Photoactive polyesters containing o-nitro benzyl ester functionality for photodeactivatable adhesion

Stephen M. June, Takeo Suga, William H. Heath, Qin Lin, Rama Puligadda, Lei Yan, David Dillard, Timothy E. Long

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The fabrication of modern microelectronic silicon devices mechanically challenges these thin silicon substrates during manufacturing operations. Melt and solution polyesterification enabled the synthesis of polyesters containing photoreactive o-nitro benzyl ester units for use as a potential photocleavable adhesive. Melt transesterification provided a solvent-free method for synthesis of 2-nitro-p-xylylene glycol (NXG)-containing polyesters of controlled molecular weights. 1H NMR spectroscopy confirmed the chemical composition of the photoactive polyesters. Size exclusion chromatography (SEC) determined the number-average molecular weights (Mn) of the polyesters synthesized in the range of 6000 to 12000 g/mol. 1H NMR spectroscopy confirmed increasing levels of photocleavage of the o-nitro benzyl ester functionality with increasing exposure to broad wavelength UV irradiation, and exposure levels ranged from 0-187 J/cm2 UVA. Photocleaveage of approximately 90% of the o-nitro benzyl ester (ONB) units within the backbone of the polymer occurred at maximum dosage. Wedge fracture testing revealed approximately a two-fold decrease in fracture energy upon UV irradiation, suggesting that these structural adhesives offer potential for commercial "flip bonding" applications.

Original languageEnglish
Pages (from-to)548-558
Number of pages11
JournalJournal of Adhesion
Volume89
Issue number7
DOIs
Publication statusPublished - 2013 Jul 3
Externally publishedYes

Keywords

  • Melt transesterification
  • Micro-fabrication processes
  • Photoreactive
  • Polyester
  • Reversible adhesives
  • Structural adhesives
  • Temporary bonding

ASJC Scopus subject areas

  • Chemistry(all)
  • Mechanics of Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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