Compatibility and molecular structure of rubbers

Compatibility of 17 pairs of rubbers has been investigated by means of phase separation, glass transition measurements and electron microscopy. Influence of structural details like side chains, configuration of monomer units and distance between double bonds in the chain on the compatibility of polymers has been elucidated. Experimental data lead to following results: Side chains have the strongest influence on compatibility; poly(isobutene) and poly(pentenamer), e.g., are highly incompatible. With decreasing influence on compatibility follows the configuration of the double bond in the polymer chain. Polymers with equal configuration are more compatible than polymers with different configuration. The structural detail with the weakest influence on compatibility is the distance between double bonds along the polymer chain. Poly(octenamer) and poly(pentenamer), e.g., with 6 and 3 methylene groups between the double bonds are less compatible than poly(butadiene) and poly(pentenamer) with a distance of 2 and 3 methylene groups. Cis-poly(pentenamer) and natural rubber were found to be highly compatible although electron micrographs show domains with an average diameter of 50 Å.     

FTIR equivalent weight determination of perfluorosulfonate polymers

Fourier transform infrared (FTIR) and attenuated total reflectance (ATR) spectroscopy studies of the sulfonyl fluoride, potassium salt, and sulfonic acid forms of long and short side chain perfluorosulfonate polymers revealed bands indicative of the sidegroup and backbone compositions, endgroups on the main chain, water content, monomer concentration, and degree of salt hydrolysis. The equivalent weight (EW) of the polymer was obtained by titration and NMR measurements which were then calibrated to either the C F/C O C absorbance band ratio for thin (<1.1 mil) films or to a C F/SO₂F absorbance band ratio for thick films (5 to 25 mils). An FTIR measurement of the film thickness based on the C F group concentration was found to be both a function of the actual thickness and the EW; a method for compensating for this EW dependence is described. Esterification and fluorination of the polymers yielded FTIR measurements of the endgroup compositions on the polymer backbone which were shown to consist of  COF,  COOH,  CO₂CH₃, and  CFCF₂ groups. Thermogravimetric Analysis Infrared (TGA‐IR) spectroscopy of the acid form polymers indicates that degradation begins by the decomposition of the  SO₃H group at 320°C followed by bulk deterioration above 400°C. The FTIR techniques detailed herein have been developed for accurate, reproducible, and rapid compositional measurements of Nafion® and other perfluorosulfonate polymers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A new imine coupled pyrrole-carbazole-pyrrole polymer: Electro-optical properties and electrochromism

In this study, imine bond coupled pyrrole-carbazole-pyrrole monomers were synthesized in four steps and then directly polymerized onto ITO/glass surface via potentiodynamic electrochemical process. Electrochemical and optical bad gap of these monomers and polymers were calculated by using cyclic voltammetry and UV-Vis absorption spectroscopy. Conductivity of the polymers with different alkyl side-chain was determined by using four point probe technique. Length of the side-alkyl chain influence iodine doping and also conductivity of polymers. As a result of the spectroelectrochemical measurements, the orange color of film changed to green color with applied potential and the polymer was found to be suitable material for electrochromic applications.     

High temperature stable photopatternable copolymers: Synthesis,optical properties,and photopatterning process studies

Photopatternable copolymers and photopatterning processes for high temperature stable optical elements have been studied. The photopatternable copolymers were synthesized from methyl methacrylate and methacrylic ester comprising a nonconjugate carbon–carbon double bond side chain and epoxy side chain. Their optical properties were investigated on film samples doped with m-benzoylbenzophenone (BBP). After irradiating with UV light, insoluble polymer was formed in a high yield at higher temperature, resulting in changes in thickness and refractive index, which were precisely controlled by the exposure energy of UV light. The two step photopatterning processes were carried out by means of UV irradiations with and without a photomask bearing a grating pattern followed by removal of unreacted BBP to draw an optical pattern on the polymer material with cross-linking. Further photoreaction was also performed to cure the polymer by exposure with a high energy UV lamp containing shorter wavelength light after the patterning process. By a combination of the patterning process and the postcuring process, an optical grating fabricated from these copolymers showed a heat stability up to 160°C. © 1994 John Wiley & Sons, Inc.     

Effect of polymer composition on performance properties of maleate-vinyl ether donor-acceptor UV-curable systems

The effect of unsaturated polyester backbone composition on the properties of donor-acceptor-UV-cured coatings was explored. The polyesters were designed with similar molecular weights and levels of unsaturation, but with otherwise widely varying backbone compositions. UV-curable coatings were formulated with stoichiometric levels of triethylenglycol divinyl ether and a photoinitiator. The resulting coatings had a broad range of properties, which were found to correlate with the properties and compositions of the polyester backbone polymers. A relatively flexible backbone resulted in lower glass transition temperatures (T_g). The polymer T_g was found to influence the conversion of double bonds achieved during UV curing. Reaction kinetics were evaluated for the coating systems and the results confirmed that the T_g of the systems influenced the double bond conversion. Thermal stability and König pendulum hardness were also found to vary with the backbone composition of the constituent polyester.     

Effect of Silane Coupling Agents on Adhesion of Polybutadiene to Glass

The chosen silane coupling agents consist of a polybutadiene skeleton with  Si(CH₃)₂OCH₃ or  Si(OCH₃)₃ pendent groups hydrolyzable on the glass surface. Their number, and therefore the amount of potential bonds, can be varied. These modified polybutadiene polymers act as primer compatible with the polybutadiene coating to be deposited. The subsequent cross-linking of the double bonds of the silane primed surface with polybutadiene is initiated by benzoyl peroxide, creating chemical bonds between the solid support and its coating. The strength of the adhesion of polybutadiene to glass is measured by the 180° peel test and the values are compared with a non-modified glass surface.     

Synthesis and photovoltaic properties of polythiophene derivatives with side chains containing C60 end group

A donor–acceptor double‐cable polythiophene derivative ( PT‐F1 ) with side chain containing C₆₀ end group was synthesized, and characterized by infrared, UV‐vis absorption and photoluminescence (PL) spectroscopy, and electrochemical cyclic voltammetry. Cyclic voltammogram of PT‐F1 shows the oxidation peak of the polymer main chains and the reduction peaks of the C₆₀ end groups, indicating that there is no interaction between the polymer main chains and side chain C₆₀ groups on the ground state. The UV‐vis absorption spectrum of PT‐F1 film is red‐shifted in comparison with that of its chloroform solution. The PL spectrum of the polymer main chain was quenched by the C₆₀ pendant on the side chain. Polymer solar cell with the structure of ITO/PEDOT:PSS/ PT‐F1 /Ca/Al was fabricated. The power conversion efficiency of the device based on PT‐F1 reached 0.274% under the illumination of AM 1.5, 100 mW/cm². © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of nano‐TiO2 on MP‐25 resin

MP‐25 resin is a chlorine‐containing polymer widely used in coatings. The effects of two types of nano‐TiO₂ (P‐25 and RM301 LP) on MP‐25 were studied with saline immersion, UV irradiation, and electrochemical impedance spectroscopy. UV irradiation was evaluated in terms of gloss change and X‐ray photoelectron spectroscopy (XPS). The results indicate that, compared to pigment R‐930 TiO₂, P‐25 reduced the immersion resistance and accelerated UV aging of the MP‐25 coating, whereas RM301 LP showed the opposite effects. XPS analysis showed that MP‐25 resin degraded under UV irradiation via dechlorination and C? C bond breakage, similarly to poly(vinyl chloride), but RM301 LP could inhibit the aging of MP‐25 to a certain extent. A skin effect of oxygen and chlorine was identified in MP‐25 resin by XPS. RM301 LP could improve the impedance of the MP‐25 coating because of its excellent fill capacity. Hence, rutile nano‐TiO₂ RM301 LP represents an excellent additive for MP‐25 resin. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Soluble semi-conductive chelate polymers containing Cr(III) in the backbone: Synthesis, characterization, optical, electrochemical, and electrical properties

Soluble kinds of coordination polymers containing Cr(III) ion in the backbone were synthesized. Structures of the polymers were characterized by FT-IR, UV-vis, ¹H and ¹³C NMR, and size exclusion chromatography (SEC). Thermal degradation data were obtained by TG-DTA and DSC techniques. Cyclic voltammetry (CV) measurements were carried out and the HOMO-LUMO energy levels and electrochemical band gaps were calculated. Additionally, the optical band gaps (E_g) were determined by using UV-vis spectra of the materials. Electrical conductivity measurements of doped (with iodine) and undoped polymers related to temperature were carried out by four-point probe technique using a Keithley 2400 electrometer. Measurements were made by using the polymeric films deposited on ITO glass plate by dip-coating method. Also, absorption spectra of doped polymeric films were recorded by a single beam spectrophotometer showing that doping procedure causes shifting in absorption spectra. Their abilities of processing in gas sensors were also discussed. According to obtained results the synthesized chelate polymers are semi-conductors having polyconjugated structures. Also, P-2 is the most electro-conductive polymer among the synthesized, while P-1 is the most thermally stable one.     

Synthesis and characterization of azo‐based acrylate polymers for use as nonlinear optical materials

In this work, high molecular weight azo polymers were synthesized by incorporating the azo monomer into a base polymer through their reactive functional groups. Copolymers of methyl methacrylate and methacrylic acid (with varying concentrations of carboxylic acid group) were synthesized. These were then reacted with epoxy‐terminated azo molecule by carboxylic acid–epoxy reaction. The functionalized systems show excellent film homogeneity and optical clarity. The series of copolymers were characterized using FTIR, NMR, UV–vis spectrometry, gel permeation chromatography, elemental analysis, thermogravimetric analysis, and differential scanning calorimetry. The polymer films coated on ITO glass slides were poled and their order parameters were calculated to check the stability of oriented dipoles. Temporal stability, checked up to 120 h under ambient conditions, was found to be excellent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 425–431, 2007     

Microstructure and its relationship to deformation processes in amorphous polymer glasses

The microdeformation morphology of a number of vinyl polymers with bulky side chains (type I) and arylene polymers with flexible oxygen linkages (type II) was studied by electron microscopy. The polyarylenes crazed only near the glass transition while the polyvinyls exhibited a crazing regime that extended to liquid nitrogen temperatures. In addition significantly less plastic strain was localized in type II glass crazes relative to those in type I glasses. In compatible blends of polystyrene (PS) and 2,6-dimethyl poly(phenylene oxide) (2MPPO), ca. 30% 2MPPO was sufficient to induce a transition from type I to type II crazing behavior. Small amounts of PS suppressed the low-temperature 2MPPO β relaxation but enhanced the intermediate transition of 2MPPO at higher temperatures. Blending increased the conformational energy of the 2MPPO chain and improved interchain packing. The propensity for the polymer glass to form sharp shear bands at the expense of diffuse bands was increased by a decrease in the conformation energy of the polymer chain and an improvement in the glassy state packing.     

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.     

Poly(azomethine-imide)s containing siloxane moities: Optical,thermal, mechanical,and morphological properties

A new series of poly(azomethine-imide)s having siloxane moities in backbone was prepared using different dianhydrides.Thermal, optical, and morphological properties of these polymers were clarified. Also, bulky  CO and  CF₃ group effects and meta or para-substituted aldeyhde effects on the mentioned properties were evaluated. The structural characterization of poly(azomethine-imide)s was carried out using a FT-IR spectroscopy. The optical properties of the polymers were performed via an UV–Vis spectrophotometer. Optical band gap of the poly(imide)s containing azomethine was calculated between 2.20 and 2.33 eV. Thermal behavior of poly(azomethine-imide)s was also studied using TG-DTA, DSC, and DMA techniques. The onset degradation temperature and percentage char values of the polyimides were found in the range from 429 to 545 °C and 22 to 35%, respectively. Thermal stability results demonstrated that benzophenone bearing poly(azomethine-imide)s have higher onset temperature, percentage char, and the glass transition temperature than poly(azomethine-imide)s derived from hexafluoroisopropylidene. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48364.     

Synthesis and characterization of a novel electroactive polymer with oligoaniline and nitrile groups

By oxidative coupling polymerization approach, we have synthesized a novel electroactive polymer with alternating phenyl-capped aniline tetramer in the main chain and nitrile group in the side chain. The detailed characteristics of the as-synthesized polymer were systematically studied by Fourier-transform infrared (FTIR) spectra, nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC). UV–vis spectra were used to monitor the oxidation process of the polymer. Moreover, the electrochemical behavior of the polymer was explored by cyclic voltammogram (CV), showing that the intrinsic electroactivity of the oligoaniline was maintained in the polymer and two distinct reversible oxidative states were observed. The thermogravimetric analysis (TGA) indicated that the polymer possessed good thermal resistance due to the introduction of the rigid and polar nitrile groups in side chains. The reactivity of nitrile group provides the probability of modifying and functionalizing the polymer further, and creating a series of novel functional polymers.     

Electrosynthesis and spectroelectrochemical characterization of poly(3,4-dimethoxy-thiophene), poly(3,4-dipropyloxythiophene) and poly(3,4-dioctyloxythiophene) films

Poly(3,4-dialkoxythiophene) films with different length of alkyl chain (1,3 and 8 carbon atoms) were obtained on Pt and ITO electrodes from the monomer solutions in acetonitrile by cyclic voltammetry (CV). The properties of the resulting films were studied by electrochemical methods, UV-Vis, FTIR and NMR spectra. The CVs were correlated with differential cyclic voltabsorptograms (DCVA) recorded at the absorption maxima to explain the shape of the voltammograms of the polymers studied, dependent on the alkyl-chain length in alkoxy group. The presence of the zones of different crystallinity in the polymer film was postulated. Significant influence of the type of the solvent on asymmetry of the cyclic voltammograms for the polymer doping-undoping has been discussed in terms of the solvent interaction with radical cation (polaron) delocalized on the alkoxy side groups. The polaron delocalization was proved by ¹H-NMR spectra. Appearance of infrared activated vibrations (IRAVs) in the range 1500-600 cm⁻¹ and a characteristic electronic band at 3300 cm⁻¹ at the polarization potential +0.25 V versus Ag/Ag⁺ and their gradual changes upon further polymer oxidation were interpreted in terms of evolution of different charge carriers in lightly and heavily doped polymer.     

Chain walking copolymerization of ethylene with cyclopentene - Effect of ring incorporation on polymer chain topology

Chain walking ethylene copolymerizations with cyclopentene (CPE) as the ring-forming comonomer were carried out in this study to investigate the tuning of polyethylene chain topology via the unique strategy of ring incorporation. Four sets of polymers containing five-membered rings on the polymer backbone at various low contents (in the range of 0-7.5 mol%) were synthesized by controlling CPE feed concentration at four different ethylene pressure/temperature combinations (1 atm/15 °C, 1 atm/25 °C, 1 atm/35 °C, and 6 atm/25 °C, respectively) using a Pd-diimine catalyst, [(ArNC(Me)-(Me)CNAr)Pd(CH₃)(NCMe)]⁺SbF₆⁻ (Ar = 2,6-(iPr)₂C₆H₃). The polymers were characterized extensively using ¹³C nuclear magnetic resonance (NMR) spectroscopy, triple-detection gel permeation chromatography (GPC), and rheometry to elucidate the chain microstructures and study the effect of ring incorporation on polymer chain topology. It was found that CPE was incorporated in the copolymers primarily in the form of isolated cis-1,3 ring units, along with a small fraction in the form of isolated cis-1,2 ring units. Significant linearization of polymer chain topology was achieved with ring incorporation in each of the three sets of polymers synthesized at 1 atm on the basis of the incrementally raised intrinsic viscosity curves in the Mark-Houwink plot and the significantly enhanced zero-shear viscosity of the polymer melts with the increase of ring content despite the decreasing polymer molecular weight. For the set of polymers synthesized at 6 atm/25 °C, the effect of ring incorporation on polymer chain topology was negligible or weaker due to their linear chain topology resulting at this polymerization condition. The results obtained in this study support the proposed blocking effect of backbone-incorporated rings on catalyst chain walking, and demonstrate that effective tuning of polyethylene chain topology from hyperbranched to linear can be conveniently achieved via CPE incorporation while without changing ethylene pressure or polymerization temperature.     

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.     

Synthesis and antimicrobial activities of new water‐soluble bis‐quaternary ammonium methacrylate polymers

New methacrylate monomers containing pendant quaternary ammonium moieties based on 1,4‐diazabicyclo‐[2.2.2]‐octane (DABCO) were synthesized. The DABCO group contains either a butyl or a hexyl pendant group comprising the hydrophobic segment of the monomers and one tether group to the methacrylate moiety. The monomers were homopolymerized in water by using 2,2′‐azobis(2‐methylpropionamide) dihydrochloride (V‐50) as an initiator. The monomers and polymers were characterized by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), FTIR, and ¹³C‐NMR. The antimicrobial activities of the corresponding small molecules (bis‐quaternary ammonium monocarboxylates) and polymers were investigated against Staphylococcus aureus and Escherichia coli. Although the small molecules did not show any antimicrobial activity, the polymers were moderately effective against both Gram‐positive and Gram‐negative bacteria. The minimum inhibitory concentration (MIC) values of the polymers with butyl and hexyl hydrocarbon chains against S. aureus and E. coli were found to be 250 and 62.5 μg/mL, respectively. The minimum bactericidal concentration (MBC) value for the polymer with the butyl group was higher than 1 mg/mL, whereas the MBC value for the polymer with hexyl group was found to be 62.5 μg/mL. Thus, an increase of the alkyl chain length from 4 to 6 significantly increased the antimicrobial activity of the polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 635–642, 2004     

Synthesis and characterization of photoelectronic polymers containing triphenylamine moiety

Several polymers containing triphenylene moieties in main chain were synthesized by Knovenagel or Wittig condensations. The polymers were characterized by ¹H NMR, IR, GPC, TG, UV–vis, FL and CV. Results indicated that PNB, which was prepared from the polycondensation of 4,4′-dialdehyde-4″-n-butyltriphenylamine with 1,4-bis(triphenylphosphonionmethyl)benzene dibromide, is the most thermally stable one and that PNP, which was prepared from the polycondensation of 4,4′-dialdehyde-4″-n-butyltriphenylamine with p-phenylene diacetonitrile, is the most thermally instable one. The fluorescence quantum efficiency of PNB is 94.3%, which is a high value for optoelectronic polymer materials. All the polymers have a similar CV curve with a reversible oxidation peak and two reduction peaks except that PNB has a single reduction peak.     

Synthesis and physicochemical properties of new fatty (co)polyamides as potential UV powder coating

Partially or fully biosourced (co)polyamides have been prepared from commercial (11-aminoundecanoic acid, octadec-9-en-1,18-dioic acid, dodecan-1,12-diamine) and/or an original branched and unsaturated ((9Z)-octadecene-1,12-diamine) monomer. Undec-11-enoic acid was used as chain limiter in order to obtain controlled average number molecular weights around 7000 g mol⁻¹. By varying the relative composition of monomers and/or the amount of side chains and/or the amount of unsaturated repeating units, copolyamides exhibiting low glass transition temperatures ranging from −31 to 3 °C and low melting temperatures ranging from 60 to 143 °C have been obtained. The branched monomer was found to act as internal plasticizer. Coatings have been prepared from these polymer materials at their melting temperatures. The presence of carbon–carbon double bonds on the polymer backbone allowed their photocrosslinking in the presence of benzophenone. This UV curing enhanced the hardness of the obtained coatings. These polymers are therefore expected to be used as bio-based UV powder coatings for heat sensitive substrates.