Plasma polymerization of acetylene onto silica: an approach to control the distribution of silica in single elastomers and immiscible blends

Surface modification of silica by acetylene plasma polymerization is applied in order to improve the dispersion in and compatibility with single rubbers and their blends. Silica, used as a reinforcing filler for elastomers, is coated with a polyacetylene (PA) film under vacuum conditions. Water penetration measurements show a change in surface energy due to the PA‐film deposition. The weight loss measured by thermo‐gravimetric analysis (TGA) is higher for the PA‐coated silica compared to the untreated filler, confirming the deposition of the PA film on the silica surface. Time of flight‐secondary ion mass spectrometry (ToF‐SIMS) shows the well‐defined PA cluster peaks in the high mass region. Scanning electron microscopy (SEM) measurements show silica aggregates, coalesced by the coating with smooth and uniform surfaces, but without significant change in specific surface area. Elemental analysis by energy dispersive X‐ray spectroscopy (EDX) measurements also confirms the deposition of the polymeric film on the silica surface, as the carbon content is increased. The performance of single polymers and their incompatible blends based on S‐SBR and EPDM, filled with untreated, PA‐ and silane‐treated silica, is investigated by measurements of the bound rubber content, weight loss related to bound rubber, cure kinetics, reinforcement parameter, Payne effect, and mechanical properties. The PA‐ and silane‐modified silica‐filled pure S‐SBR and EPDM samples show a lower filler–filler networking compared to the unmodified silica‐filled elastomers. Decrease in the reinforcement parameter (α_F) for the plasma‐polymerized silica‐filled samples also proves a better dispersion compared to silane‐modified and untreated silica‐filled samples. On the other hand, the PA‐silica‐filled samples show a higher bound rubber content due to stronger filler–polymer interactions. Finally, the PA‐silica‐filled pure EPDM and S‐SBR/EPDM blends show high tensile strength and elongation at break values, considered to be the result of best dispersion and compatibilization with EPDM. Copyright © 2008 John Wiley & Sons, Ltd.     

Dependence of silica particle sizes on network chain lengths,silica contents,and catalyst concentrations in in situ‐reinforced polysiloxane elastomers

Poly(dimethylsiloxane) networks were prepared by tetrafunctionally end‐linking hydroxyl‐terminated chains with tetraethoxysilane (TEOS). Molecular composites were then prepared by in situ sol–gel reactions on additional TEOS swelled into the networks, resulting in the formation of reinforcing silica fillers within the host elastomers. The amount of filler generated generally increased linearly with an increase in the TEOS swelling ratio, as expected. The silica particles formed were examined by small‐angle X‐ray scattering. Of particular interest were the relationships between particle size and molecular weight M_c of the network chains (mesh sizes), amount of filler introduced, and catalyst concentration. Particle sizes were smallest for the smallest values of M_c, possibly demonstrating constraining effects from the very short network chains. At fixed M_c and filler concentrations, higher catalyst concentrations gave larger particles. Increase in filler concentration generally had little effect on particle size at low and high loadings, but markedly increased sizes at intermediate levels (10–20 wt %), presumably caused by coalescence of the scattering entities into considerably larger aggregates. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1421–1427, 1999     

The role of thiophosphoryl disulfide on the co‐cure of CR‐EPDM blends: effect of white fillers

Bis(diisopropyl) thiophosphoryl disulfide (DIPDIS) being a rubber accelerator has a definite role as a coupling agent in the silica filled polychloroprene rubber with ethylene propylene diene rubber (CR‐EPDM) blends. Diethylene glycol can further improve the beneficial effect of DIPDIS in silica filled CR‐EPDM blends. Two‐stage vulcanization technique further improves the physical properties of silica filled CR‐EPDM blends. The results have been compared with non‐reinforcing calcium carbonate filled systems. Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the silica filled CR‐EPDM blend vulcanizates obtained from this two‐stage process. Copyright © 2004 John Wiley & Sons, Ltd.     

Preparation and properties of high molecular weight polyethoxysiloxanes stable to self‐condensation by acid‐catalyzed hydrolytic polycondensation of tetraethoxysilane

The acid‐catalyzed controlled hydrolytic polycondensation of tetraethoxysilane (TEOS) provided polyethoxysiloxanes with weight‐average molecular weights of 2300–11,700, which depended on the reaction molar ratios of the water, catalyst, and solvent to TEOS. They were soluble in common organic solvents and stable to self‐condensation and were characterized with high silica contents of up to 67%. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2250–2255, 2003     

Filler‐polymer interactions of styrene and butadiene units in silica‐filled styrene–butadiene rubber compounds

Styrene–butadiene rubber (SBR) is a copolymer of styrene and butadiene, and the butadiene unit is composed of cis‐1,4‐, trans‐1,4‐, and 1,2‐components. Filler‐polymer interactions of each component of SBR in silica‐filled SBR compounds were examined by microstructure analysis of the bound and unbound rubbers. The composition ratio of butadiene and styrene units (butadiene/styrene) of the bound rubber was higher than that of the compounded rubber. Of the butadiene units, the 1,2‐component of the bound rubber was more abundant than the cis‐1,4‐ and trans‐1,4‐components. The filler‐polymer interaction of the butadiene unit with silica was stronger than that of the styrene unit, and the interaction of the 1,2‐component was stronger as compared with the others. The butadiene–styrene ratio of the bound rubber of the compounds containing the silane coupling agent was lower than for the compounds without the silane. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 577–584, 2004     

New architecture of supported metallocene catalysts for alkene polymerization

We report the synthesis of a supported metallocene catalyst that exhibits the same activity as a homogeneous catalyst for ethylene polymerization reactions. The key to this new catalytic system is a hybrid organic–inorganic polymer obtained by the cocondensation of an organotrialkoxysilane (OTAS; 40 mol %) with tetraethoxysilane (TEOS; 60 mol %). The particular organic group of OTAS enabled us to avoid gelation when the hydrolytic condensation was performed with a thermal cycle attaining 150 °C. The resulting product [soluble functionalized silica (SFS)] was a glass at room temperature that was soluble in several organic solvents such as tetrahydrofuran and toluene. The ²⁹Si NMR spectrum of SFS showed that the OTAS units were fully condensed (T₃ species), whereas the TEOS units were mainly present as tricondensed (Q₃) and tetracondensed (Q₄) units. SFS was grafted onto activated silica through a reaction of silanol groups. The metallocene [(nBuCp)₂ZrCl₂] was covalently bonded to the SFS‐modified support. The polymerization of ethylene was carried out in toluene in the presence of methylaluminoxane. The activity of the supported catalyst was similar to that of the metallocene catalyst in solution. The simplest explanation accounting for this fact is that most of the metallocene was grafted to SFS species issuing from the surface of the support through a reaction with their silanol groups. This improved the accessibility of the monomer to the reaction sites. Specific interactions of the metallocene species with neighboring organic branches of SFS might also affect the catalytic activity. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5480–5486, 2007     

Hydrogel synthesis by aqueous Diels‐Alder reaction between furan modified methacrylate and polyetheramine‐based bismaleimides

A simple method for preparing cross‐linked hydrogels in an aqueous medium is investigated using Diels‐Alder (DA) “click” reaction, without employing a catalyst. A polymeric diene is first synthesized by the functionalization of poly(2‐aminoethyl methacrylate) hydrochloride with furfural. Suited bisdienophiles are prepared by modification of Jeffamine^® ED of different molecular weights with maleic anhydride. Both precursors of the DA coupling are thoroughly characterized before their reactions. The ensuing hydrogels are analyzed in terms of their microstructure, swelling, and rheological behavior, as a function of the reaction conditions. The influence of the molecular weight of the cross‐linker and the furan‐to‐maleimide ratio on the final properties of the hydrogels were also investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 699–708     

Highly active bifunctional cobalt‐salen complexes for the synthesis of poly(ester‐block‐carbonate) copolymer via terpolymerization of carbon dioxide,propylene oxide,and norbornene anhydride isomer: Roles of anhydride conformation consideration

This article describes an efficient synthetic route of defined reactive polyester‐block‐polycarbonate copolymers, utilizing a bifunctional SalenCoNO₃ complex as catalyst for the single‐step terpolymerization of norbornene anhydride (NA), propylene oxide, and carbon dioxide. The geometric isomer of NA plays an important role in polymerization efficacy and the resulting polymer microstructure, including carbonate content, sequence isomer of polycarbonate moiety, and molecular weight. A hydroxyl‐functionalized polyester–polycarbonate block copolymer was synthesized by a thiol‐ene reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 789–795     

Air‐stable and recoverable catalyst for copper‐catalyzed controlled/living radical polymerization of styrene; In situ generation of Cu(I) species via electron transfer reaction

Copper‐catalyzed controlled/living radical polymerization (LRP) of styrene (St) was conducted using the silica gel‐supported CuCl₂/N,N,N′,N′,N″‐pentamethyldiethylenetriamine (SG‐CuCl₂/PMDETA) complex as catalyst at 110 °C in the presence of a definite amount of air. This novel approach is based on in situ generation and regeneration of Cu(I) via electron transfer reaction between phenols and Cu(II). Sodium phenoxide or p‐methoxyphenol was used as a reducing agent of Cu(II) complexes in LRP. The number–average molecular weight, M_n,GPC, increases linearly with monomer conversion and agrees well with the theoretical values up to 85% conversion The molecular weight distribution, M_w/M_n, decreases as the conversion increases and reaches values below 1.2. The catalyst was recovered in aerobic condition and reused in copper‐catalyzed LRP of St. For the second run, the number–average molecular weights increased with monomer conversion and the polydispersities decreased as the polymerization proceeded and reached to the value <1.3 at 81% conversion. The recycled catalyst retained 90% of its original activity in the subsequent polymerization. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 77–87, 2006     

Synthesis of alkaline‐developable,photosensitive hyperbranched polyimides through the reaction of carboxylic acid dianhydrides and trisamines

Hyperbranched polyimides (HBPI)s with high glass‐transition temperatures and excellent thermal stability were synthesized through the reaction of commercially available carboxylic acid dianhydrides with tris[4‐(4‐aminophenoxy)phenyl]ethane (TAPE). In particular, hyperbranched polyimide HBPI(TAPE‐DSDA), prepared through the reaction of TAPE with 3,3′,4,4′‐diphenylsulfonetetracarboxylic dianhydride (DSDA), showed higher thermal stability and good solubility. Furthermore, alkaline‐developable, photosensitive HBPI(TAPE‐DSDA)‐MA‐CA was prepared through the reaction of HBPI(TAPE‐DSDA) with glycidyl methacrylate with tetrabutylammonium bromide as a catalyst in N‐methyl‐2‐pyrrolidinone (NMP) followed by the addition reaction of cis‐1,2,3,6‐tetrahydrophthalic anhydride with triphenylphosphine as a catalyst in NMP. The glass‐transition temperatures of HBPI(TAPE‐DSDA)‐MA‐CA were greater than 300 °C. A resist composed of 74 wt % HBPI(TAPE‐DSDA)‐MA‐CA, 22.2 wt % trimethylpropane triacrylate, and 3.8 wt % Irgacure 907 as a photoinitiator achieved a resolution of a 55‐μm line pattern and a 275‐μm space pattern by UV irradiation (1000 mJ/cm²). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3697–3707, 2004     

Radiochemical aging of ethylene–propylene–diene monomer elastomers. I. Mechanism of degradation under inert atmosphere

This article is devoted to the study of electron‐beam‐induced degradation under argon atmosphere of an ethylene–propylene–diene monomer (EPDM, based on 5‐ethylidene 2‐norbornene) and an ethylene–propylene rubber (EPR) containing the same molar ratio of ethylene/propylene. The chemical structure modifications of polymeric samples were analyzed by ultraviolet–visible and IR spectroscopies. Crosslinking reactions were deduced by measuring the changes in gel fraction and the degree of swelling in n‐heptane. Irradiation of EPDM and EPR created trans‐vinylene, vinyl, vinylidene, and dienic‐type unsaturations. The radiochemical yields for unsaturation formations in EPDM and EPR were similar. Degradation also involved crosslinking and the production of molecular hydrogen. The comparison between EPDM and EPR showed that the diene (in which a double bond is consumed with a high radiochemical yield) contributes to the increase in rate and intermolecular bridges density. Mechanisms are proposed to account for the main routes of EPDM degradation. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1239–1248, 2004     

A rheological and spectroscopic study on the kinetics of self‐healing in a single‐component diels–alder copolymer and its underlying chemical reaction

In this work, pendant groups with both furan and maleimide moieties were incorporated into a polymethacrylate copolymer with lauryl methacrylate as comonomer to yield a one‐system Diels–Alder (DA) polymer. A combined Fourier transform infrared (FTIR) spectroscopy and rheological study was performed to quantify the extent of the reversible DA reaction and the resulting changes in mechanical properties of the polymer. The kinetics of the retro‐Diels–Alder (rDA) reaction was studied at different temperatures to determine an enthalpy of activation. Control polymers with only one functional moiety, that is, the furan or maleimide, were also synthesized to study the differences in viscoelastic behavior and the absence of self‐healing. Microscratch tests were performed to obtain information about the disappearance of well‐defined intentional surface scratches under different healing conditions. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1669–1675     

Synthesis of peroxide‐curable butyl rubber via suzuki–miyaura coupling of halogenated butyl rubber with 4‐vinylphenylboronic acid

The Suzuki–Miyaura coupling reaction of brominated butyl rubber (BIIR) and/or chlorinated butyl rubber with a mixture of 4‐vinylphenylboronic acid and phenylboronic acid was carried out in THF under various conditions using a di‐μ‐chlorobis [5‐hydroxy‐2‐[1‐(hydroxyimino‐κN)ethyl]phenylκC] palladium(II) dimer, which is a type of cyclopalladated complex, as a catalyst. When BIIR and a small amount (Pd/Br ≈ 1/1000) of complex were used as the substrate and catalyst, respectively, a 4‐vinylphenyl and phenyl group could be introduced to butyl rubber in a high yield. Isomerization of the exo carbon–carbon double bond in BIIR was observed during the coupling reaction to give a cis and trans endo structure. The peroxide curing behavior of the resulting polymer at 170 °C indicated that the polymer could be cured by dicumyl peroxide, and the maximum torque of the resulting material, which reflects the crosslink density, was controllable by the composition of the boronic acids used. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of multifunctional polymer containing Ni‐Pd NPs via thiol‐ene reaction for one‐pot cascade reactions

Recently, acid–base bifunctional catalysts have been considered due to their abilities, such as the simultaneous activation of electrophilic and nucleophilic species and their high importance in organic syntheses. However, the synthesis of acid–base catalysts is problematic due to the neutralization of acidic and basic groups. This work reports a facial approach to solve this problem via the synthesis of a novel bifunctional polymer using inexpensive materials and easy methods. In this way, at the first step, heterogeneous poly (styrene sulfonic acid‐n‐vinylimidazole) containing pentaerythritol tetra‐(3‐mercaptopropionate) (PETMP) and trimethylolpropane trimethacrylate (TMPTMA) cross‐linkers were synthesized in the pores of a mesoporous silica structure using click reaction as a novel bifunctional acid–base catalyst. After that, Ni‐Pd nanoparticles supported on poly (styrenesulfonic acid‐n‐vinylimidazole)/KIT‐6 as a novel trifunctional heterogeneous acid–base‐metal catalyst was prepared. The prepared catalysts were characterized by various techniques like FT‐IR, TGA, ICP‐AES, DRS‐UV, TEM, FE‐SEM, EDS‐Mapping, and XRD. The synthesized catalysts were efficiently used as bifunctional/trifunctional catalysts for one‐pot, deacetalization‐Knoevenagel condensation and one‐pot, three‐step and a sequential reaction containing deacetalization‐Knoevenagel condensation‐reduction reaction. It is important to note that the synthesized catalyst showing high chemo‐selectivity for the reduction of nitro group, alkenyl double bond and ester group in the presence of nitrile. Moreover, it was found that the different nanoparticles including Ni, Pd, and alloyed Ni‐Pd showing different chemo‐selectivity and catalytic activity in the reaction.     

Synthesis of statistical glycidyl methacrylate‐n‐vinyl pyrrolidone copolymers and their reaction with naproxen

Free‐radical copolymerization of glycidyl methacrylate (GMA) with N‐vinylpyrrolidone (VPD) was carried out at 50 °C using 3.0 mol · L^?1 of N,N′‐dimethylformamide solution and 9.0 · 10^?3 mol · L^?1 of 2,2′‐azobisisobutyronitrile as an initiator. The modification reaction of GMA‐VPD copolymers with a model bioactive carboxylic acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen), was studied in the homogeneous phase using basic catalysts. The influence of the type of catalyst and the GMA content was evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1192–1199, 2002     

Preparation of poly(methyl acrylate‐co‐itaconic anhydride)/SiO2 hybrid materials via the sol–gel process—The effect of the coupling agent,inorganic content,and nature of the catalyst

Transparent poly(methyl acrylate‐co‐itaconic anhydride)/SiO₂ hybrid materials were prepared from methyl acrylate‐itaconic anhydride copolymer and tetraethoxysilane (TEOS) with the coupling agent (3‐aminopropyl)triethoxysilane (APTES) via a sol–gel process. The covalent bonds between the organic and inorganic phases were introduced by the in situ aminolysis of the itaconic anhydride units with APTES forming a copolymer bearing a triethoxysilyl group. These groups subsequently were hydrolyzed with TEOS and allowed to form a network. These reactions were monitored by Fourier transform infrared analysis. The amount of APTES had a dramatic influence on the gel time and sol fraction. The effect of APTES, the inorganic content, and the nature of the catalyst on the thermal properties and morphology of the hybrid materials were studied by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 321–328, 2000     

Flame‐retardant epoxy resins: An approach from organic–inorganic hybrid nanocomposites

Phosphorus‐containing epoxy‐based epoxy–silica hybrid materials with a nanostructure were obtained from bis(3‐glycidyloxy)phenylphosphine oxide, diaminodiphenylmethane, and tetraethoxysilane in the presence of the catalyst p‐toluenesulfonic acid via an in situ sol–gel process. The silica formed on a nanometer scale in the epoxy resin was characterized with Fourier transform infrared, NMR, and scanning electron microscopy. The glass‐transition temperatures of the hybrid epoxy resins increased with the silica content. The nanometer‐scale silica showed an enhancement effect of improving the flame‐retardant properties of the epoxy resins. The phosphorus–silica synergistic effect on the limited oxygen index (LOI) enhancement was also observed with a high LOI value of 44.5. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 986–996, 2001     

Synthesis of novel diene polymer via friedel–crafts‐type reaction of polybutadiene with aromatic compounds

This study describes a novel and facile synthesis strategy for a styrene‐butadiene rubber (SBR)‐like polymer via Friedel–Crafts‐type reaction between aromatic compounds and polybutadiene using an aluminum chloride as a catalyst. Although gelation was induced by a reaction of a generated carbocation with olefins in other polybutadiene chains in benzene and toluene because of their low electron densities on their rings, anisole with a higher electron density reacted with the polybutadiene carbocation efficiently. The introduction ratio of anisole increased as the reaction proceeded, and the obtained polymer, BRAN polymer, contained 15% anisoles for olefins in the polybutadiene in 4 h at 80 °C as estimated by ¹H NMR analysis. The glass‐transition temperature (T_g) of the BRAN polymer also increased with anisole content (T_g ~?50 °C when anisole contents 20%). The vulcanizate containing the BRAN polymer showed higher mechanical properties compared to samples using other matrix polymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 841–847     

Effects of the reaction parameters on the properties of thermosensitive poly(N‐isopropylacrylamide) microspheres prepared by precipitation and dispersion polymerization

Poly(N‐isopropylacrylamide) (PNIPAAm)‐based microspheres were prepared by precipitation and dispersion polymerization. The effects of several reaction parameters, such as the type and concentration of the crosslinker (N,N′‐methylenebisacrylamide or ethylene dimethacrylate), medium polarity, concentration of the monomer and initiator, and polymerization temperature, on the properties were examined. The hydrogel microspheres were characterized in terms of their chemical structure, size and size distribution, and morphological and temperature‐induced swelling properties. A decrease in the particle size was observed with increasing polarity of the reaction medium or increasing concentration of poly(N‐vinylpyrrolidone) as a stabilizer in the dispersion polymerization. The higher the content was of the crosslinking agent, the lower the swelling ratio was. Too much crosslinker gave unstable dispersions. Although the solvency of the precipitation polymerization mixture controlled the PNIPAAm microsphere size in the range of 0.2–1 μm, a micrometer range was obtained in the Shellvis 50 and Kraton G 1650 stabilized dispersion polymerizations of N‐isopropylacrylamide in toluene/heptane. Typically, the particles had fairly narrow size distributions. Copolymerization with the functional glycidyl methacrylate monomer afforded microspheres with reactive oxirane groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 968–982, 2006     

Two‐dimensional chromatography of complex polymers. IV. Analysis of the grafting reaction of methyl methacrylate onto polybutadiene

The grafting reaction of methyl methacrylate onto polybutadiene (PB) was investigated with different chromatographic techniques, including high‐performance liquid chromatography (HPLC) and online coupled two‐dimensional liquid chromatography. As a result of the grafting reaction, a complex mixture of nongrafted PB, the graft copolymer PB‐g‐PMMA [where PMMA is poly(methyl methacrylate)], and the PMMA homopolymer was formed. The complete separation of all the products of the grafting reaction was achieved with gradient HPLC. By the combination of gradient HPLC and size exclusion chromatography in a fully automated two‐dimensional chromatography setup, the complex distributions of the chemical composition and molar mass were fingerprinted simultaneously. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3143–3148, 2003