New zinc complexes derived from "self-adaptable" acyclic diiminodipyrromethanes as potent catalysts for the reduction of curing temperature of bisphenol-A/F benzoxazines.

Autor: Loke SK; Division of Chemistry, Department of Sciences and Humanities, Vignan's Foundation for Science Technology and Research (Deemed to be University) Vadlamudi Guntur-522213 Andhra Pradesh India ravikottalanka@gmail.com +91 863 2344 707 +91 863 2344 700., Pagadala E; Division of Chemistry, Department of Sciences and Humanities, Vignan's Foundation for Science Technology and Research (Deemed to be University) Vadlamudi Guntur-522213 Andhra Pradesh India ravikottalanka@gmail.com +91 863 2344 707 +91 863 2344 700., Devaraju S; Division of Chemistry, Department of Sciences and Humanities, Vignan's Foundation for Science Technology and Research (Deemed to be University) Vadlamudi Guntur-522213 Andhra Pradesh India ravikottalanka@gmail.com +91 863 2344 707 +91 863 2344 700., Srinivasadesikan V; Division of Chemistry, Department of Sciences and Humanities, Vignan's Foundation for Science Technology and Research (Deemed to be University) Vadlamudi Guntur-522213 Andhra Pradesh India ravikottalanka@gmail.com +91 863 2344 707 +91 863 2344 700., Kottalanka RK; Division of Chemistry, Department of Sciences and Humanities, Vignan's Foundation for Science Technology and Research (Deemed to be University) Vadlamudi Guntur-522213 Andhra Pradesh India ravikottalanka@gmail.com +91 863 2344 707 +91 863 2344 700.
Jazyk: angličtina
Zdroj: RSC advances [RSC Adv] 2020 Oct 01; Vol. 10 (60), pp. 36275-36286. Date of Electronic Publication: 2020 Oct 01 (Print Publication: 2020).
DOI: 10.1039/d0ra07837a
Abstrakt: The simple modification of the Schiff-base ligands often brings significant changes in the coordination properties of the metal-complexes, providing newer prospects for their unexplored applications. In this context, the present work utilized the "self-adaptable" acyclic diiminodipyrromethane Schiff's bases (2a and 2b) for the synthesis of their Zn-based complexes and explored their potential in the ring-opening polymerization of benzoxazines. The two zinc complexes of composition [Zn{(Ph)(CH 3 )C(2,6- i Pr 2 C 6 H 3 -N[double bond, length as m-dash]CH-C 4 H 2 N)(2,6- i Pr 2 C 6 H 3 -N[double bond, length as m-dash]CH-C 4 H 2 NH)} 2 ] (3) and [ZnCl 2 {(Ph)(CH 3 )C(Ph 3 C-NH[double bond, length as m-dash]CH-C 4 H 2 N) 2 }] (4) were synthesized in good yields, and the structures were confirmed by single crystal X-ray diffraction (XRD). Later, zinc complexes (3 & 4) were used as catalysts to reduce the curing (ring-opening polymerization) temperature of benzoxazine monomers such as Bisphenol-A (BA-a) and Bisphenol-F (BF-a) benzoxazines. Dynamic scanning calorimetry (DSC) studies revealed that the on-set curing ( T p ) temperatures were reasonably decreased upto 20% for the benzoxazines. Furthermore, the thermal stabilities of the polybenzoxazines (PBzs) derived in the presence of zinc catalysts (3 and 4) were compared with PBz obtained in the absence of catalyst under similar conditions. The thermal studies reveled that there is no significant changes in the initial degradation of polymers. However, the thermal stability in terms of char yields at 800 °C improved upto 10-21% for the bisphenol-A/F benzoxazines.
Competing Interests: There are no conflicts to declare.
(This journal is © The Royal Society of Chemistry.)
Databáze: MEDLINE
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