Cyclo-oligomerization of hydroxyl-containing mono-functional benzoxazines: a mechanism for oligomer formation. Issue 13 (18th March 2020)

• Record Type: Journal Article
• Authors: Zhen, Hecheng; Yang, Huiyun; Wang, Mei; Lu, Guosheng; Liu, Yanfang; Run, Mingtao
• Is Part Of: Polymer chemistry. Volume 11:Issue 13(2020)
• Page Start: 2325
• Page End: 2331
• Publication Date: 2020-03-18
• Subjects: Polymers -- Periodicals; Macromolecules -- Periodicals; Polymerization -- Periodicals; 547.705
• DOI: 10.1039/d0py00047g
• Languages: English
• ISSNs: 1759-9954

Abstract

Abstract : The oligomerization of mono-functional benzoxazines is demonstrated with intermolecular cyclization via a Mannich bridge structure as the primary reaction pathway. Abstract : The oligomerization of mono-functional benzoxazines is demonstrated with intermolecular cyclization via a Mannich bridge structure as the primary reaction pathway. The structures of oligomers of mono-functional benzoxazines were previously thought to be benzoxazine dimers stabilized by inter- and intramolecular hydrogen bonding. This study is based on four hydroxyl-containing mono-functional benzoxazines synthesized from phenol, o -allylphenol, o -cresol, p -cresol, diglycolamine, and paraformaldehyde. A reaction mechanism is proposed that ortho - and para -substituted-phenol-based mono-functional benzoxazines undergo thermally activated ring-opening cyclo-oligomerization (ROCO) and ring-opening oligomerization (ROO), whereas their phenol-based counterpart polymerizes into polybenzoxazine following ROCO and ROO, which is evidenced by the data of 1 H and 13 C nuclear magnetic resonance spectra, Fourier transform infrared spectra, size exclusion chromatograms, and mass spectra of thermally treated samples.