Polymerization of N‐(fluoro phenyl) maleimides

Abstract

Poly(N‐aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. These include N‐(2‐fluoro phenyl), N‐(3‐fluoro phenyl), N‐(4‐fluoro phenyl), N‐(2,4‐difluoro phenyl), N‐(2,5‐difluoro phenyl), N‐(2,3,5,6‐tetrafluoro phenyl), and N‐(pentafluoro phenyl). The polymerization of N‐(fluoro phenyl) maleimides by free‐radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ‐ray irradiation with that by free‐radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x‐ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free‐radical polymerization initiated by AIBN in bulk or in solution and by the self‐initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N‐(fluoro phenyl) maleimide]s have been analyzed by using a multiple‐heating‐rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. On the basis of the comparison between the overall activation energy of the thermal degradation of poly[N‐(fluoro phenyl) maleimide]s and NMR spectra of their corresponding monomers, it can be concluded that the 1H shifts due to ethylenic protons are so characteristic in sign and magnitude as to be useful in thermal stability elucidation. Some qualitative explanations were given on the stability of these polymers as affected by the type and size of the substituent. The x‐ray diffractograms of all samples show two rather broad peaks indicative of noncrystalline structures. The location of the peaks does not depend upon preparation conditions and temperature. Poly(N‐maleimide)s of fluoroanilines have not been hitherto described.

Synthesis of heat- and solvent-resistant polymers by radical polymerization of trifluoromethyl-substitutedN-phenylmaleimides

“…[13][14][15][16][17][18][19][20][21] For example, Barrales-Rienda et al 13,14 reported the polymerization of seven kinds of fluoro-substituted PhMIs, that is, 2-fluoro-, 3-fluoro-, 4-fluoro-, 2,4-difluoro-, 2,5-difluoro-, 2,3,5,6-tetra- radical and anionic polymerization of these maleimides in bulk or in solution as well as by g-ray irradiation polymerization. The structure and EXPERIMENTAL thermal degradation of the resulting polymers were examined in detail.…”

Synthesis and Radical Polymerization of N-(3-Acetyl-4-Carboxy-Phenyl)-Maleimide

“…These results allow us to associate the changes in x-ray spacing with either intermolecular (d i ) or intramolecular (d o ) vectors, depending on the location of the functional groups on the substituted aromatic ring [20].…”

Toughening of aromatic diamine‐cured trifunctional epoxy resins by modification with N‐phenylmaleimide–styrene copolymers containing pendant p‐hydroxyphenyl groups

“…It is well known that the radical copolymerization of PMI and St gives alternating copolymers. 28 The terpolymerization of PMI, APMI, and St must also afford alternating copolymers composed of both PMI-St and APMI-St units. HPMS was prepared by deacetylation of APMS ( Scheme 1 ) .…”