Photoinduced Crosslinking of Polymers Containing Pendant Hydroxyl Groups by Using Bisbenzodioxinones

Abstract

In the present study, it has been demonstrated that polymers containing pendant hydroxyl groups can undergo photoinduced crosslinking upon irradiation in the presence of bifunctional benzodioxinone. Irradiation of the copolymers of 2‐hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) in dichloromethane and THF solutions or in films containing bisbenzodioxinone, namely 5‐[9‐(4‐oxo‐2,2‐diphenyl‐4H‐benzo[d][1,3]dioxin‐5‐yloxy) nonyloxy]‐2,2‐diphenyl‐4H‐benzo[d][1,3]dioxin‐4‐one resulted in the formation of insoluble networks. Model studies using monofunctional napthodioxinone, namely 7‐hydroxy‐2,2‐diphenyl‐4H‐naphtho[2,3‐d][1,3]dioxin‐4‐one, revealed that crosslinking occurs via inter‐chain ester formation between photochemically generated keten intermediates and pendant hydroxyl groups.magnified image

Photoinitiated Polymerization: Advances, Challenges, and Opportunities

“…It was shown 52 that structurally designed benzodioxinones liberate benzophenone only after stimulation by light which can further be excited to initiate free radical polymerization (Scheme 4). Liberation of both ketenes and benzophenone photoinitiator upon photolysis of benzodioxinones makes these compounds useful for cross-linking of hydroxyl-containing polymers 53 and also monofunctional vinyl monomers in the absence of a conventional photoinitiator and cross-linker. 54 Among type II photoinitiators, thioxanthone derivatives in conjunction with tertiary amines are efficient photoinitiators with absorption characteristics that compare favorably with benzophenones.…”

Orthogonal Synthesis of Block Copolymer via Photoinduced CuAAC and Ketene Chemistries

“…They can react with unsaturated compounds to produce the [2+2] cyclo‐adduct and nucleophiles like amine, alcohol, and acid to give an amide, ester, and anhydride analogue. For instance, the benzodioxinone moiety as a photolytic precursor of ketene has been incorporated into either polymer end‐ or side‐ groups to enable highly efficient postmodification reactions …”

The emerging utility of ketenes in polymer chemistry

“…The photochemically generated quinoketene was successfully coupled with the pendant alcohols of the HEMA comonomer, generating PMMA‐ graft ‐PS materials, although the highest grafting efficiency reported was 58%. The Yagci group extended this methodology by synthesizing bifunctional benzodioxinone small molecules and employing them to crosslink HEMA‐containing PMMA copolymers via photochemical quinoketene generation . Lastly, photochemically generated quinoketenes proved useful for generating polymer/silica composite materials.…”