Synthesis of Polyesters Carrying Norbornadiene (NBD) Moieties by the Ring-Opening Copolymerization of Glycidyl Esters Containing NBD Moieties with Carboxylic Anhydrides and Their Photochemical Reactions

Abstract

Various epoxy monomers containing norbornadiene (NBD) moieties were prepared by reactions of potassium salts of NBD derivatives with excess epichlorohydrin using tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. The copolymerization of glycidyl (3-phenyl-2,5-norbornadien-2-yl)carboxylate (GPNC) with phthalic anhydride (PAn) proceeded smoothly using TBAB as a catalyst in sulfolane at 100 °C for 24 h to give polyester P-1 containing pendant NBD moieties. Copolymerizations of various epoxy monomers containing certain NBD moieties with carboxylic anhydrides gave the corresponding NBD polyesters in good yields. The photochemical valence isomerizations of the NBD moieties in the polymers were carried out in the film state or in the solution. Rates of the isomerizations of some NBD moieties in the polymers were strongly enhanced by the addition of photosensitizers such as 4-(N,N-dimethylamino)benzophenone (DABP). The T gs of the polyesters having NBD residues and stored thermal energy in the corresponding quadricyclane (QC) groups in the polymers were measured by DSC analysis. The T gs of the NBD polymers were 45−93 °C. Polyesters having QC groups after photoirradiation released their stored thermal energies (about 90 kJ/mol) at temperatures above the T gs of the corresponding NBD polymers.

Photoresponsive polyamides containing pentamethylated norbornadiene moieties: Synthesis and photochemical properties under sunlight irradiation

“…These consecutive irradiation/thermal release processes could be repeated several times without modifying both T g and content of energy released, which confirm the reproducibility of the process. Similar values ranging from 91 to 95 kJ mol −1 were obtained for polyamides 7–12 , which are in good accordance with those reported earlier for other NBD‐containing polymer materials …”

“…In addition to conversion and storage of solar energy, the photochemical isomerization of NBD has been studied as a new alternative in the field of optoelectronics (memory, optical switches and other devices), as a photochromic system with potential application in the data storage technology, and as an energetic binder for solid rocket propellants . NBD structures are generally introduced into polymer chains as pendant moieties by postpolymerization chemical modification, by radical or cationic polymerizations of NBD‐containing vinyl monomers, or by ring‐opening copolymerization of glycidyl esters containing NBD moieties with various carboxylic anhydrides . Besides, the synthesis of polyamides containing NBD structure in the backbone by direct or catalyst transfer polycondensation has been reported earlier …”

Synthesis of Self-Photosensitizing Polyesters Carrying Pendant Norbornadiene (NBD) Moieties and Benzophenone Groups and Their Photochemical Reactions

“…For the reference of the photochemical reaction, ring-opening copolymerizations of epoxy monomers containing NBD moieties with PAn were carried out under the same conditions, and polyesters P-a, P-b, and P-c containing corresponding NBD moieties were obtained. 17 M n 's of these polymers were 13 000-19 000. M n 's of polyesters P-1-P-9 containing pendant BP groups were lower than those of polyesters P-a-P-c having no pendant BP group.…”

Synthesis and photochemical properties of novel pentamethylated norbornadiene containing polyimides

“…The introduction of NBD groups into the polymer chains as a side groups were performed either by chemical polymer modification,14–18 by cationic polymerization of NBD containing vinylic monomers,19 or by ring‐opening copolymerization of glycidyl esters containing NBD moieties with carboxylic anhydrides 20…”