Control of thermal, mechanical, and optical properties of three‐component maleimide copolymers by steric bulkiness and hydrogen bonding

Abstract

N‐substituted maleimides polymerize in the presence of a radical initiator to give polymers with excellent thermal stabilities and transparency. In this study, we synthesized various maleimide copolymers with styrenes and acrylic monomers to control their thermal and mechanical properties by the introduction of bulky substituents and intermolecular hydrogen bonding. Three‐component copolymers of N‐(2‐ethylhexyl)maleimide in combination with styrene, α‐methylstyrene (MSt), or 1‐methylenebenzocyclopentane (BC5) as the styrene derivatives, and n‐butyl acrylate, 2‐hydroxyethyl acrylate, 4‐hydroxybutyl acrylate, or acrylic acid as the acrylic monomers were prepared by radical copolymerization. These copolymers were revealed to exhibit excellent heat resistance by thermogravimetric analysis. Glass transition temperatures increased by the introduction of bulky MSt and BC5 repeating units. The mechanical properties of the copolymer films were improved by the introduction of intermolecular hydrogen bonding. Optical properties, such as transmittance, refractive index, Abbe number, and birefringence, were determined for the copolymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1569–1579

Synthesis of Heat‐resistant Polymers by Thiol–Ene Reaction of N‐Allylmaleimide Copolymers Using Glycoluril Crosslinkers with Rigid Molecular Structures

“…The T g value increased in the range of 25–93 °C with an increase in the AMI content. The convenient control of both copolymer composition and T g value by random copolymerization of maleimides with acrylates is advantageous for the preparation of polymers with different properties. This was superior to the formation of copolymers with a specific composition under alternating and AAB sequence controls, as shown in the copolymerization with styrene and olefins .…”

“…We prepared random copolymers with different AMI contents ( P1 – P3 ) by radical copolymerization of AMI with 2‐ethylhexyl acrylate (2EHA), then the produced precursor polymers were thermally cured via a thiol–ene reaction in the presence of crosslinkers . In this study, 2EHA was selected as the comonomer, which provides random copolymers with a low T g . We used 1,3,4,6‐tetra(2‐mercaptoethyl)glycoluril ( G1 ), 1,3,4,6‐tetra(3‐mercaptopropyl)glycoluril ( G2 ), and 1,3,4,6‐tetraallylglycoluril ( G3 ) as the glycoluril crosslinkers as well as triallylisocyanurate (TAIC) and pentaerythritol tetrakis(3‐mercaptobutyrate) (PEMB) as the conventional crosslinkers, as shown in Figure .…”

“…4,5 Functional glycoluril derivatives are available as the crosslinkers for the construction of network polymer systems. [6][7][8] On the other hand, various compounds containing a reactive maleimide moiety are used for the syntheses of thermally stable copolymers with vinyl monomers by radical chain polymerization, [9][10][11][12][13][14][15][16][17][18] high-temperature polymer networks by successive addition reactions, [19][20][21][22][23][24][25] and degradable and stimuli-responsive network polymers by reversible Diels-Alder reactions. [26][27][28][29][30] We previously reported that Nallylmaleimide (AMI) copolymers produced by radical copolymerization were valid as the precursor polymers for thermoset systems with or without crosslinking agents.…”

“…36 copolymers with a low T g . [11][12][13] We used 1,3,4,6-tetra (2-mercaptoethyl)glycoluril (G1), 1,3,4,6-tetra(3-mercaptopropyl)glycoluril (G2), and 1,3,4,6-tetraallylglycoluril (G3) as the glycoluril crosslinkers as well as triallylisocyanurate (TAIC) and pentaerythritol tetrakis(3-mercaptobutyrate) (PEMB) as the conventional crosslinkers, as shown in Figure 1. IR spectroscopy, thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), a mechanical tensile test, and a single lapshear adhesion test were carried out in order to discuss the effects of the network structures on the heat-resistance and mechanical properties of the cured materials.…”

Thermal, Mechanical, and Optical Properties of Maleimide Copolymers Containing Twisted N‐Phenyl Substituents in the Side Chain

“…In addition, the degree of orientation was also difficult to be determined in this study. Therefore, the birefringence values at 50 % and 100 % draw ratios were compared, in which the experimental data for the other maleimide copolymers P3 and P4 (Scheme ) are also included . There was no clear difference among these maleimide copolymers (See also Table S2).…”