Highly branched poly(ether ester)s via cyclization-free melt condensation of A 2 oligomers and B 3 monomers

Serkan Unal, Timothy Edward Long

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

This paper reports the first synthesis of A 2 + B 3 highly branched polyesters with the minimal formation of cyclics in the absence of a polymerization solvent. Highly branched poly(ether ester)s were synthesized in the melt phase using an oligomeric A 2 + B 3 polymerization strategy. Condensation of poly(propylene glycol) (M n ∼1060 g/mol) and trimethyl 1,3,5-benzenetricarboxylate in the presence of titanium tetraisopropoxide generated highly branched structures with high molar mass when the reaction was stopped immediately prior to the gel point. Size exclusion chromatography (SEC) and 1H NMR spectroscopy were used to monitor molar mass as a function of monomer conversion and to determine the gel point. Monomer conversions at both the theoretical and experimental gel points for an A 2.B 3 = 1:1 molar ratio agreed well. Thus, cyclization reactions, which are common in A 2 + B 3 polymerization in solution, were negligible in the melt phase. The degree of branching (DB) increased with an increase in monomer conversion and molar mass, and the final product contained 20% dendritic units. Monofunctional end-capping reagents were also used to avoid gelation in the melt phase, and high molar mass final products were obtained with nearly quantitative monomer conversion in the absence of gelation. The presence of a monofunctional comonomer did not affect the molar mass increase or the formation of branched structures due to desirable ester interchange reactions.

Original languageEnglish
Pages (from-to)2788-2793
Number of pages6
JournalMacromolecules
Volume39
Issue number8
DOIs
Publication statusPublished - 2006 Apr 18
Externally publishedYes

Fingerprint

Propylene Glycol
Molar mass
Cyclization
Glycols
Oligomers
Ether
Propylene
Condensation
Ethers
Esters
Monomers
Gels
Polymerization
Gelation
Polyesters
Size exclusion chromatography
Interchanges
Nuclear magnetic resonance spectroscopy
Titanium

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Highly branched poly(ether ester)s via cyclization-free melt condensation of A 2 oligomers and B 3 monomers. / Unal, Serkan; Long, Timothy Edward.

In: Macromolecules, Vol. 39, No. 8, 18.04.2006, p. 2788-2793.

Research output: Contribution to journalArticle

Unal, Serkan ; Long, Timothy Edward. / Highly branched poly(ether ester)s via cyclization-free melt condensation of A 2 oligomers and B 3 monomers. In: Macromolecules. 2006 ; Vol. 39, No. 8. pp. 2788-2793.
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