Radical copolymerization ofN-phenylmaleimide and diene monomers in competition with diels-alder reaction

Abstract

Radical copolymerization of N‐phenylmaleimide (PhMI) is carried out with various diene monomers including naturally occurring compounds and the copolymers are efficiently produced by the suppression of Diels–Alder reaction as the competitive side reaction. Diene monomers with an exomethylene moiety and a fixed s‐trans diene structure, such as 3‐methylenecyclopentene and 4‐isopropyl‐1‐methyl‐3‐methylenecyclohexene, exhibit high copolymerization reactivity to produce a high‐molecular‐weight copolymer in a high yield. The copolymerization of sterically hindered noncyclic diene monomers, such as 2,4‐dimethyl‐1,3‐pentadiene and 2,4‐hexadiene, also results in the formation of a high‐molecular‐weight copolymer in a moderate yield. The NMR spectroscopy reveals that the obtained copolymers consist of predominant 1,4‐repeating structures for the corresponding diene unit. The copolymers have excellent thermal stability, that is, an onset temperature of decomposition over 330 °C and a glass transition temperature over 130 °C. The copolymerization reactivity of these diene monomers is discussed based on the results of the DFT calculations. The efficient copolymer formation in competition with Diels–Alder addition is investigated under various conditions of the temperature, solvents, and initiators used for the copolymerization. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 3616–3625.

Heat resistant and transparent organic–inorganic hybrid materials composed of N‐allylmaleimide copolymer and random‐type SH‐modified silsesquioxane

“…Recently, transparent polymers with a high glass transition temperature ( T g ) and a high onset temperature for decomposition have become important because they are key materials for electronic and photonic applications . N‐Substituted maleimides (RMIs) copolymerize with various kinds of vinyl monomers in the presence of a radical initiator to give copolymers with excellent thermal stabilities . For example, the copolymerization of the RMIs with isobutene provided an alternating copolymer with an excellent thermal stability, transparency, and mechanical properties (Scheme ) .…”

Synthesis and Ozone Degradation of Alternating Copolymers ofN‐Substituted Maleimides with Diene Monomers

“…The reactions between PhMI and PD in the absence of a radical initiator was analyzed by 1 H NMR spectroscopy under the following conditions; [PhMI] = [PD] = 0.5 mol L −1 in chloroform at 30 °C. The yield of Diels–Alder product was 24% after reaction for 6 h ( Figure ), being higher than for the results for the reaction of PhMI and DMPD under similar conditions (≈10%) . Diels–Alder adducts obtained from PD can participate in propagation during copolymerization although the reactivity of internal olefins is considered to be low.…”

“…[22][23][24] More recently, radical copolymerization of PhMI with several diene monomers was carried out under various reaction conditions as an attempt for the synthesis of high-molecular-weight copolymers by suppression of Diels-Alder reaction. [25] As a result, the structure of diene monomers used for copolymerization was important to suppress Diels-Alder reaction, but the control of reactions was difficult by tuning other copolymerization conditions, such as temperature, concentration, initiators, and some additives for copolymerization. [25] In this study, we carried out radical copolymerization of PhMI, N-cyclohexylmaleimide (CHMI), N-n-butylmaleimide (BMI), and MAn in the combination with DMPD and 1,3-pentadiene (PD) as diene monomers (Figure 1), and investigated the structures and the thermal stability of the obtained copolymers.…”

“…Anhydride moiety and carbon‐to‐carbon double bond in the repeating unit of MAn/DMPD copolymer were available for several postpolymerization reactions; for example, crosslinking using epoxy compounds, alcohols, and amines as polyfunctional crosslinkers, and oxidative ozonolysis of carbon‐to‐carbon double bonds in the main chain, leading to polymer chain scission, decrosslinking of cured resins, and polymer surface modification ( Scheme ) . More recently, radical copolymerization of PhMI with several diene monomers was carried out under various reaction conditions as an attempt for the synthesis of high‐molecular‐weight copolymers by suppression of Diels–Alder reaction . As a result, the structure of diene monomers used for copolymerization was important to suppress Diels–Alder reaction, but the control of reactions was difficult by tuning other copolymerization conditions, such as temperature, concentration, initiators, and some additives for copolymerization …”

“…More recently, radical copolymerization of PhMI with several diene monomers was carried out under various reaction conditions as an attempt for the synthesis of high‐molecular‐weight copolymers by suppression of Diels–Alder reaction . As a result, the structure of diene monomers used for copolymerization was important to suppress Diels–Alder reaction, but the control of reactions was difficult by tuning other copolymerization conditions, such as temperature, concentration, initiators, and some additives for copolymerization …”