title: Rapid stiffening of a microfluidic endoskeleton via frontal polymerization.
abstract: Materials capable of rapidly modifying their physical properties in response to stimuli are desirable for on-demand deployment and adaptive engineering structures. Frontal polymerization is a self-propagating reaction that can quickly transform liquid reactants into solid products. In this contribution, we demonstrate that frontal polymerization enables facile, rapid stiffening of a vascular network embedded in a flexible matrix. Systematic variation of the vascular architecture shows that polymerization fronts in a polydimethylsiloxane (PDMS) matrix are self-propagating in channels as small as 838 μm and even when curves, branch points and converging geometries are present. After polymerization the composite structure was dramatically stiffened (up to 18 times the original Young's modulus) based on tensile testing results. This work demonstrates the use of frontal polymerization as an efficient methodology for transforming flexible materials into functional supports or surfaces through endoskeletal stiffening.
authors.affiliation: Departments of Chemistry, ‡Mechanical Science and Engineering, §Aerospace Engineering, and ⊥Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Robertson
authors.forename: Hector Lopez
authors.initials: HL
authors.lastname: Hernandez
authors.forename: Scott R
authors.initials: SR
authors.lastname: White
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Moore
keywords: frontal polymerization; microfluidic endoskeleton; rapid stiffening; shape fixing