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1.
Yoshitomo Ono Naoyuki Kawashima Hiroto Kudo Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2005,43(19):4412-4421
The ring‐opening copolymerization of donor–acceptor norbornadiene (D–A NBD) dicarboxylic acid monoglycidyl ester derivatives with D–A NBD dicarboxylic acid anhydride was performed with tetraphenylphosphonium bromide as a catalyst in toluene to produce new norbornadiene (NBD) polyesters containing D–A NBD moieties in the main chain and in the side chain in one step in good yields. The photoisomerization of the D–A NBD moieties in these polyesters proceeded very smoothly to give the corresponding quadricyclane groups. Because these NBD polyesters contained many NBD moieties in the polymer chain, they had the highest capacity for heat storage in the D–A NBD polymers reported so far. The stored thermal energy of the irradiated polyesters was evaluated by differential scanning calorimetry analysis to be approximately 150–190 J/g. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4412–4421, 2005 相似文献
2.
Yousuke Konno Atsushi Kameyama Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2001,39(16):2683-2690
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 相似文献
3.
Synthesis and photochemical properties of poly(ester–amide)s containing norbornadiene (NBD) residues
Akihiko Ikeda Akinori Tsubata Atsushi Kameyama Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》1999,37(7):917-926
N,N′‐Bis[(3‐carboxynorbornadien‐2‐yl)carbonyl]‐N,N′‐diphenylethylenediamine (BNPE) was synthesized in 70% yield by the reaction of 2,5‐norbornadiene‐2,3‐dicarboxylic acid anhydride with N,N′‐diphenylethylenediamine. Other dicarboxylic acid derivatives containing norbornadiene (NBD) residues having N,N′‐disubstituted amide groups were also prepared by the reaction of 2,5‐NBD‐2,3‐dicarboxylic acid anhydride with certain secondary diamines. When the polyaddition of BNPE with bisphenol A diglycidyl ether (BPGE) was carried out using tetrabutylammonium bromide as a catalyst in N‐methyl‐2‐pyrrolidone at 100°C for 12 h, a polymer with number average molecular weight of 69,800 was obtained in 98% yield. Polyadditions of other NBD dicarboxylic acid derivatives containing N,N′‐disubstituted amide groups with BPGE were also performed under the same conditions. The reaction proceeded very smoothly to give the corresponding NBD poly(ester–amide)s in good yields. Photochemical reactions of the obtained polymers with N,N′‐disubstituted amide groups on the NBD residue were examined, and it was found that these polymers were effectively sensitized by adding appropriate photosensitizers such as 4‐(N,N‐dimethylamino)benzophenone and 4,4′‐bis(N,N‐diethylamino)benzophenone in the film state. The stored energies in the quadricyclane groups of the polymers were also evaluated to be about 94 kJ/mol by DSC measurement of the irradiated polymer films. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 917–926, 1999 相似文献
4.
Ahmed Oueslati Hatem Ben Romdhane Vincent Martin Fréderic Schiets Régis Mercier Refaât Chaâbouni 《Journal of polymer science. Part A, Polymer chemistry》2011,49(9):1988-1998
A novel pentamethylated norbornadiene (NBD) based dianhydride, α,α′‐bis‐(3,4,5,6,7‐pentamethylcyclopenta‐2,4‐dienyl)meta‐xylene‐1,2‐dianhydride (3), was prepared from α,α′‐bis‐(pentamethylcyclopentadienyl)meta‐xylene (1) and acetylene dicarboxylic acid. The bis‐adduct formed via Diels–Alder reaction afforded tetra‐acid (2), which was chemically cyclodehydrated to lead the targeted dianhydride (3). New polyimides containing NBD moieties in the main chain were prepared from the dianhydride monomer (3) and various aromatic diamines. The chemical structure of the polymers was confirmed by both 1H and 13C NMR analysis. Their Molecular weights were also measured by SEC. All of these polyimides are soluble at room temperature in common organic solvents, such as chloroform, dichloromethane, THF, DMSO, DMF, and NMP, and show good thermal stabilities. The photochemical isomerization of the NBD into quadricyclane (QC) was investigated by UV/vis spectrophotometry from polymer films using visible sunlight as irradiation source. It was found that the kinetic rate of the conversion NBD‐QC which proceeded smoothly is a first kinetic order. The stored energies released by the transformation of QC groups into NBD ones of the irradiated polymer films were also evaluated by DSC measurement and were found to be around 90 kJ mol?1. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
5.
Ahmed Oueslati Imen Abdelhedi Régis Mercier Eric Drockenmuller Hatem Ben Romdhane 《Journal of polymer science. Part A, Polymer chemistry》2013,51(21):4650-4656
Photoresponsive polyamides containing main‐chain pentamethylated norbornadiene (NBD) moieties are obtained in quantitative yields via the Yamazaki–Higashi reaction between a pentamethylated NBD dicarboxylic acid and a series of aromatic diamines. Chemical structures are confirmed by 1H and 13C NMR and weight average molar masses measured by SEC are in the range of 21,500–28,600 g mol?1 with chain dispersities close to 2. Physical properties are investigated by FTIR, differential scanning calorimetry (DSC), thermogravimetric analysis, and viscosimetry. All obtained polyamides are amorphous with glass transition temperatures ranging from 68 to 124 °C. They are soluble at room temperature in common organic solvents and exhibit good thermal stabilities with Td10 values ranging from 175 to 276 °C. The photochemical isomerization of the NBD moiety into quadricyclane (QC) is studied by UV/vis spectroscopy after sunlight irradiation of polymer films. For all polyamides, a first‐order kinetic rate is observed for the conversion of NBD to QC. The thermal release of the stored energy associated to the reverse transformation of QC groups into NBD ones is about 90–95 kJ mol?1 as measured by DSC of the irradiated polymer films. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4650–4656 相似文献
6.
Naoyuki Kawashima Atsushi Kameyama Tadatomi Nishikubo Takabumi Nagai 《Journal of polymer science. Part A, Polymer chemistry》2001,39(10):1764-1773
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 相似文献
7.
Takashi Iizawa Tomoko Sueyoshi Chikara Hijikata Tadatomi Nishikubo 《Journal of polymer science. Part A, Polymer chemistry》1994,32(16):3091-3098
Polymers having pendant norbornadiene (NBD) moieties and rigid main chain were prepared from the reaction of partially brominated poly(2,6-dimethyl-p-phenylene oxide) with a potassium carboxylate derivative of the corresponding NBD using a phase transfer catalyst in chlorobenzene. The photochemical valence isomerization of pendant NBD to quadricyclane (QC) moieties proceeded smoothly in the film state as well as polymer solution upon the irradiation by sunlight, xenon lamp, or high-pressure mercury lamp. The rate of isomerization was affected by the structure of main chain in the polymer and the substituent groups of NBD derivatives. The catalytic reversion of the resulting QC moiety to the original NBD proceeded smoothly in the solution with (5,10,15,20-tetraphenyl-21H,23H-por-phine)cobalt(II) as the catalyst at room temperature; however, the reaction of NBD polymer containing poly(2,6-dimethyl-p-phenylene oxide) (PPO) showed lower reactivity than that of the corresponding low molecular weight QC compound. When the cycle between the photochemical valence isomerization of NBD moiety to quadricyclane (QC) moiety and thermal reversion of QC moiety to NBD moiety at 160°C was repeated, the NBD polymer synthesized from PPO degraded gradually, whereas NBD polymer prepared from poly(4-chloromethylstyrene) decomposed easily. Therefore, the rigid PPO structure showed high resistance for the degradation of NBD moiety. © 1994 John Wiley & Sons, Inc. 相似文献
8.
Satoko Ishibe Ikuyoshi Tomita 《Journal of polymer science. Part A, Polymer chemistry》2005,43(15):3403-3410
A novel synthetic method for soluble precursor polymers of poly(p‐phenylene vinylene) (PPV) derivatives by the palladium‐catalyzed three‐component coupling polycondensation of aromatic diiodides, aromatic bis(boronic acid) derivatives, and norbornadiene is described. For example, the polymerization of 1,4‐diiodo‐2,5‐dioctyloxybenzene, benzene‐1,4‐bis(boronic acid propanediol ester), and norbornadiene at 100 °C for 3 days provided a polymer consisting of the three monomer units in a 97% yield (number‐average molecular weight = 3100, weight‐average molecular weight/number‐average molecular weight = 1.37). A derivative of PPV was produced smoothly by the retro Diels–Alder reaction of the polymer both in a dodecyloxybenzene solution and in a film at 200 °C in vacuo. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3403–3410, 2005 相似文献
9.
Imen Abdelhedi Miladi Bhanu Prakash Mudraboyina Ahmed Oueslati Eric Drockenmuller Hatem Ben Romdhane 《Journal of polymer science. Part A, Polymer chemistry》2014,52(2):223-231
Polyesters and polyethers containing norbornadiene (NBD) and 1,2,3‐triazole units in the main chain are prepared by step growth polymerization of diester or diether NBD‐based dialkynes with different aromatic diazides using copper‐catalyzed azide–alkyne cycloaddition. The solubility and the physical properties of the resulting polytriazoles are investigated by differential scanning calorimetry, thermogravimetric analysis, size exclusion chromatography, and 1H NMR spectroscopy, and are discussed taking into account of the chemical structures of the monomers. All of them are amorphous with glass transition temperatures ranging from 51 to 117 °C, number average molecular weight (Mn) values from 16 to 43 kDa and thermal degradation (Td10) values from 175 to 292 °C. The photochemical valence isomerization (PVI) of the NBD units into quadricyclanes (QC) is investigated using UV–vis spectroscopy of polymer films spin‐coated onto quartz substrates. For the first time the PVI of NBD into QC is demonstrated by 1H NMR spectroscopy. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 223–231 相似文献
10.
Masashi Shiotsuki Hironobu Kai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2014,52(17):2528-2536
New 2,5‐norbornadiene‐type monomers bearing 1‐adamantyl and cyclohexyl ester groups on their 2‐position polymerized with azobisisobutyronitrile to form the polymers consisting of two types of polymer unit structures. The major part had a saturated nortricyclene framework, which was formed by 2,6‐addition along with intramolecular cyclization on the norbornadiene moiety. The minor part consisted of 2‐norbornene‐type units constructed via 2,3‐addition. A series of norbornadiene‐based monomers spontaneously polymerized in the presence of oxygen. Because a radical inhibitor, namely hydroquinone, could suppress this spontaneous reaction, it was indicated that the oxygen‐induced polymerization proceeds via free‐radical polymerization mechanism. Changing a quantity of provided oxygen gas (O2) to a norbornadiene monomer significantly affected on polymerization results, in specific, molecular weight of the formed polymer, which indicated that oxygen serves as one of the key reagents for the formation of free‐radical initiating species. It was proven that the combination of norbornadiene ethyl ester with O2 was applicable as a new free‐radical initiator for polymerization of methyl methacrylate. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2528–2536 相似文献
11.
Tadatomi Nishikubo Atsushi Kameyama Katsuhiko Kishi Yasushi Mochizuki 《Journal of polymer science. Part A, Polymer chemistry》1994,32(14):2765-2773
New photoresponsive polymers 1–4 containing pendant norbornadiene (NBD) moieties with N,N-disubstituted amide groups were synthesized with 97, 98, 92, and 94% conversions by the substitution reaction of poly (p-chloromethyl) styrene] with potassium salts of 3piperidyloxo-2,5-NBD-2-carboxylic acid, 3-(NN-dipropylcarbamoyl) -2,5-NBD-2-carboxylic acid, 3-(N-methyl-N-phenylcarbamoyl)-2,5-NBD-2-carboxylic acid, and 3-(N,N-dipheylcarbmoyl)-2,5-NBD-2-carboxylic acid, respectively, using tetrabutylammonium bromide as a phase transfer catalyst for all. Polymers 1–4 with N,N-disubstituted amide groups on the NBD moieties were sensitized by adding appropriate photosensitizers such as Michler's ketone and 4- (N,N-dimethylamino) benzophenone in the film state, although the reactivities of the polymers without photosensitizer were lower than that of our previously reported polymer 5 containing pendant 3- (N-phenylcarbamoyl) -2,5-NBD-2-carboxylate moiety. It was also found that the photo-irradiated retaining polymers 1–4 containing the corresponding QC moieties can be stored about 80–86 kJ/mol of their thermal energy. © 1994 John Wiley & Sons, Inc. 相似文献
12.
Tadatomi Nishikubo Tatsuo Kawashima Sadayuki Watanabe 《Journal of polymer science. Part A, Polymer chemistry》1993,31(7):1659-1665
Polymers bearing photoresponsive norbornadiene (NBD) moieties were synthesized by the addition reaction of poly(glycidyl methacrylate-co-methyl methacrylate)s containing pendant epoxide groups with 3-phenyl-2,5-norbornadiene-2-carboxylic acid (PNBC), 3-[(phenyl)carbamoyl]-2,5-norbornadiene-2-carboxylic acid 3-[(4-acetylphenyl) carbamoyl]-2,5-norbornadiene-2-carboxylic acid (APCND), and 3-[(4-methoxyphenyl)carbamoyl]-2,5-norbornadiene-2-carboxylic acid using tetrabutylammonium bromide as a catalyst in DMF. The polymers bearing pendant PNBC or APCND moieties have higher photochemical reactivity in the film state than the polymers bearing pendant PCND or MPCND moieties. Although the pendant quadricyclane (QC) group produced by the photoirradiation of the PNBC moiety in these polymers has excellent storage stability in the film state, without catalyst at room temperature, the QC group in the polymer film with the catalyst reverts gradually to the NBD moiety at room temperature. © 1993 John Wiley & Sons, Inc. 相似文献
13.
Patrick Lorenz Prof. Dr. Andreas Hirsch 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(23):5220-5230
The synthesis and properties of various norbornadiene/quadricyclane (NBD/QC) fullerene hybrids are reported. By cyclopropanation of C60 with malonates carrying the NBD scaffold a small library of NBD–fullerene monoadducts and NBD–fullerene hexakisadducts was established. The substitution pattern of the NBD scaffold, as well as the electron affinity of the fullerene core within these hybrid systems, has a pronounced impact on the properties of the corresponding energy rich QC derivatives. Based on this, the first direct photoisomerization of NBD–fullerene hybrids to their QC derivatives was achieved. Furthermore, it was possible to use the redox-active fullerene core of a QC–fullerene monoadduct to enable the back reaction to form the corresponding NBD–fullerene monoadduct. Combining these two processes enables switching between NBD and QC simply by changing the irradiation wavelength between 310 and 400 nm. Therefore, turning this usually photo/thermal switch into a pure photoswitch. This not only simplifies the investigation of the underlying processes of the NBD–QC interconversion within the system, but also renders such hybrids interesting for applications as molecular switches. 相似文献
14.
Tadatomi Nishikubo Atsushi Kameyama Chinatsu Izawa 《Journal of polymer science. Part A, Polymer chemistry》2001,39(3):368-375
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 (Mn) 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 (Mn = 28,700) and polymer 3 (Mn = 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 相似文献
15.
Tadatomi Nishikubo Chikara Hijikata Takashi Iizawa 《Journal of polymer science. Part A, Polymer chemistry》1991,29(5):671-676
A polymer bearing pendant norbornadiene (NBD) moieties and a low molecular weight model compound ([2-carbobenzyloxy-3-phenyl-2,5-norbornadiene CBPNB)], were synthesized by substitution reaction of poly(p-chloromethylstyrene) and benzyl chloride, respectively, with the potassium salt of 3-phenyl-2,5-norbornadiene-2-carboxylic acid. Photochemical valence isomerization and storage stabilities of the resulting polymer having corresponding pendant quadricyclane (QC) groups and the low molecular weight QC compound were investigated in dichloromethane solution. It was found that the rate of photochemical valence isomerization of the pendant NBD moiety in the polymer was the same as or slightly higher than that of CBPNB, and the storage stability of the QC group in the polymer was higher than that of the QC compound resulting from CBPNB in the solution. The photochemical reaction of the pendant NBD moiety within the polymer without catalyst proceeded quantitatively in the film state. However, the photochemical reaction of the polymer films blended with 5,10,15,20-tetraphenyl-21H,23H-porphine cobalt (II) catalyst (Co-TPP) did not proceed quantitatively, and the degree of conversion of the pendant NBD moiety in the polymer decreased with increasing amounts of Co-TPP in the film. The QC group produced in the polymer by photo-irradiation had excellent storage stability in the film state without Co-TPP. On the other hand, the QC group in the polymer films blended with Co-TPP Catalyst reverted gradually to the NBD group at room temperature. 相似文献
16.
Lei Han Dr. Hengxing Wei Shayu Li Dr. Jinping Chen Dr. Yi Zeng Dr. Ying‐Ying Li Dr. Yongbin Han Dr. Yi Li Prof. Dr. Shuangqing Wang Dr. Guoqiang Yang Prof. Dr. 《Chemphyschem》2010,11(1):229-235
A supramolecular dyad, BP‐(amidinium‐carboxylate)‐NBD is constructed, in which benzophenone (BP) and norbornadiene (NBD) are connected via an amidinium‐carboxylate salt bridge. The photophysical and photochemical properties of the assembled BP‐(amidinium‐carboxylate)‐NBD dyad are examined. The phosphorescence of the BP chromophore is efficiently quenched by the NBD group in BP‐(amidinium‐carboxylate)‐NBD via the salt bridge. Time‐resolved spectroscopy measurements indicate that the lifetime of the BP triplet state in BP‐(amidinium‐carboxylate)‐NBD is shortened due to the quenching by the NBD group. Selective excitation of the BP chromophore results in isomerization of the NBD group to quadricyclane (QC). All of these observations suggest that the triplet–triplet energy transfer occurs efficiently in the BP‐(amidinium‐carboxylate)‐NBD salt bridge system. The triplet–triplet energy transfer process proceeds with efficiencies of approximately 0.87, 0.98 and the rate constants 1.8×103 s?1, and 1.3×107 s?1 at 77 K and room temperature, respectively. The mechanism for the triplet–triplet energy transfer is proposed to proceed via a “through‐bond” electron exchange process, and the non‐covalent bonds amidinium‐carboxylate salt bridge can mediate the triplet–triplet energy transfer process effectively for photochemical conversion. 相似文献
17.
Nermina Leber Jonathan D. B. Fay Neil R. Cameron Peter Krajnc 《Journal of polymer science. Part A, Polymer chemistry》2007,45(17):4043-4053
A series of monolithic crosslinked polymers with 2,4,6‐trichlorophenyl acrylate as a reactive component was prepared by free radical polymerization of the internal phases of high internal phase emulsions (HIPEs). The volume ratio of water to oil phase (void volume; 60–90%), crosslinker type (divinylbenzene or ethylenglycol dimethacrylate) and quantity (30–50 mol %) and type of porogenic solvent (chlorobenzene, toluene, chloroform, dichloroethane) were altered to study these effects on the structure and reactivity of the monolithic polymers. The polymer supports were characterized by scanning electron microscopy (SEM), FTIR spectroscopy, elemental analysis and mercury intrusion porosimetry. SEM images revealed an open cellular structure with voids between 1 and 12 μm and window sizes between 0.3 and 3 μm. The porogen had an influence on the surface area, being larger with added porogen and the influence being highest with toluene. Adding toluene also influenced the void size, increasing the average diameter from ~2 μm (no porogen) to ~12 μm (added toluene). Monolithic supports were functionalized by reaction of the ester moieties with tris(2‐aminoethyl)amine derivative and by hydrolysis of the ester groups to carboxylic acids. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4043–4053, 2007 相似文献
18.
Ming Jin Ran Lu Qing Xin Yang Chun Yan Bao Ren Sheng Ting Hua Xu YingYing Zhao 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3460-3472
The preparation of a series of novel homopolymers and copolymers containing bisazobenzene chromophores with side‐on structure in the side chains via atom transfer radical polymerization (ATRP) were presented. UV–vis spectra of the thin films of these polymers under irradiation of 488 nm Ar+ laser suggested that the photoisomerization of the bisazobenzene chromophores happened mainly on one of the two azo groups in the bisazobenzene chromophores with similar probability due to their side‐on structure. Good photoalignment behaviors of these polymers were proved by photoinduced birefringence measurements because side‐on structure permitted the two azo groups in the bisazobenzene chromophores both participated in the trans–cis–trans photoisomerization cycles equally to induce the whole chromophore reorientation. Furthermore, the reorientation axis located at the middle of chromophore decreased the sweep volume during photoalignment. The impetus for this study was to evaluate the photoisomerization and photoalignment process of side‐on bisazobenzene‐containing polymers and to find possible applications in the photosensitive devices. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3460–3472, 2007 相似文献
19.
Hirofumi Kuroda Ikuyoshi Tomita Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》1997,35(4):787-793
The hydrolysis and the substitution reaction of the main chain of the polymer having β-alkoxyenoate moieties in the main chain are described. The hydrolysis of the polymer prepared from 2,2-dimetylpropylene-1,3-bis(propiolate) and p-xylene glycol under acidic conditions proceeded smoothly to obtain diols in quantitative yield by the cleavage of both ester and vinyl ether moieties. On the other hand, carboxylic acids were obtained by the hydrolysis of the polymer under alkaline conditions. The aminolysis with pyrrolidine gave the β-aminoenoate by the selective fission of vinyl ether moieties in quantitative yield. Furthermore, a polymer having β-aminoenoate moieties in the main chain was obtained by the reaction with piperazine via the displacement of the main chain. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 787–793, 1997 相似文献
20.
Xinde Tang Longcheng Gao Nianfeng Han Xinghe Fan Qifeng Zhou 《Journal of polymer science. Part A, Polymer chemistry》2007,45(15):3342-3348
4‐Arm star side‐chain liquid crystalline (LC) polymers containing azobenzene with different terminal substituents were synthesized by atom transfer radical polymerization (ATRP). Tetrafunctional initiator prepared by the esterification between pentaerythritol and 2‐bromoisobutyryl bromide was utilized to initiate the polymerization of 6‐[4‐(4‐methoxyphenylazo)phenoxy]hexyl methacrylate (MMAzo) and 6‐[4‐(4‐ethoxyphenylazo)phenoxy]hexyl methacrylate (EMAzo), respectively. The 4‐arm star side‐chain LC polymer with p‐methoxyazobenzene moieties exhibits a smectic and a nematic phase, while that with p‐ethoxyazobenzene moieties shows only a nematic phase, which derives of different terminal substituents. The star polymers have similar LC behavior to the corresponding linear homopolymers, whereas transition temperatures decrease slightly. Both star polymers show photoresponsive isomerization under the irradiation with UV–vis light. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3342–3348, 2007 相似文献