Synthesis and cleavage of core-labile poly(alkyl methacrylate) star polymers

Lars Kilian, Zhen He Wang, Timothy E. Long

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Core-cleavable star polymers were synthesized by the coupling of living anionic poly(alkyl methacrylate) arms with either dicumyl alcohol dimethacrylate (DCDMA) or 2,5-dimethyl-2,5-hexanediol dimethacrylate (DHDMA). This synthetic methodology led to the formation of star polymers that exhibited high molecular weights and relatively narrow molecular weight distributions. The labile tertiary alkyl esters in the DCDMA and DHDMA star polymer cores were readily hydrolyzed under acidic conditions. High-molecular-weight star polymer cleavage led to well-defined arm polymers with lower molecular weights. Hydrolysis was confirmed via 1H NMR spectroscopy and gel permeation chromatography. Thermogravimetric analysis (TGA) of the star polymers demonstrated that the DCDMA and DHDMA star polymer cores also thermally degraded in the absence of acid catalysts at 185 and 220°C, respectively, and the core-cleavage temperatures were independent of the arm polymer composition. The difference in the core-degradation temperatures was attributed to the increased reactivity of the DCDMA-derived cores. TGA/mass spectrometry detected the evolution of the diene byproduct of the core degradation and confirmed the proposed degradation mechanism. The DCDMA monomer exhibited a higher degradation rate than DHDMA under identical reaction conditions because of the additional resonance stabilization of the liberated byproduct, which made it a more responsive cleavable coupling monomer than DHDMA.

Original languageEnglish (US)
Pages (from-to)3083-3093
Number of pages11
JournalJournal of Polymer Science, Part A: Polymer Chemistry
Volume41
Issue number19
DOIs
StatePublished - Oct 1 2003
Externally publishedYes

Keywords

  • Anionic polymerization
  • Degradation
  • Star polymers

ASJC Scopus subject areas

  • Polymers and Plastics
  • Organic Chemistry
  • Materials Chemistry

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