Copolymerization of 9‐anthrylmethyl methacrylate with N‐phenylmaleimide

Abstract

The radical copolymerization of 9-anthrylmethyl methacrylate (1) with N-phenylmaleimide (2), initiated by 2,2 '-azoisobutyronitrile at 60 "C in 1 ,Cdioxane, was investigated. Simultaneously with the copolymerization a Diels-Alder cycloaddition of 2 to the anthracene nucleus takes place as side reaction. A charge transfer complex formation between the two monomers was evidenced by 'H NMR spectroscopy. The stability constant of the complex, which is an intermediate in the cycloaddition reaction, was found to be 0,05 1 . mol-' . C. I. Simionescu, M. Grigoras, G. OnofreiThe present paper deals with the radical copolymerization of the electron donor/ electron acceptor monomer pair 9-anthrylmethyl methacrylate (l)/N-phenylmaleimide (2), which can form a Diels-Alder cycloadduct (3). Experimental partMaterials: 9-Anthrylmethyl methacrylate (1) was obtained from the reaction of methacryloyl chloride with 9-anthranylmethanol'). N-Phenylmaleimide (2) was synthesized from maleic anhydride and aniline in a two stage reaction, according to the original method developed by Searle6). The monomers were recrystallized twice from methanol.The Diels-Alder cycloadduct (3) was synthesized by heating the two compounds (1,4dioxane solution, 0,5 mol/l total concentration) in a 1 : 1 mole ratio at 60°C for 24 h. After solvent evaporation, the adduct was recrystallized from methanol. The yield was quantitative.Copolymerization: Copolymerization reactions were carried out at 60 "C in sealed ampoules using 1,rl-dioxane as solvent. The total concentration of monomers was 0,5 mol/l in all cases, and the copolymer composition was varied by the ratio of the two monomers. 2,2'-Azoisobutyronitrile (AIBN) was used as initiator (1 mol-Yo related to the monomers) (Tab. 1). The copolymers were precipitated with methanol, filtered off and dried.The total content of monomeric units of 2 in the copolymers was obtained from the nitrogen analysis and the content of anthranyl groups was estimated from UV spectroscopy using the 390 nm absorption band.

Maleimide‐Functionalized Poly(2‐Oxazoline)s and Their Conjugation to Elastin‐Like Polypeptides

“…To make the maleimide more nucleophilic, the imide proton can be readily removed by sufficiently strong bases, such as K 2 CO 3 . However, maleimide cannot be used as a termination reagent as it readily reacts with the 2‐oxazoline monomer and the propagating species . To protect the functionality, the [4+2] Diels–Alder (DA) reaction between furan and maleimide was chosen (Scheme a).…”

Synthesis and polymerization of anthracene‐based itaconimides

“…The reaction was carried out thermally or by using Lewis acids as catalysts and is occasionally accompanied by side reactions such as radical polymerization or electrophilic substitution 27. When the double bond is activated by two electron withdrawing carbonyl groups, ie N ‐(1‐ anthryl or 2‐ anthryl) maleimide, the reactivity in Diels–Alder cycloaddition is so high that pure monomers free of cycloadduct oligomers are hard to obtain due to their spontaneous self‐polymerization by (2 + 4) cycloaddition reactions during the purification process 28–30…”

Copolymerization of a bisanthracene compound with bismaleimides by Diels–Alder cycloaddition

“…Also, a cycloaddition reaction between comonomers, as a side reaction besides the main copolymerization reaction, was evidenced in copolymerization of 9‐anthrylmethyl methacrylate with maleic anhydride and N ‐phenylmaleimide 13. 14 The modification of polymers having anthracene or fumaroyl moieties in the main chain by Diels–Alder reactions with maleimide derivatives and anthracene, respectively, has been reported 15. 16 In both cases the reaction is thermally reversible; at 250–300 °C a retro Diels–Alder reaction takes place.…”