Synthesis and photochemical property of polymers with pendant donor–acceptor-type norbornadiene moieties

The donor–acceptor-type norbornadiene (D–A NBD) 1,4,5,6-tetramethyl-3-phenyl-2,5-NBD-2-carboxylic acid was prepared by the Diels–Alder reaction of methyl 3-phenylprop-2-ynoate with 1,2,3,4-tetramethyl-1,3-cyclopentadiene. 1,4,5,6,7-Pentamethyl-3-phenyl-2,5-NBD-2-carboxylic acid was also synthesized in the same way. Styrene-type polymers with pendant D–A NBD moieties were prepared with a 100% degree of substitution (DS) by the reaction of D–A NBD carboxylic acids with poly[(p-chloromethyl)styrene] with 1,8-diazabicyclo[5.4.0]undecene-7 in dimethyl sulfoxide at 70 °C for 6 h. In the reaction of D–A NBD carboxylic acids with poly(2-chloroethyl vinyl ether), the DSs were about 60%. The photochemical valence isomerizations of all the NBD polymers proceeded smoothly with UV irradiation in tetrahydrofuran solutions and in the film state. In addition, the rate of the photochemical reaction of the NBD polymers increased efficiently by the addition of 4,4′-bis(diethylamino)benzophenone as a photosensitizer in a film state. The stored thermal energy of the irradiated polymers was also evaluated by differential scanning calorimetry to be 55–74 kJ/mol. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1764–1773, 2001     

Synthesis of new photoresponsive polyesters containing norbornadiene residues by the polyaddition of donor–acceptor norbornadiene dicarboxylic acid diglycidyl ester with dicarboxylic acids and their photochemical properties

A donor–acceptor norbornadiene derivative, 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid diglycidyl ester (D–A NDGE), was synthesized by the reaction of the cesium salt of 5‐(4‐methoxyphenyl)‐1,4,6,7,7‐pentamethyl‐2,5‐norbornadiene‐2,3‐dicarboxylic acid with epibromohydrin in N‐methyl‐ pyrrolidone (NMP). The polyaddition reactions of D–A NDGE with certain dicarboxylic acids were carried out with tetrabutylammonium bromide as a catalyst in NMP, producing corresponding polyesters containing D–A norbornadiene (NBD) residues in the main chain in fair to good yields. The photoisomerization of the D–A NBD residues in the polyesters proceeded very smoothly, forming the corresponding quadricyclane groups. The photoreactivities of the D–A NBD residues in the polymer were 50 times higher than those of the NBD residues in the film state and 60 times higher than those in a tetrahydrofuran solution. The stored energy in the quadricyclane groups of the polymers was about 45–55 kJ/mol according to differential scanning calorimetry analysis of the irradiated polymer films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2683–2690, 2001     

Synthesis of hetero‐telechelic polymers by self‐polyaddition of monomers containing both oxetanyl and carboxyl groups

The synthesis and self‐polyaddition of new monomers, o‐, m‐, and p‐[(3‐ethyloxetane‐3‐yl)methoxyethyl]benzoic acid (o‐EOMB, m‐EOMB, and p‐EOMB) containing both oxetanyl groups and carboxyl groups were examined. The reactions of o‐EOMB, m‐EOMB, and p‐EOMB in the presence of tetraphenylphosphonium bromide as a catalyst in o‐dichlorobenzene at 150–170 °C resulted in self‐polyaddition to give the corresponding hetero‐telechelic polymers poly(o‐EOMB), poly(m‐EOMB), and poly(p‐EOMB) with M_ns = 14,500–33,400 in satisfactory yields. The M_n of poly(o‐EOMB) decreased at higher reaction temperatures than 150 °C, unlike those of poly(m‐EOMB) and poly(p‐EOMB), possibly due to inter‐ or intraester exchange side reactions. It was also found that the thermal properties and solubilities of these polymers were supposed with the proposed structures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7835–7842, 2008     

Syntheses and properties of hyperbranched polybenzoxazole by thermal cyclodehydration of hyperbranched poly[o‐(t‐butoxycarbonyl)amide] via A2 + B3 approach

The syntheses and properties of hyperbranched poly(o‐hydroxyamide) [poly(HAB‐BCC)‐ABP], poly[o‐(t‐butoxycarbonyl)amide] [poly(HAB‐BCC)‐ABP‐t‐BOC], and polybenzoxazole [poly(HAB‐cycloBCC)] were examined. Poly(HAB‐BCC)‐ABP was obtained from the polycondensation reaction of 3,3‐dihydroxy‐4,4′‐diaminobiphenyl (HAB) as an A₂‐monomer and 1,3,5‐benzenetricarboxylchloride (BCC) as a B₃‐monomer with 2‐amino‐4‐t‐butylphenol (ABP) in NMP in the presence of pyridine for 24 h. The reaction of poly(HAB‐BCC)‐ABP and di‐t‐buthylcarbonate (DiBOC) was performed to obtain the corresponding poly(HAB‐BCC)‐ABP‐t‐BOC with pendant t‐BOC groups. The thermal cyclodehydration of poly(HAB‐BCC)‐ABP‐t‐BOC was carried out in the film sate at 400 °C, affording the poly(HAB‐cyclo‐BCC) in quantitative yield. Furthermore, the solubilities and thermal properties of these polymers were examined. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3640–3649, 2006     

Synthesis of polyesters with pendant oxetane groups by the chemoselective alternating copolymerization of 3‐ethyl‐3‐(glycidyloxymethyl)oxetane with carboxylic anhydride and its photochemical reaction

The synthesis of polyesters with pendant oxetane groups by the chemoselective alternating copolymerization of 3‐ethyl‐3‐(glycidyloxymethyl)oxetane (EGMO) with carboxylic anhydride and the photochemical reaction of the resulting polymer was examined. The alternating copolymerization of EGMO with phthalic anhydride proceeded chemoselectively with quaternary onium salts under appropriate reaction conditions, and the corresponding soluble polymers with pendant oxetane groups with number‐average molecular weights of 4700–7200 were obtained in 72–87% yields. Furthermore, the photochemical reaction of the resulting polymers was examined with certain photoacid generators in the film state upon UV irradiation, and it was found that the photocrosslinking reaction of the pendant oxetane groups proceeded smoothly to give the insoluble polymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1952–1961, 2003     

Synthesis of polyester by novel addition reaction of active di-ester with di-epoxy compound

Some polyesters having pendant ether groups were synthesized with high yield by polyaddition of active di-esters such as di(S-phenyl)thioisophthalate (PTIP) and di(S-phenyl)thiosebacate with di-epoxy compounds such as diglycidyl ether of bisphenol A (BPGE) and diglycidyl ether of ethylene glycol using some quaternary ammonium salts as a catalyst. The degree of polymerization in the reaction of PTIP with BPGE was strongly affected by the kind of reaction solvent, monomer concentration, the reaction temperature, and the kind of catalyst. As a result, it is found that tetrabutylammonium chloride has the highest catalytic activity for the polyaddition of PTIP with BPGE, and dimethylsulfoxide is a suitable solvent for the reaction system.     

Synthesis of polyethers with unsymmetrical structures by the polyaddition of 3‐ethyl‐3‐(glycidyloxymethyl)oxetane with diacyl chlorides

Polyethers with unsymmetrical structures in the main chains and pendant chloromethyl groups were synthesized by the polyaddition of 3‐ethyl‐3‐(glycidyloxymethyl)oxetane (EGMO) with certain diacyl chlorides with quaternary onium salts or pyridine as catalysts. The unsymmetrical polyaddition of EGMO containing two different cyclic ether moieties such as oxirane and oxetane groups with terephthaloyl chloride proceeded smoothly in toluene at 90 °C for 6 h to give polymer 1 with a number‐average molecular weight (M_n) of 51,700 in a 93% yield when tetrabutylammonium bromide (TBAB) was used as a catalyst. The polyaddition also proceeded smoothly under the same conditions when other quaternary onium salts, such as tetrabutylammonium chloride, tetrabutylammonium iodide, tetrabutylphosphonium chloride, and tetrabutylphosphonium bromide, and pyridine were used as catalysts. However, without a catalyst no reaction occurred under the same reaction conditions. Polyadditions of EGMO with isophthaloyl chloride and adipoyl chloride gave polymer 2 (M_n = 28,700) and polymer 3 (M_n = 25,400) in 99 and 65% yields, respectively, under the same conditions. The chemical modification of the resulting polymer, polymer 1 , which contained reactive pendant chloromethyl groups, was also attempted with potassium 3‐phenyl‐2,5‐norbornadiene‐2‐carboxylate with TBAB as a phase‐transfer catalyst, and a polymer with 65 mol % pendant norbornadiene moieties was obtained. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 368–375, 2001     

Synthesis and photochemical reaction of novel p-alkylcalix[6]arene derivatives containing acryloyl or methacryloyl groups

Novel polyfunctional (meth)acrylates with a calixarene backbone [calixarene (meth)acrylates] were synthesized in good yields by certain reactions of p-methylcalix[6]arene (1a) or p-tert-butylcalix[6]arene (1b) with (meth)acrylate derivatives such as acryloyl chloride, methacryloyl chloride, (2-methacryloxy)ethyl isocyanate, and glycidyl methacrylate. Polyfunctional acrylate 6a having poly(oxyethylene) spacer chain between 1a and acrylate groups was also synthesized by the reaction of the poly(oxyethylene) modified 1a with acrylic acid. Calixarene acrylate 6a was liquid at room temperature, although the other calixarene (meth)acrylates were solid at room temperature. The initial decomposition temperature (IDT) of the resulting calixarene (meth)acrylates was measured by the thermogravimetric analysis to evaluate the thermal stability, and it was found that some of the IDTs of the calixarene acrylates were over 400°C. This means that calixarene (meth)acrylates have very good thermal stability. The photopolymerization of the resulting some calixarene (meth)acrylates with (2-phenyoxy)ethyl acrylate as a reactive diluent in the presence of photoinitiator proceeded smoothly upon irradiation with UV light. Therefore, polyfunctional (meth)acrylates with a calixarene backbone can be expected to be novel and thermally stable photoreactive acrylate oligomers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3071–3078, 1999     

Novel synthesis of polyphosphonates by the polyaddition of bis(epoxide) with diaryl phosphonates

The polyaddition of bisphenol A diglycidyl ether (BPGE) with bis(4‐chlorophenyl) phenylphosphonate was carried out using quaternary onium salts or crown ether complexes as catalysts. When the polyaddition was performed using tetrabutylammonium chloride, tetrabutylphosphonium chloride, or 18‐crown‐6/KCl in N‐ methyl‐2‐pyrrolidone at 110°C for 48 h, the corresponding polyphosphonate with moderated molecular weights was obtained in 88–96% yields. The structure of the resulting polyphosphonate was confirmed by IR and ¹H‐NMR spectra. The polyaddition of BPGE with various diaryl phosphonates also proceeded very smoothly to produce the corresponding polyphosphonates with moderate molecular weights. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 959–965, 1999