Photoinitiated Free Radical Polymerization Using Benzoxazines as Hydrogen Donors

Abstract

Summary: Free radical polymerization of methyl methacrylate (MMA) is initiated upon irradiation at λ > 350 nm in CH2Cl2 that contains benzoxazine (P‐a) and one of the following photosensitizers: benzophenone (BP), thioxanthone (TX), 2‐chlorothioxanthone (CTX), 2‐isopropyl thioxanthone (ITX), and camphorquinone (CQ). The postulated mechanism is based on the intermolecular reaction of the excited photosensitizer with the tertiary amino moiety of the ground state P‐a and a subsequent hydrogen abstraction reaction. The resulting aminoalkyl radicals initiate the polymerization. The incorporation of P‐a groups into polymers is demonstrated by spectroscopic methods. The possibility of deep curing using the described photoinitiating system followed by the thermal ring opening of the incorporated P‐a groups is also demonstrated.

Integrating plant oils into thermally curable main-chain benzoxazine polymers via ADMET polymerization

“…Alternatively, the design of inherently tough polybenzoxazines by preparing benzoxazine monomers [13][14][15] or preferably prepolymers containing flexible segments has also been proposed. Thus, developing thermally curable polymeric precursors with benzoxazine units either as side chain [16] or as chain-end [17][18][19][20] or in main chain [21][22][23][24][25][26][27][28][29] some properties that are the combination of thermoplastic and thermosetting polymers such as processability, flexibility, high crosslinking density after cure, reductions in the vapor pressure during process and fragility for cured-structures are transferred to the cured resin. Although a wide range of polycondensation chemistries [30] such as polyester synthesis, hydrosilylation, Diels-Alder and [3+2] Huisgen type click reactions and Sonogashira coupling have been utilized to achieve this goal, to the best of our knowledge, there is no report on the synthesis of benzoxazine functionalized polymers via acyclic diene metathesis (ADMET) polymerization.…”

Thermal degradation of polysiloxane and polyetherester containing benzoxazine moieties in the main chain

“…We have previously synthesized [17][18][19][20] macromonomers containing one or two benzoxazine functionalities per chain of conventional polymers, namely polystyrene [17], poly(-caprolactone) [18], poly(methyl methacrylate) [19] and poly(propylene oxide) [20]. Thermally activated ring-opening copolymerization of these macromonomers yielded cross-linked polybenzoxazines with dangling chains [21].…”

Thiol reactive polybenzoxazine precursors: A novel route to functional polymers by thiol-oxazine chemistry

“…Therefore, a vast molecular design is possible for polybenzoxazine thermosettings. The synthesis of polybenzoxazine is also simple, since it is thermally induced ring opening polymerization of 1,3-benzoxazine monomers which can be accomplished without any initiator or curing agent (Scheme 1) [24][25][26][27][28][29][30][31][32]. The polymerization temperature of benzoxazine monomers vary between 160 and 250°C depending on the functional groups on the http://dx.doi.org/10.1016/j.eurpolymj.2015.02.030 0014-3057/Ó 2015 Elsevier Ltd. All rights reserved.…”