Thermoresponsive Stiffening with Microgel Particles in a Semiflexible Fibrin Network

Gaurav Chaudhary, Ashesh Ghosh, N. Ashwin Bharadwaj, Jin Gu Kang, Paul V. Braun, Kenneth S. Schweizer, Randy H. Ewoldt

Research output: Contribution to journalArticlepeer-review


We report temperature-responsive soft composites of semiflexible biopolymer networks (fibrin) containing dispersed microgel colloidal particles of poly(N-isopropylacrylamide) (pNIPAM) that undergo a thermodynamically driven deswelling transition above the lower critical solution temperature. Unlike standard polymer-particle composites, decreasing the inclusion volume of the particles (by increasing temperature) is concomitant with a striking increase of the overall elastic stiffness of the composite. We observe such a behavior over a wide composition space. The composite elastic shear modulus reversibly stiffens by up to 10-fold over a small change in temperature from 25 to 35 °C. In isolation, the fibrin network and microgel suspension both soften with increased temperature, making the stiffening of the composites particularly significant. We hypothesize that stiffening is caused by the shrinking microgel particles that deform fibrin filaments, and modify the network structure. We develop a phenomenological model that quantifies this hypothesis, and the derived predictions are qualitatively consistent with our experimental data.

Original languageEnglish (US)
Pages (from-to)3029-3041
Number of pages13
Issue number8
StatePublished - Apr 23 2019

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry


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