Studies on photo-crosslinkable polyphosphoramide esters containing divanillylidene cycloalkanone units

Two series of photo-crosslinkable polyphosphoramide esters were synthesized from 2,5-bis(4-hydroxy-3-methoxy benzylidene)cyclopentanone and 2,6-bis(4-hydroxy-3-methoxy benzylidene)cyclohexanone with various N-arylphosphoramide dichlorides by interfacial polycondensation using hexadecyl trimethylammonium bromide as phase transfer catalyst at ambient temperature. The resulting polymers were characterized by inherent viscosity, Fourier transform infra-red, ¹H and ¹³C nuclear magnetic resonance spectroscopy. The thermal stability of the polymers synthesized was evaluated by thermogravimetric analysis. These polymers were studied for their photo-chemical reactions. The divanillylidene cycloakanone groups in the polymer chain function as photo-active centres. Crosslinking proceeds via 2π + 2π cycloaddition reaction of the divanillylidene cycloalkanone moieties. The rate of crosslinking decreases with increase in the size of the cycloalkanone ring, while the thermal stability increases with increase in the size of the cycloalkanone ring.     

Synthesis,spectral, and thermal characterization of photoreactive epoxy resin containing cycloalkanone moiety in the main chain

Dual functional epoxy resins were synthesized by solution polycondensation of 2,6‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclohexanone and 2,5‐bis(4‐hydroxy‐3‐methoxy benzylidene)cyclopentanone with epichlorohydrin. The synthesized epoxy resins were characterized systematically for their structure by UV, Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR spectroscopic techniques. Thermal characterization of synthesized epoxy resins was carried out by thermogravimetric analysis, and differential scanning calorimetry (DSC) under nitrogen atmosphere. The self extinguishing property of synthesized oligomers was studied by determining limiting oxygen index (LOI) values using Van Krevelen's equation. X‐ray analysis showed that the epoxy resins containing cyclopentanone have higher degree of crystallinity. The photoreactive property of the synthesized epoxy resins in solution and film states was investigated by UV–Vis spectroscopy. The photocross‐linking proceeds through the dimerization of olefinic chromophore present in the main chain of the oligomer via 2π + 2π cycloaddition reaction. The influence of photoacid generator on the rate of photocross‐linking of epoxy resin was studied by FTIR. UV irradiation of the epoxy resin in presence of photoacid generator produces aromatic sulfonium cation radicals and aromatic radicals which initiate the cationic ring‐opening polymerization of oxirane ring. The photoreactivity studies of the oligomers by FTIR and DSC indicated the presence of dual functionality in the synthesized epoxy resins. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermotropic main‐chain liquid‐crystalline photodimerizable poly(vanillylidenealkyloxy alkylphosphate ester)s containing a cyclopentanone moiety

A new class of main‐chain liquid‐crystalline photodimerizable vanillylidene‐containing alkylpolyphosphate esters were synthesized from 2,5‐bis[m‐hydroxyalkyloxy(vanillylidene)] cyclopentanones with various alkylphosphoro‐ dichloridates by solution polycondensation in chloroform at ambient temperature. Their chemical structures were confirmed by FT‐IR, ¹H, ¹³C and ³¹P NMR spectroscopic analysis. Dilute‐solution viscosity values were measured in order to obtain the intrinsic viscosities of the synthesized polymers. Mesogenic properties and phase behavior were investigated by the use of hot‐stage optical polarized microscopy and differential scanning calorimetry. Thermogravimetric analysis revealed that all of the polymers were stable up to 170–230 °C and decomposed with high char yields. The shorter methylene‐chain‐containing polymers did not show a liquid‐crystalline phase, while the longer methylene‐chain‐ containing polymers showed grainy and nematic textures. The T_g, T_m and T_i values of the polymers decreased with increasing flexible methylene chain length in the polymer backbones. The photocrosslinking properties of the polymers were studied by UV light/UV spectroscopy; the crosslinking proceeds via 2π–2π cycloaddition reactions of the vanillylidene exocyclic double bonds of the polymers. The rate of crosslinking was faster for the pendant ethoxy‐containing polymers than that of the pendant methoxy‐containing polymers. Copyright © 2005 Society of Chemical Industry     

Synthesis,spectral, and thermal characterization of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain derived from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone

A series of photosensitive poly(ether–ester)s containing α,β‐unsaturated ketone moieties in the main chain were synthesized from 2,6‐bis[4‐(3‐hydroxypropyloxy)‐3‐methoxybenzylidene]cyclohexanone (BHPMBCH) and aliphatic and aromatic diacid chlorides. The diol precursor, BHPMBCH, was synthesized from 2,6‐bis(4‐hydroxy‐3‐methoxybenzylidene)cyclohexanone and 3‐bromo‐1‐propanol. The solubility of the polymers was tested in various solvents. The intrinsic viscosity of the synthesized polymers, determined by an Oswald viscometer, was found to be 0.06–0.80 g/dL. The molecular structures of the monomer and polymers were confirmed by Fourier transform infrared, ultraviolet–visible, ¹H‐NMR, and ¹³C‐NMR spectral analyses. The thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. The thermogravimetric analysis data revealed that the polymers were stable up to 220°C and started degrading thereafter. The thermal stability initially increased with increasing spacer length and then decreased due to negative effects of the spacer. The self‐extinguishing properties of the synthesized polymers were studied by the determination of the limiting oxygen index values with Van Krevelen's equation. In addition, the photocrosslinking properties of the polymer chain were studied with UV spectroscopy, and we observed that the rate of photocrosslinking increased significantly with increasing methylene carbon chain length of the acid spacer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Photocrosslinkable phosphorus containing homo‐ and copolyesters: Synthesis,characterization, and photosensitive properties

A new series of homo‐ and copolyphosphoramide esters containing pendant chlorine group was synthesized from dihydroxy chalcones, N‐(4‐chlorophenyl)phosphoramidic dichloride, and terephthaloyl chloride by interfacial polycondensation technique. The diol monomers were prepared by condensing 4‐hydroxy benzaldehyde and 3‐methoxy‐4‐hydroxybenzaldehyde with 4‐hydroxy acetophenone. The synthesized monomers and polymers were characterized by UV, IR and ¹H, ¹³C, and ³¹PNMR spectroscopic techniques. Molecular weight of the polymers was determined by gel permeation chromatography. The thermal properties of the polymers were studied by thermogravimetric analysis and differential scanning calorimetry under nitrogen atmosphere. The photo‐crosslinking ability of the polymers in various solvents was observed with UV spectrophotometer. The photocrosslinking proceeds via 2π +2π cycloaddition reaction of α, β‐unsaturated carbonyl group. The comparison study on the rate of photocrosslinking of homo and copolymers was also carried out. The chemical and physical properties of these polyesters are compared with those of the unsubstituted polyesters and the results are discussed herein. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and study of the effect of carboxyvinyl group position on the properties of polyamides. Crosslinked polymers

Several aromatic polyamides containing carboxyvinyl bonds in the main chain were synthesized by self-condensation from β-(2-,3-,4-aminophenyl)propenoic acid using the phosphorylation method. In addition, aromatic polyamides containing carboxyalkyl bonds in the backbone were synthesized under the same conditions for comparative purposes (model polyamides) and used as pattern. The model polyamides were synthesized from 3-,4-aminophenyl acetic acid and β-(3-aminophenyl)propanoic acid. Polymers were characterized by UV–vis, FT-IR and ¹H-NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and inherent-viscosity measurement. The effect of the carboxyvinyl group position in the aromatic ring was correlated to polyamides properties. Thereby, solubility, thermal stability, viscosities, optical properties, and polymers crosslinking were studied. Some polyamides were soluble in polar solvents and inorganic acids. Upon thermal curing crosslinked polymers were obtained. The thermal stability and crosslinking of polyamides were evaluated with respect to position of carboxyvinyl in the aromatic ring. The crosslinked polymers exhibited improved thermal stability.     

A series of novel high-temperature-resistant multiwall carbon nanotubes dispersants: Polyphenylene sulfones with pyrene groups in main chain

A series of polyphenylene sulfones were synthesized with pyrene groups in the main chain. Using a traditional Suzuki coupling reaction followed by a reduction, the pyrene-containing monomer was synthesized as the diphenol. A series of copolymers were synthesized using this new monomer, a biphenyldiphenol, and 4,4′-difluorodiphenylsulfone. These polymers were characterized using ¹HNMR and FTIR spectroscopy. The introduction of rigid pyrene groups provided these new polymers with good thermal stability and mechanical strength. In this work, these polymers are shown to functionalize and disperse multiwall carbon nanotubes (MWCNTs). The associations of our copolymers to the MWCNTs appear to operate through pi stacking interactions between the pyrene group and the sidewalls of the MWCNTs, referred to in this article as f-MWCNTs. The dispersibility of f-MWCNTs in solvents and polymer matrixes was systematically studied by preparation of f-MWCNTs/polyphenylene sulfone (PPSU) composites with various f-MWCNTs content. Improvements in the dispersability of f-MWCNTs in PPSU resin result in enhancement of the mechanical and thermal properties of f-MWCNTs/PPSU composites. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48379.     

Electroactive Polyimides: Synthesis,Characterization and Photophysics

A series of aromatic electroactive polyimides bearing p-phenoxy pendant at main chain were synthesized as fluorescent materials. The PIs were prepared from electroactive diamine N¹-(4-aminophenyl)-N¹-(4-phenoxyphenyl)benzene-1,4-diamine. The structure of the polyimides was characterized by the fourier transform infrared spectroscopy, Carbon, Hydrogen and Nitrogen analyses, and gel permeation chromatography. The polyimides were analyzed for their photophysical and electrochemical properties by ultraviolet–vis spectral analysis photoluminescence spectroscopy and cyclic voltammetry. Thermal stability of the polyimides was evaluated by thermogravimetric analysis and differential scanning calorimetry. The observed behavior of our synthesized polyimides revealed their shallow highest occupied molecular orbital levels, low E_g, blue light emission and stable redox behavior, and good thermal and mechanical stability making our synthesized polyimides useful for future optoelectronics.     

Investigation on thermotropic liquid crystalline and photocrosslinkable polyarylidene arylphosphate esters containing cyclohexanone units

Two series of novel liquid crystalline-cum-photocrosslinkable divanillylidene cyclohexanone containing polymers have been synthesized from 2,6-bis[m-hydroxyalkyloxy(vanillylidene)]cyclohexanone [m=6, 8, 10] with different arylphosphorodichloridates (naphthyl, biphenyl) by solution polycondensation method at ambient temperature. Their chemical structures were confirmed by FT-IR, ¹H, ¹³C and ³¹P NMR spectroscopy. The intrinsic viscosity values were measured to find out molecular weight of the synthesized polymers. The mesogenic properties and phase behaviors were investigated with differential scanning calorimetry and hot stage optical polarized microscopy. The experimental results demonstrated that the mesogenic transition and isotropization temperature gradually decreases with increase in even number of methylene spacer of the polymer chain. All the polymers showed anisotropic behavior under hot stage optical polarized microscope (HOPM). The thermal behaviors of the polymers were studied by thermogravimetric analysis and stable between 292 and 330 °C. The photocrosslinking of the polymers was investigated in thin film by UV light/UV spectroscopy and the cyclobutane ring formation via 2π-2π cycloaddition reactions of the divanillylidene exo-cyclic double bond of the polymer backbone. The pendant naphthyloxy containing polymers show faster crosslinking than the pendant biphenyloxy containing polymers.     

Fluorene‐based click polymers: Relationship between molecular structure and nonlinear optical properties

To further understand the relationship between the polymer structure and nonlinear optical (NLO) property, in this article, three fluorene‐based triazole functional polymers with different linked chains were designed and controllably prepared by click chemistry method. The structures and properties of these polymers were characterized and evaluated with Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, fluorescence spectra, dynamic state laser light scattering, thermogravimetric analysis, and NLO analyses. The results exhibited that the target polymers displayed good solubility, high thermal stability, and well NLO properties. The relationships between molecular structures and optical properties were investigated by both theoretical simulation and experimental results. It was found that the rigid conjugated linked chain between triazole and chromophore can effectively enhance the NLO properties of the resultant polymers. The suitable rigid and flexible groups in the triazole polymers will result in good thermal stabilities. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40878.     

Synthesis and characterization of α‐methylstilbene‐ and azobenzene‐based thermotropic liquid crystalline polymers

A series of combined liquid crystalline poly(bis‐4,4′‐oxy‐α‐methylstilbene‐4‐substituted (X) phenylazo‐4′‐phenyloxydecylphosphate ester)s bearing photoreactive mesogenic units were synthesized. FTIR and ¹H NMR spectroscopy confirmed the structures of these polymers. The inherent viscosities of the polymers were found to be in the range 0.45–0.65 dL g^?1. Polarizing optical microscopy (POM) exhibited birefringent liquid crystalline melt properties. The thermal properties of all of the polymers were studied by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The photochemical properties of these polymers were studied by UV‐visible and fluorescence spectroscopy. The influence of the photoinduced E–Z (trans–cis) isomerization of the various terminal substituents of the side‐chain azobenzenes was investigated. The kinetics of the photoisomerization process reveal the switching times for the conversion between the trans‐ and cis‐ forms of the azobenzene units. The photo‐optical properties of these polymers exhibited layered smectic phases and showed good photoinduced properties in their mesomorphic states. Copyright © 2005 Society of Chemical Industry     

Photosensitive poly(urethane acylsemicarbazide)s with azobenzene chromophores in the main chain

Poly(urethane acylsemicarbazide)s were synthesized with a two‐step process: (1) the in situ generation of diisocyanate through the thermal decomposition of an azobenzene‐containing precursor diazide and a reaction with ester/ether polyols to form an isocyanate‐terminated prepolymer and (2) chain extension in N,N‐dimethylacetamide with aliphatic or aromatic dihydrazides. Films cast from N,N‐dimethylacetamide solutions were characterized with attenuated total reflection/Fourier transform infrared spectroscopy, and the thermal properties were studied with thermogravimetric analysis and differential scanning calorimetry. The effects of the hard‐segment content and chain extenders on the static and dynamic mechanical properties were investigated. The photoresponsive behavior of the polymers and the effects of variations in the chromophore concentration and chemical composition on the kinetics of photoisomerization were investigated with ultraviolet–visible spectroscopy, which revealed that the rates were independent of the chromophore concentration. The photomechanical behavior, assessed with creep‐recovery measurements, proved that the systems underwent photochemical isomerization upon irradiation with ultraviolet light. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 444–454, 2004     

Investigation of liquid crystalline and photocrosslinkable poly[4‐x‐phenyl‐4′‐(m‐methacryloyloxyalkyloxy)cinnamate]s

Three series of liquid‐crystalline‐cum‐photocrosslinkable polymers were synthesized from 4‐x‐phenyl‐4′‐(m‐methacryloyloxyalkyloxy)cinnamates (x = ? H, ? OCH₃ and ? CN; m = 6, 8 and 10) by free radical solution polymerization using azobisisobutyronitrile as an initiator in tetrahydrofuran at 60 °C. All the monomers and polymers were characterized using intrinsic viscosity, and FTIR, ¹H NMR and ¹³C NMR spectroscopy. The liquid crystalline behavior of these polymers was examined using a hot stage optical polarizing microscope. All the polymers exhibited liquid crystalline behavior. The hexamethylene spacer‐containing polymers exhibited grainy textures; in contrast, the octamethylene and decamethylene spacer‐containing polymers showed nematic textures. Differential scanning calorimetry data confirmed the liquid crystalline property of the polymers. Thermogravimetric analysis revealed that all the polymers were stable between 236 and 344 °C in nitrogen atmosphere and underwent degradation thereafter. As the methylene chain length increases in the polymer side‐chain, the thermal stability and char yield of the polymers decrease. The photocrosslinking property of the polymers was investigated using the technique of exposing the polymer solution to UV light and using UV spectroscopy. The crosslinking reaction proceeds via 2π–2π cycloaddition reactions of the ? CH?CH? of the pendant cinnamate ester. The polymers containing electron‐releasing substituents (? OCH₃) showed faster crosslinking than the unsubstituted polymers and those containing electron‐withdrawing substituents (? CN). Copyright © 2007 Society of Chemical Industry     

New linear π-conjugated polymers via Suzuki coupling of (1Z, 3Z)-1,4-dibromo-1,4-diaryl-buta-1,3-diene with aromatic diborates: Synthesis and photophysical properties

A series of new linear π-conjugated polymers have been synthesized via Suzuki coupling of (1Z, 3Z)-1,4-dibromo-1,4-diaryl-buta-1,3-diene with aromatic diborates. The structures were characterized by NMR spectroscopy, IR spectroscopy and GPC. All of them exhibit good thermal stability with high decomposition temperature over 340 °C. It was found that the absorption and emission of the polymers can be adjusted through changing the side aromatic group, and the partial twisted structure of two aromatic groups at the end carbon of buta-1,3-diene unit can hinder the interchain interaction of conjugated main chain and improve the photophysical properties of the polymers in the solid state. The electrochemical and electroluminescent properties of the polymers were primarily studied.     

Synthesis and characterization of poly (amide-imide-imide)s based on diacids with bulky m-chloro phenyl moiety and rigid pyridine moiety

A series of novel aromatic diamines containing kinked m-chloro phenyl moiety was synthesized by the reaction of m-chloro benzaldehyde with 2,6-dimethyl aniline. The tetraimide diacid was synthesized by using the prepared diamine with benzophenone tetracarboxylic acid dianhydride (BPTDA) and p-amino benzoic acid. The polymers were prepared by treating the tetraimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified by ¹H-NMR, FTIR,¹³C-NMR and elemental analysis. The polymers showed excellent thermal stability, solubility and mechanical properties. Their structure–property relationship was studied by comparing these m-chloro polymers with polymers containing rigid Pyridine moiety.     

Spectral,thermal, and photoreactivity studies on epoxy resin containing benzylidene units in the main chain

A photosensitive epoxy resin was synthesized from bis(4‐hydroxy ‐3‐methoxy benzylidene) acetone and epichlorohydrin using solution polycondensation method. The prepared epoxy resin was characterized by UV, IR, ¹H NMR, and ¹³C NMR spectroscopy. The thermal stability of the epoxy resin was assessed by thermogravimetric analysis. The glass transition temperature of the polymer was determined by differential scanning calorimetry. The photocrosslinking property and photopolymerizing ability of the epoxy resin were studied in film and solution state using UV spectroscopy. The effect of photo acid generator and sensitizer on photosensitivity of the resin was also investigated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis,characterization, and properties of a novel epoxy resin containing both binaphthyl and biphenyl moieties

A new epoxy resin containing both binaphthyl and biphenyl moieties in the skeleton (BLBPE) was synthesized and confirmed by electrospray ionization mass spectroscopy, ¹H‐nuclear magnetic resonance spectroscopy, and infrared spectroscopy. To evaluate the combined influence of two moieties, one epoxy resin containing binaphthyl moiety and another containing biphenyl moiety were also synthesized, and a commercial biphenyl‐type epoxy resin (CER3000L) was introduced. Thermal properties of their cured polymers with phenol p‐xylene resins were characterized by differential scanning calorimetry, dynamic mechanical, and thermogravimetric analyses. The cured polymer obtained from BLBPE showed remarkably higher glass transition temperature and lower moisture absorption, as well as comprehensively excellent thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis, characterization and liquid crystalline behavior of poly(monomethyl itaconate)s with new pendant cholesterol moieties

In order to investigate the effects of cholesteryl pendant groups on inducing liquid crystalline (LC) phase formation, a new series of cholesteryl-modified poly(monomethyl itaconate) (PMMI-Chol-C₆) have been synthesized from poly(monomethyl itaconate) (PMMI) and 6-(cholesteryloxycarbonyloxy) hexanol (Chol-C₆) with different degrees of substitution (DS_chol). All the obtained compounds were characterized by conventional spectroscopic methods. The DS_chol values of the modified PMMI were obtained by ¹H NMR spectroscopy and conductometric titration. The inherent viscosities of polymers were determined by an Ubbelohde viscometer at 35 °C in DMSO solution. The resulting products of modified PMMA polymers were soluble in a variety of organic solvents, and the solubility improved by increasing the DS_chol. Thermal behavior and optical properties of Chol-C₆ and PMMI-Chol-C₆ polymers were investigated by thermal gravimetric analysis, differential scanning calorimetry and hot-stage polarizing optical microscopy. The glass transitions of the modified PMMI polymers occurred at lower temperatures than the parent PMMI. It was found that among the synthesized polymers with different molar ratios of the substitution, only the PMMI-Chol-C₆ (1) polymer bearing 77 mol% of the side chains, with reduced melting point and increased thermal stability, formed thermotropic liquid crystalline smectic phases. This polymer exhibited wider mesophase than the mesogenic side chain Chol-C₆ and amorphous morphology. The results of a comparative study on the structure and properties of the polymers showed that liquid crystalline polymers may be achieved through the attachment of mesogenic cholesterol side chain onto the main chain via methylene chains of side branches.     

Photoresponsive Functionalized Vinyl Cinnamate Polymers: Synthesis and Characterization

A series of functionalized vinyl cinnamate monomers were synthesized by the reaction of hydroxyethylmethacrylate and various substituted cinnamoyl chlorides. Electron donating and accepting functional groups such as −OCH₃, −Cl and −NO₂ were introduced at the para position of cinnamoyl chloride. Homopolymerization of the synthesized monomers were carried out in dimethylformamide using azobisisobutyronitrile as a free radical initiator at 80°C for 12h. The structures of the synthesized monomers and their polymers were characterized using Fourier transform infrared (FTIR), ¹H and ¹³C nuclear magnetic resonance spectroscopic techniques. Solid-state crosslinking of the above photosensitive polymers was studied by UV and FTIR spectroscopic techniques. The effects of various functional groups and the addition of sensitizer (benzophenone) on the photocrosslinking nature of the polymers were studied. The mechanism of photocrosslinking is a (2+2)π electron cycloaddition and not cis–trans isomerization in the functionalized polyvinylcinnamates. © 1997 SCI     

Synergistic effect of alkyl lactate functional groups on properties of methacrylate polymers

In this work, four novel different alkyl lactate methacrylate monomers were synthesized through azeotropic esterification method by reacting methyl, ethyl, propyl and butyl lactates with methacrylic acid. The prepared monomers were polymerized through solution polymerization technique and both monomers and polymers were analyzed by FTIR, ¹H NMR and ¹³C NMR spectroscopy techniques to elucidate the structure and to confirm their formation. Increasing the number of methylene units in alkyl lactate side chain decreases the glass transition temperature (T_g) of the polymers. Average molecular interchain spacing (〈R〉) of polymers was obtained from the wide-angle X-ray diffraction measurement and the values ranged from 6.26 to 7.18 Å based on the length of alkyl lactate group. The prepared polymers showed hygroscopic property and their moisture absorption was in the range of 10–24% (w/w) depending upon the length of alkyl lactate moiety, relative humidity and time. These polymers have the potential for hydrogel applications owing to their increased moisture absorption capacity. Both polymethyl and propyl lactate methacrylate showed two distinct and prominent thermal degradations whereas polyethyl and butyl lactate methacrylates showed only a single distinct and prominent thermal degradation step. An interesting result of as-synthesized polymers showed odd–even chain length effect in the properties of 〈R〉, moisture uptake and thermal stability.