Dissociative Carbamate Exchange Anneals 3D Printed Acrylates

Leslie S. Hamachi, Daniel A. Rau, Clay B. Arrington, Daylan T. Sheppard, David J. Fortman, Timothy E. Long, Christopher B. Williams, William R. Dichtel

Research output: Contribution to journalArticlepeer-review

Abstract

Relative to other additive manufacturing modalities, vat photopolymerization (VP) offers designers superior surface finish, feature resolution, and throughput. However, poor interlayer network formation can limit a VP-printed part's tensile strength along the build axis. We demonstrate that the incorporation of carbamate bonds capable of undergoing dissociative exchange reactions provides improved interlayer network formation in VP-printed urethane acrylate polymers. In the presence of dibutyltin dilaurate catalyst, the exchange of these carbamate bonds enables rapid stress relaxation with an activation energy of 133 kJ/mol, consistent with a dissociative bond exchange process. Annealed XY tensile samples containing a catalyst demonstrate a 25% decrease in Young's modulus, attributed to statistical changes in network topology, while samples without a catalyst show no observable effect. Annealed ZX tensile samples printed with layers perpendicular to tensile load demonstrate an increase in elongation at break, indicative of self-healing. The strain at break for samples containing a catalyst increases from 33.9 to 56.0% after annealing but decreases from 48.1 to 32.1% after annealing in samples without a catalyst. This thermally activated bond exchange process improves the performance of VP-printed materials via self-healing across layers and provides a means to change Young's modulus after printing. Thus, the incorporation of carbamate bonds and appropriate catalysts in the VP-printing process provides a robust platform for enhancing material properties and performance.

Original languageEnglish (US)
Pages (from-to)38680-38687
Number of pages8
JournalACS Applied Materials and Interfaces
Volume13
Issue number32
DOIs
StatePublished - Aug 18 2021

Keywords

  • 3D printing
  • additive manufacturing
  • covalent adaptable network
  • dissociative carbamate exchange
  • polyurethane
  • vat photopolymerization

ASJC Scopus subject areas

  • Materials Science(all)

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