Synthesis and characterization of novel photopolymerizable multifunctional 2-propenyl ether analogues

Monomers bearing two, three, four, and six cationically polymerizable aryl 2-propenyl groups were synthesized and characterized. These compounds can be readily prepared by the catalytic isomerization of the corresponding allyl compounds. Strong bases and tris(triphenylphosphine)ruthenium(II) dichloride were used as the catalysts for these isomerizations. A study of the cationic photopolymerizations of these novel monomers was carried out using a diaryliodonium salt photoinitiator. The polymerization involves a stepwise condensation of the monomers followed by an intramolecular ring closure to form polyindanes. The resulting photopolymerized polymers underwent thermal oxidative decomposition at temperatures over 430°C. © 1993 John Wiley & Sons, Inc.     

A bicyclic conjugated diene monomer,tetrahydroindene, for cationic polymerization and a novel alicyclic hydrocarbon polymer with heat resistance

This study was directed toward the cationic polymerization of tetrahydroindene (i.e., bicyclo[4.3.0]‐2,9‐nonadiene), a bicyclic conjugated diene monomer, with a series of Lewis acids, especially focusing on the synthesis of high‐molecular‐weight polymers and subsequent hydrogenation for novel cycloolefin polymers with high service temperatures. EtAlCl₂ or SnCl₄ induced an efficient and quantitative cationic polymerization of tetrahydroindene to afford polymers with relatively high molecular weights (number‐average molecular weight > 20,000) and 1,4‐enchainment bicyclic main‐chain structures. The subsequent hydrogenation of the obtained poly(tetrahydroindene) with p‐toluenesulfonyl hydrazide resulted in a saturated alicyclic hydrocarbon polymer with a relatively high glass transition (glass‐transition temperature = 220 °C) and improved pyrolysis temperature (10% weight loss at 480 °C). The new diene monomer was randomly copolymerized with cyclopentadiene at various feed ratios in the presence of EtAlCl₂ to give novel cycloolefin copolymers, which were subsequently hydrogenated into alicyclic copolymers with variable glass‐transition temperatures (70–220 °C). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6214–6225, 2006     

Polycarbazoles via C?N coupling reactions of phthaloyl bis‐9H‐carbazoles with activated difluorides

1,3‐Phthaloyl bis‐9H‐carbazole (MPC) and 1,4‐phthaloyl bis‐9H‐carbazole (PPC) were synthesized by a Friedel‐Crafts reaction of carbazole with terephthaloyl chloride or isophthaloyl chloride. Homopolymers were obtained by a C? N coupling reaction with activated difluorides and copolymers were synthesized with 4,4′‐biphenol as a comonomer by a nucleophilic substitution reaction between these NH‐ and OH‐containing monomers and the activated difluoro monomers. The inherent viscosities of the polymers ranged from 0.35 to 1.03 dL/g. These polymers exhibited glass‐transition temperatures greater than 238 °C with the PPC‐containing homopolymer showing the highest value, 326.4 °C. The thermal stabilities indicated no significant weight loss below 450 °C and the temperatures of 5% weight loss ranged from 514.0 to 546.3 °C. The polymers showed reasonable solubility in organic solvents such as DMAC, DMSO, and NMP. UV absorption and fluorescence emission properties are presented. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4326–4331, 2009     

Development of hydrogenated ring‐opening metathesis polymers

New hydrogenated ring‐opening metathesis polymers with excellent thermal and optical properties were developed. These polymers were prepared by the ring‐opening metathesis polymerization of ester‐substituted tetracyclododecene monomers followed by the hydrogenation of the main‐chain double bond. The degree of hydrogenation was an important factor for the thermal stability of the polymers, and as complete hydrogenation as possible was necessary to obtain a thermally stable polymer. The completely hydrogenated ring‐opening polymer derived from 8‐methyl‐8‐methoxycarbonyl‐substituted monomer has a glass‐transition temperature of 171 °C and a 5% weight‐loss temperature of 446 °C. This polymer has excellent thermal and optical properties because of its bulky and unsymmetrical polycyclic structure in the main chain and is an alternative to glass or other transparent polymers such as poly(methyl methacrylate) and polycarbonate resin. This polymer has also been used in a wide variety of applications, such as optical lenses, optical disks, optical films, and optical fiber. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4661–4668, 2000     

Synthesis of norbornenes containing cationic mono‐ and di(cyclopentadienyliron)arene complexes and their ring‐opening metathesis polymerization

A number of classes of polynorbornenes containing cationic iron moieties within their side chains were prepared via ring‐opening metathesis polymerization with a ruthenium‐based catalyst. The iron‐containing polymers displayed excellent solubility in polar organic solvents. The weight‐average molecular weights of these polymeric materials were estimated to be in the range of 18,000–48,000. Thermogravimetric analysis of these polymers showed two distinct weight losses. The first weight loss was in the range of 204–260 °C and was due to the loss of the metallic moieties, whereas the second weight loss was observed at 368–512 °C and was due to the degradation of the polymer backbone. Cyclic voltammetry studies of the iron‐containing polymers showed that the 18 e^? cationic iron centers underwent a reduction to give the neutral 19 e^? complexes at half‐wave potential (E_1/2) = ?1.105 V. Photolysis of the metallated polymers led to the isolation of the norbornene polymers in very good yields. Differential scanning calorimetry studies showed a sharp increase in the glass‐transition temperatures up to 91 °C when rigid aromatic side chains were incorporated into the norbornene polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3053–3070, 2006     

Vinyl‐Type Polymerization of Norbornene Dicarboxylic Acid Dialkyl Esters

Summary: Poly(cis‐norbornene‐exo‐2,3‐dicarboxylic acid dialkyl esters) (alkyl = Me, Et, Pr, Bu, Pen, and Hex) are synthesized as a vinyl‐type with a palladium(II ) catalyst in high yield from easily prepared, pure exo‐monomers. The polymers show good solubility in common organic solvents and excellent thermal stability up to 330 °C. The polymers with alkyl groups larger than methyl exhibit a two‐step thermal degradation profile of an initial thermal degradation of side‐chains starting at 350 °C, followed by thermal degradation of the norbornene backbone starting at ca. 430 °C. The glass transition temperature decreases and the mechanical flexibility increases as the alkyl length of the side‐chain increases.

Normalized loss shear modulus (G″) versus temperature for polynorbornene dicarboxylic acid dialkyl esters.     

Synthesis of poly(o‐cresol) by oxidative coupling polymerization of o‐cresol

The oxidative coupling polymerization of o‐cresol was investigated using various 2‐substituted pyridine/CuCl catalysts under an oxygen atmosphere, in which 2‐phenylpyridine/CuCl and 2‐(p‐tolyl)pyridine/CuCl catalysts yielded poly(o‐cresol)s with higher regioselectivity for 1,4‐coupling. These polymerizations produced branched and crosslinked polymers in the later stages of polymerization. These polymers showed good thermal properties, such as 5% weight loss temperatures of up to 406 °C and glass transition temperatures of up to 151 °C. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 878–884     

Cationic addition polymerization of 1,4‐dioxene using gacl3 as lewis acid catalyst: Long‐lived species‐mediated polymerization

Effective cationic addition polymerization of 1,4‐dioxene, a six‐membered cyclic olefin with two oxygen atoms adjacent to the double bond, was performed using a simple metal halide catalyst system in dichloromethane. The polymerization was controlled when the reaction was conducted using GaCl₃ in conjunction with an isobutyl vinyl ether–HCl adduct as a cationogen at –78°C to give polymers with predetermined molecular weights and relatively narrow molecular weight distributions. The long‐lived properties of the propagating species were further confirmed by a monomer addition experiment and the analyses of the product polymers by ¹H NMR and MALDI–TOF–MS. Although highly clean propagation proceeded, the apparent rate constant changed during the controlled cationic polymerization of 1,4‐dioxene. The reason for the change was discussed based on polymerization results under various conditions. The obtained poly(1,4‐dioxene) exhibited a very high glass transition temperature (T_g) of 217°C and unique solubility. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Rigid-Rod benzobisthiazole polymers with reactive fluorene moieties: Synthesis and characterization

High purity 2,7-fluorenedicarboxylic acid chloride was synthesized in a multistep reaction scheme from 2,7-dibromofluorene. Subsequent polycondensation in polyphosphoric acid of 2,5-diamino-1,4-benzenedithiol dihydrochloride with terephthaloyl chloride and 2,7-fluorenedicarboxylic acid chloride led to rigid-rod benzobisthiazole polymers with reactive fluorene moieties. The proportion of fluorene in the resultant polymers was controlled through reaction stoichiometry. Soluble polymers with intrinsic viscosities as high as 33.7 dL/g (methanesulfonic acid, 30°C) were obtained if the polymerization temperature was not allowed to exceed 165°C. Insoluble, presumably crosslinked polymers were obtained at higher temperature (190–200°C). Thermal characterization of the polymers by differential thermal analysis and thermal gravimetric analysis/mass spectroscopy did not disclose any thermal transition to 450°C. Onset of weight loss in air did not occur until over 550°C.     

Cationic Polymerization Behavior of Some Vinyl Ketone Cyclodimers

Cationic polymerizations of 2,3-dihydropyran derivatives, methyl isopropenyl ketone cyclodimer (MIPKD), chloromethyl vinyl ketone cyclodimer (CMVKD), and methyl isopropenyl ketone-chloromethyl vinyl ketone cyclocodimer, D(MIPK-CMVK), were investigated in the presence of various Lewis acids at 0°C. These monomers were found to undergo cationic polymerization to give low molecular weight polymer which consisted mainly of a vinylene structure. However, the ring-opening polymerization was found to occur to a minor extent in cationic polymerizations of MIPKD and D(MIPK-CMVK) cyclodimer.     

Low glass transition temperature fluorocarbon ether bibenzoxazole polymers

Fluorocarbon ether bis(o-aminophenol) monomers were prepared by a multistep synthetic route based on the copper-promoted coupling of 4-iodophenyl acetate with 1,8-diiodoperfluoro-3,6-dioxaoctane, 1,11-diiodoperfluoro-3,9-dioxaundecane, 1,14-diiodoperfluoro-5,10-dimethyl-3,-6,9,12-tetraoxatetradecane, and 1,17-diiodoperfluoro-3,6,9,15-tetraoxaheptadecane. Acetic acidpromoted polycyclocondensations of the monomers with long-chain fluorocarbon ether-diimidate esters and -dithioimidate esters led to linear fluorocarbon ether-bibenzoxazole polymers soluble in 1,1,1,3,3,3-hexafluoroisopropanol and 1,1,2-trichloro-1,2,2-trifluoroethane. Polymer structures were verified by elemental and infrared spectral analysis. The polymers were rubbery gums and could be obtained in the inherent viscosity range of 0.20–0.79 dlg^?1. Selection of monomers governed the glass transition temperatures of the resultant polymers. As expected, the polymers exhibited lower glass transition temperatures with increased fluorocarbon ether content, a minimum value of ?58°C being achieved. None of the polymers exhibited crystalline melt temperatures. Based on thermogravimetric analysis data, the thermooxidative stability of the polymers tended to decrease with increased fluorocarbon ether content. Onset of breakdown during thermogravimetric analysis in air occurred in the 350–400°C range. Isothermal aging of the polymers in air indicated good thermooxidative stability at 260°C; only 5% weight loss was recorded after 200 hr.     

Preparation and characterization of novel thermostable polyamides bearing different photoactive pendent architectures with antibacterial properties

Three diamine monomers with different derivatives of imidazole heterocyclic ring, aryl ethers and electron withdrawing trifluoromethyl groups in the backbone were synthesized and used in polycodensation reaction with various aliphatic and aromatic dicarboxylic acids for preparation of a series of novel polyamides(PAs). The PAs were obtained in high yields and possessed inherent viscosities in the range of 0.26-0.75 d L/g. All of the polymers were amorphous in nature,showed outstanding solubility and could be easily dissolved in amide-type polar aprotic solvents. They showed good thermal stability with glass transition temperatures between 162-302 ℃. Thermogravimetric analysis showed that all polymers were stable, with 10% weight loss recorded above 421 ℃ in N_2 atmospheres. All the PAs presented fluorescence upon irradiation with ultraviolet light and thus showed promise for applications in electroluminescent devices. The monomers and PAs were also screened for antibacterial activity against Gram positive and Gram negative bacteria.     

Synthesis and optical properties of fluorinated poly(arylene ether phosphine oxide)s

Fluorinated dihydroxy phosphine oxide monomers were synthesized via chlorination, Grignard, and demethylation techniques. The prepared monomer was successfully polymerized with each of the three perfluorinated monomers (decafluorobiphenyl, decafluorobenzophenone, and pentafluorophenylsulfide) by nucleophilic aromatic substitution. The average molecular weight ranged between 7800 and 14,900 g/mol. The glass‐transition temperatures of the polymers were registered in the range of 185–235 °C, and all the polymers exhibited high thermal stability up to 326–408 °C. The results of the refractive‐index measurements indicated control of the refractive index between 1.5181 and 1.5536 and an optical loss of 0.53 dB/cm at 1550 nm. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1497–1503, 2003     

Synthesis of novel hyperbranched poly(ester‐amide)s based on neutral α‐amino acids via “AD + CBB′” couple‐monomer approach

A series of novel hyperbranched poly(ester‐amide)s (HBPEAs) based on neutral α‐amino acids have been synthesized via the “AD + CBB′” couple‐monomer approach. The ABB′ intermediates were stoichiometrically formed through thio‐Michael addition reaction because of reactivity differences between functional groups. Without any purification, in situ self‐polycondensations of the intermediates at elevated temperature in the presence of a catalyst afforded HBPEAs with multihydroxyl end groups. The degrees of branching (DBs) of the HBPEAs were estimated to be 0.40–0.58 and 0.24–0.54 by quantitative ¹³C NMR with two different calculation methods, respectively, depending on polymerization conditions and structure of monomers. The influences of catalyst, temperature, and intermediate structure on the polymerization process and molecular weights as well as properties of the resultant polymers were investigated. FTIR, NMR, and DEPT‐135 NMR analyses revealed the branched structure of the resultant polymers. The HBPEAs possess moderately high molecular weights with broad distributions, glass transition temperatures in the range of ?25.5 to 36.5 °C, and decomposition temperatures at 10% weight loss under nitrogen and air in the regions of 243.4–289.1 °C and 231.4–265.6 °C, respectively. Among them, those derived from D ,L ‐phenylalanine display the lowest degree of branching, whereas the highest glass transition temperature and the best thermal stability. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Phenylated polyquinoxalines from bis(phenylglyoxaloyl)benzene

Phenyl-substituted polyquinoxalines of unusually high oxidative-thermal stability were prepared by one-step solution condensations of aromatic tetraamines with 1,4-bis-(phenylglyoxaloyl)benzene and 1,3-bis(phenylglyoxaloyl)benzene. The final polymers thus obtained show exceptionally good solubility in a variety of common organic solvents, such as chloroform, tetrachloroethane, dichlorobenzenes, and certain phenols. Polymerizations in these solvents lead to polyquinoxalines of high molecular weight at reaction rates which depend upon the solvent used. The phenylated polyquinoxalines exhibited glass transition temperatures between 253 and 317°C and polymer decomposition temperatures between 515 and 540°C, depending upon structure. Isothermal decomposition at 400°C in air showed a strong dependency of weight loss on structure. Tough, flexible films were cast from solutions.     

含1,3,4-噁二唑甲壳型液晶聚合物的合成与表征

甲壳型液晶聚合物（mesogen-jacketed liquid crystal polymer,MJLCP）是1987年由周其凤教授[1]首先提出的概念.从化学结构看,甲壳型液晶聚合物属于侧链型,由烯类单体经链式聚合制得,容易得到高分子量的产物,具有一般柔性侧链型液晶聚合物的一些优点.但是与柔性侧链型液晶聚合物不同的是,MJLCP分子中的刚性液晶基元是通过腰部或重心位置与主链相联结的,在主链与刚性液晶基元的侧基之间只有很短或者没有柔性间隔基.由于在这类液晶聚合物的分子主链周围空间内刚性液晶基元的密度很高,分子主链被由液晶基元形成的外壳所包裹并被迫采取相对伸直的刚性链构象.因此,这类液晶聚合物又和主链型刚性链液晶聚合物相似,具有较明显的链刚性.近年来,周其凤课题组围绕甲壳型液晶聚合物深入开展了分子设计与合成、分子结构与性能等多方面的研究.其中,设计合成具有特定功能的甲壳型液晶聚合物是在以往研究工作和学科交叉融合的基础上发展起来的一项新的研究工作.将一些有特殊功能的基团引入到甲壳型液晶聚合物中会使其具有崭新的特性.     

Synthesis and characterization of new,soluble polyazomethines bearing fluorene and carbazole units in the backbone and solubility‐improving moieties in the side group

A series of novel, soluble polyazomethines bearing fluorene and carbazole moieties in the main chain and solubility‐improving moieties in the side group (dibutyl, ethylhexyl, thienylethyloxy, furyl, and fluorenyl) were synthesized. Good‐quality films of these polymers were prepared through the conventional solution‐casting and drying processes. Depending on the polymer structure, some polymers showed a glass‐transition temperature (107–167 °C) and others showed a melting temperature (285–341 °C). The temperature of 5% weight loss under nitrogen atmosphere of the polymers ranged from 370 to 464 °C. The results indicated that the side groups incorporated into the polyazomethine structure in this work improved the polymer solubility without sacrificing thermal stability. Depending on the polymer structure, some of the polymers were crystalline whereas others were amorphous. All the polyazomethines were solution‐processable and thermally stable, making them potential candidate materials for applications in microelectronics and aerospace. Moreover, the features in the UV–visible spectra of the polyazomethines were redshifted as compared with those of the monomers from which the polymers were synthesized, indicating that these polymers, if combined with an appropriate doping agent to improve the light‐emitting and conducting abilities, may be good candidate materials for optoelectronic devices. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 825–834, 2004     

Adamantyl-substituted phenolic polymers

4-(1-Adamantyl)phenol was synthesized via Friedel-Crafts reaction of 1-bromoadamantane and phenol. Substitution in the phenol para position forces polymerization to occur only in the ortho positions to give a linear polymer. Variations in formaldehyde amount, reaction time, and catalyst were evaluated. Increasing the amount of paraformaldehyde increased formation of cyclic octamer, an easily identified by-product due to its insolubility in common organic solvents. The cyclic octamer was acetylated to give a soluble model compound for comparison to acetylated polymers by IR and NMR. All of the synthetic variations employed produced low molecular weight polymers as indicated by NMR end-group analysis and SEC. The polymers showed number-average molecular weights of ca. 3000 (versus polystyrene standards by SEC), and exhibited glass transition temperatures ranging from 175–230°C, an increase of ca. 100°C over unsubstituted and para-alkyl substituted analogs. All of the samples exhibited a 10% weight loss at 400°C in nitrogen, indicating thermal stability much greater than the parent and alkyl-substituted polymers. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of novel photoisomerizable liquid crystalline polymers containing cinnamoyl groups

A series of novel liquid crystalline monomers and polymers incorporating phenylbenzoate or phenylcinnamate segments as mesogenic cores have been synthesized to investigate the sensitivity of the photochromic cinnamoyl derivatives and to overcome the defects of the thermal instability of azobenzene. Their liquid crystalline, thermal, and photoinduced properties of all monomers and polymers were characterized. The polymers showed excellent solubility in common organic solvents such as CHCl₃, toluene, and DMF and exhibited good thermal stability with decomposition temperatures (T_d) at 5% weight loss greater than 340 °C and about 50% weight loss occurred beyond 430 °C under nitrogen atmosphere. The pitch length (about 574 nm) of the synthesized cholesteric polymeric film ( CP2 ) was estimated using scanning electron microscopy. These photochromic polymers exhibited strong UV–vis absorption maxima at about 264 or 320 nm. Moreover, photo induced configurational E/Z isomerization further changed the π‐electron conjugation systems leading to a decrease at the π‐π* transition and an increase in the range of 300 nm to 400 nm for photochromic copolymers. The thermal stability of the Z‐structural segment was confirmed by heating the polymer at 50 °C for over 5 h. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1289–1304, 2008     

Radiation-induced polymerization at high dose rate. IV. Chloroprene in bulk

Bulk polymerization of chloroprene was studied at 25°C in a wide does rate range. Variations of the rate of polymerization (R_p) and molecular weight as a function of does rate were essentially the same as those in several monomers that are capab;e of radical and cationic polymerizations. The polymerization proceeds with radical mechanism at low dose rate ans with radical and cationic mechanism concurrently at high dose rate. The number-average molecular weight of the high-dose-rate was ca. 2400. Microstructure of the polymers was mainly of trans-1,4 unit with small fraction of cis-1,4 and 3,4-vinyl unit. Fractions of the vinyl unit and the inverted unit in trans-1,4 sequence which increased at high does rate inflected the change of dominant mechanism of polymerization.