped particles, to which standard methods are not readily applicable.