Syntheses and characterizations of new copolymers of vinylidene cyanide with para substituted α acetoxystyrenes

Summary Vinylidene cyanide has been copolymerized in solution by radical reaction with equal initial mole fraction of para substituted acetoxystyrenes. The copolymers have been characterized by means of DSC, TGA and GPC. These products are stable up to 220° and have no visible glass transition temperature. The microstructure of these new copolymers has been studied by ¹³CNMR; they have an alternating structure and monomers units are arranged in head-to-tail placements.     

Construction of inter-chain polymers and the investigation into Friedel–Crafts alkylation of styrene–acrylonitrile copolymers with chloroprene rubber and characterization

In this study, the Friedel–Crafts alkylation was realized in a solvent free processing of styrene–acrylonitrile copolymers/chloroprene rubber (SAN/CR) molten blending which contributes the formation of SAN-co-CR co-polymers and improved compatibility between SAN and CR. The properties of several Lewis acid compounds were tested as catalysts among which AlCl₃ was the most efficient. The effects of blending temperature and time on the co-polymer formation in situ were also investigated. The methodology of weighing and Fourier transform infrared analyses indicated that the reaction degree increases with increasing blending temperature and time in the ranges of this study. The micro-structures and reaction mechanisms of the resulted SAN-co-CR polymers and morphological structures of SAN/CR/AlCl₃ blends were characterized as well by differential scanning calorimetry, FT-IR spectra, GPC and scanning electron microscopy. The results showed that the inter-facial reactions between SAN and CR have been effectively improved. Moreover, the inter-chain structure of SAN-co-CR co-polymers was proposed which is different from general grafting or blocking co-polymers.     

Polymerization under magnetic field—II. Radical polymerization of acrylonitrile,styrene and methyl methacrylate

Radical polymerization of acrylonitrile (AN), methyl methacrylate (MMA) and styrene (S) has been studied under magnetic field (MF) using an AIBN initiator. The effect of MF is observed on the polymerization of AN and not on MMA and styrene. This may be due to the heterogeneous polymerization of AN (occlusion theory). The MF increases the rate of AN polymerization and polymer (PAN) yield. The overall activation energy is not influenced by the MF; however, the MF helps to reduce the activation entropy of polymerization. The influence of MF alters the structure and properties of the polyacrylonitrile (PAN). The molecular weight (MW) of PAN prepared under MF is higher and the molecular weight distribution (MWD) is narrower than those obtained without MF. The syndiotactic stereoregularity and crystallinity of such PAN polymer is higher than that obtained without application of MF. Magnetic field enhances the thermostability and the dielectric property of PAN.     

Synthesis and characterization of side-chain oxazoline–methyl methacrylate copolymers bearing azo-dye

We synthesized new polymeric structures by attaching a side-chain azo-moiety on poly(oxazoline) and poly(oxazoline-co-methyl methacrylate)s. For the polymer analogous transformation, we took advantage of the highly effective ring-opening addition of carboxyl group to the oxazoline cycle. The comonomers feed ratio allowed us to control the composition of the products while the kinetic treatment, employing an integral method, revealed a statistical copolymerization tendency of 2-isopropenyl-2-oxazoline with methyl methacrylate in acetonitrile at 70 °C. The elemental analysis and ¹H NMR spectroscopy provided almost identical composition data for both the substrates and the side-chain copolymers. The UV spectroscopy sustained the quantitative addition of 4-(4-hydroxy-3,5-dimethylphenylazo)benzoic acid to the oxazoline rings. Both the unmodified copolymers and the coloured ones exhibited good thermal stabilities, up to 371 °C and 302 °C, respectively. The glass transition temperatures ranged from 141.5 to 177.5 °C and from 153.8 to 200.9 °C for the substrates and for the modified copolymers, respectively. Preliminary investigations showed fluorescence activity for all copolymers bearing azo-moieties.     

Syntheses and characterizations of copolymers of dicyanoquinone methides with α-acetoxystyrenes

Summary 7,7-Dicyanoquinone methides (1a-b) copolymerized spontaneously with substituted -acetoxystyrenes (2a-b) in benzene at 60 °C to give alternating copolymers (poly(1a-b-co-2a-b)) with the molecular weights of 8–60×10⁴ in 42–66% yields. When these copolymers were heated under nitrogen, they eliminated acetic acid quantitatively at around 200 °C to be converted to the copolymers (poly(3a-d)) with olefinic bonds, which were characterized by infrared and nuclear magnetic resonance spectroscopy. Alternating copolymers and the corresponding copolymers with olefinic bonds were amorphous, and capable of being cast from their chloroform solutions into transparent, tough films.     

Polycarboxylate superplasticizers of acrylic acid–isobutylene polyethylene glycol copolymers: monomer reactivity ratios,copolymerization behavior and performance

Acrylic acid–isobutylene polyethylene glycol (AA-TPEG) copolymers are typical of polycarboxylate superplasticizers (PCEs). AA-TPEG copolymers are prepared via free-radical polymerization with potassium persulfate as the initiator. The obtained copolymers were characterized by gel permeation chromatography (GPC) and infrared spectra (FTIR). The GPC method can break through the former limitations of the instruments and receive instantaneous unreacted and instantaneous monomer concentrations and not the initial monomer feeds. Since TPEG monomer is highly bulky, the common calculation methods for determining monomer reactivity ratios in copolymerization based on terminal copolymerization equation are not suitable. However, this study created non-linear least squares curve fitting of terminal copolymerization equation (NLLSQ-T) and penultimate copolymerization equation (NLLSQ-P) methods, which used Python’s NumPy, SciPy, and SymPy libraries to generate code and did numerical computations, bringing greater accuracy of monomer reactivity ratios. The monomer reactivity ratios were calculated with Fineman–Ross, Kelen–Tüdös, YBR, NLLSQ-T, and NLLSQ-P methods and found to be r _AA = 10.888, r′ _AA = 1.131, r _TPEG = 0.012, and r′ _TPEG = 0.042 for AA-TPEG copolymers. Moreover, this study also explored specific copolymerization behavior of similar structure of copolymers with steric hindrance under penultimate copolymerization equation, such as dependence of the mole fractions in the copolymer on the mole fractions of unreacted monomers in solution, variation of copolymer compositions with conversion and sequence length distribution. The fluidity and flow loss of pastes containing PCEs were investigated, and the appropriate PCEs dosages resulted in a better workability of cement pastes.     

Influence of solubility parameter difference between monomer and porogen on structures of poly (acrylonitrile–styrene-divinylbenzene) resins

In this work, the acrylonitrile (AN)-styrene (St)-divinylbenzene (DVB) resin was synthesized via suspension polymerization in the presence of inert porogens as diluent. The relationship of the solubility parameter (SP) of the materials and the porous properties of the resin was investigated. These porous spherical resin particles (0.25–0.84 mm) can be used as precursors of amidoxime resin which has a high metal ion chelating efficiency. The results showed that the porous properties (surface area and mean pore width) of the resin changed with variation in the compatibility between monomers and porogens. According to the the BET theory to N₂ sorption and scanning electron microscopy (SEM), the specific surface area of the obtained beads was strongly dependent on the compatibility of the components of the system and achieved values from 3.3 to 66.8 m²/g. The surface area of the terpolymer beads was found to rise with a decrease in the content of acrylonitrile or an increase in the SP of the porogens. However, the variation of the pore size was just the opposite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46979.     

Microstructure and property of porous mullites with a whiskers framework obtained by a sol–gel process

Porous mullites with a whiskers framework and high porosities were fabricated by the reaction sintering (1100 to 1600 °C, 1 h, in an airtight container) of an aerogel block shaped by the sol–gel transition of a mullite precursor composed of SiO₂ sol, Al₂O₃ and AlF₃ powders (as reaction catalyst). The effect of heating temperatures on porosity, whisker formation, microstructure feature and compressive strength of the porous mullites was determined by XRD, SEM and compressive test. The results indicate that after heating at temperatures from 1100 to 1600 °C, the porosities of the mullites varied within the range of 84.1–80.2%. The whiskers in the framework well lap-jointed each other to form the large space and became elongated and smooth at high temperatures due to the accelerated vapor–solid reaction rate. A maximum compressive strength of 16.1 MPa was obtained for the whiskers framework heated at 1600 °C; this strength was attributed to the strong bonding among the smooth whiskers.     

Synthesis of a silicone containing allylic monomer and its uses in the waterborne polyurethane/vinyl acetate–acrylic hybrid emulsion copolymers

A new silicone containing allylic monomer, allyl 3-(triethoxysilyl) propyl carbamate (ATESPC), based on (3-isocyanatopropyl) triethoxysilane (ICPTES) and allyl alcohol (AAL) has been synthesized for formulation of waterborne polyurethane (WPU). Then a series of new siliconized WPU, vinyl acetate (VAc)/2-ethylhexylacrylate (2-EHA) and ATESPC hybrid latexes P(VAc-2-EHA)/PU/Si have been successfully synthesized by the emulsion copolymerization in the presence of a WPU dispersion by using potassium persulfate (KPS) as an initiator. The WPU dispersion has been synthesized by a polyaddition reaction of hexamethylene diisocyanate (HMDI), on polypropylene glycol (PPG-1000) and dimethylol propionic acid (DMPA) as chain extender. The NCO chain ends being reacted with water (which act as a further chain extender producing some urea bonds). Films were obtained for different hybrid latexes of various compositions. The resulted monomer characterized by Fourier transformer infrared spectroscopy (FTIR), proton (¹H NMR), and carbon (¹³C NMR) nuclear magnetic resonance spectroscopes, respectively. The copolymers also were characterized by using Fourier transform infrared spectroscopy (FT-IR). Thermal properties of the copolymers were studied by using thermogravimetric analysis (TGA) and dynamic mechanical thermal analysis (DMTA). The morphology of copolymers was investigated by scanning electron microscopy (SEM) and then the effects of silicone concentrations on the water absorption ratio, was examined.     

Ionic liquids as co-solvents for zwitterionic copolymers and the preparation of poly(vinylidene fluoride) blend membranes with dominated β-phase crystals

A new series of green solvents that constituted with ionic liquids (ILs) and dimethyl acetamide (DMAc) were developed as good solvents for zwitterionic copolymers, and the dissolutions of amphiphilic copolymers carrying carboxylbetaine and sulfonatebetaine in these new solvents were studied. It was determined that the commonly found ILs such as 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF₄), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF₆) and many others were all effective co-solvents for zwitterionic copolymer with carboxylbetaine groups. However, the 1-methylimidazolium trifluoromethanesulfonic ([MIM]CF₃SO₃) instead of the [BMIM]BF₄ was proved as an effective co-solvent for the copolymer carrying sulfonatebetaine units. These newly designed mix-solvents were also good solvents for poly(vinylidene fluoride) (PVDF) and their influences on the crystallization as well as the formation of PVDF membranes were investigated. Our results had demonstrated that blend membranes with zwitterionic additives could be facilely prepared with many new solvent candidates.     

Nonisothermal melt-crystallization kinetics of isotactic polypropylene synthesized with a metallocene catalyst and compounded with different quantities of an α nucleator

The nonisothermal crystallization kinetics of a metallocene-made isotactic polypropylene (m-iPP) and its compounds with 0.1 wt % and 0.3 wt % of a sorbitol derivative [1,3:2,4-bis(3,4-dimethylbenzylidene)sorbitol (DMDBS); an α nucleator] were investigated by differential scanning calorimetry at different cooling rates from the melt. The nucleation efficiency was proved by a significant increase in the crystallization temperatures (accompanied by a slight augmentation of the degree of crystallinity and a decrease in the crystal sizes). This increase in the crystallization temperatures led to higher amounts of fractional content in the γ polymorph, even though DMDBS was supposed to be a nucleator for the α form. The Avrami and Ozawa methods effectively described only the early stage of crystallization, whereas a combined Avrami–Ozawa method was valid for the whole crystallization process. The values of the exponent for this method decreased for nucleated samples in the later stage of crystallization, especially in the case of m-iPP with 0.3 wt % DMDBS added (m-iPP03). The activation energy of the process and the surface free energy were also estimated. The production of considerable proportions of the γ polymorph in m-iPP03 corresponded to higher values of the activation energy and lower values of the surface free energy. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Microstructure analysis and thermal properties of l-lactide/?-caprolactone copolymers obtained with magnesium octoate

A series of copolymers with various compositions were prepared by the ring opening copolymerization of l-lactide (l-LA) and ?-caprolactone (?-CL) using nontoxic magnesium octoate as a catalyst in bulk. The copolymerization process and the influence of transesterification on the chain microstructure were examined by ¹H and ¹³C NMR. A tapered block or gradient copolymer is expected to be formed on the basis of the reactivity difference between l-LA and ?-CL. Two modes of transesterification occurred and played an important role in the redistribution of comonomer sequences but not a completely random distribution. The CLC sequence formed by the second mode of transesterification was observed at the end of reaction. The coefficient of the second mode of transesterification (T_II) increased as the feed mole fraction of ?-CL increased. In terms of the overall feed compositions, the L_LL^r values of lactidyl sequences calculated from the reactivity ratio exceeded the L_LL^e values determined from the product, however, the L_C^r values of caproyl sequences were identical or shorter than the L_C^e values. The thermal properties and crystallinities of the obtained copolymers were investigated by DSC and WAXD. The thermal properties and crystallinities depend on both the composition and the chain microstructure. The l-LA/?-CL copolymer with intermediate composition exhibited some blocky character by DSC. Only single T_g was observed for each copolymer and in agreement with the calculated value from Fox equation, indicating that the amorphous region of the copolymers is miscible. The obtained copolymers can best be described as random copolymers with more or less blocky chain structure.     

Synthesis of cardanol-based phthalonitrile monomer and its copolymerization with phenol–aniline-based benzoxazine

The cardanol-based phthalonitrile (PN) monomer was successfully produced via the nucleophilic substitution reaction of cardanol with 4-nitrophthalonitrile in potassium carbonate media. The conventional methods were employed to predict the chemical structure. The influence of long alkyl chains of cardanol was observed on the thermomechanical properties, recorded values were much below than the poly(Baph) standards. However, the thermal stabilities were recorded in good agreement to PN resin values. Furthermore, the 100 kGy dose of Co⁶⁰ irradiation does not show any remarkable changes in the studied properties. The copolymers from P-a benzoxazine and cardanol-based PN (CPN) on the different wt % blending were prepared. The curing behavior and mechanism of the monomer blends were analyzed. The curing of CPN was improved in the presence of active hydrogen produced from the P-a polymerization. The T _g and thermal properties of the copolymer were much better than the neat poly(P-a). © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47505.     

Magnetite nanoparticles stabilized with polymeric bilayer of poly(ethylene glycol) methyl ether-poly(?-caprolactone) copolymers

In this work, we report a synthetic method of water dispersible magnetite nanoparticles having oleic acid and poly(ethylene glycol) methyl ether-poly(?-caprolactone) (mPEG-PCL) amphiphilic block copolymer as polymeric stabilizers. The particles were prepared by coprecipitation of Fe(II) and Fe(III) in NH₄OH and had bilayer surface with hydrophobic inner layer and hydrophilic corona. mPEG-PCL copolymer was synthesized by a ring-opening polymerization of ?-caprolactone using mPEG as a macroinitiator in the presence of stannous octoate catalyst. FTIR and thermogravimetric analysis (TGA) indicated the presence of the copolymer on the particle surface. Roles of reaction parameters, such as stabilizer concentrations and time of ultrasonicating treatment, on percent of magnetite in the complex and its magnetic properties were investigated. Transmission electron microscopy (TEM) showed the average particle size about 9.0 ± 1.1 nm in diameter. Vibrating sample magnetometry (VSM) measurement indicated that the magnetite nanoparticles were superparamagnetic at room temperature. Approximately 6.8 ± 0.5% of indomethacin model drug (68 μg/mg of magnetite) was effectively entrapped on the particles.     

Blends of photovoltaic-grade ethylene–vinylacetate copolymers and low-density ethylene–octene copolymers,their morphology and their thermal,mechanical, and rheological properties

Blends of photovoltaic-grade ethylene–vinyl acetate copolymer (EVA), defined by high VA-content and low crystallinity, and low-density ethylene–octene copolymer (EO) have been investigated with regard to their processing, thermal and mechanical properties as well as their morphology. It was found that the amount of EO in the blend has a strong influence on the shear thinning behavior, melt viscosity and therefore the required extrusion temperature and resulting ability to incorporate temperature-sensitive additives like a peroxidic crosslinking agent. A phase separated morphology was found for all blend compositions, though partial miscibility leading to co-crystallization was observed for EVA rich blends. EO rich blends show lower glass transition and higher melting point compared to neat EVA and exhibit higher elastic modulus at elevated temperatures as well as greater elongation at break during tensile testing while the light transmission is diminished. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47714.     

Graft copolymers of poly(methyl methacrylate) and polyamide-6 via in situ anionic polymerization of ε-caprolactam and their properties

Graft copolymers of poly(methyl methacrylate) and polyamide-6 (PMMA-g–PA6) were investigated via in situ anionic polymerization of ε-caprolactam, using PMMA precursors with N-carbamated caprolactam pendants (PMMA–CCL) as macroactivators and sodium caprolactamate as catalyst. Three grades of PMMA–CCLs obtained by free radical copolymerization were used for synthesizing the PMMA-g–PA6 copolymers with different PMMA content. The resulting graft copolymer was characterized by Fourier-transform infrared spectroscopy and selective extraction. Scanning electron microscopy is used to clarify the phase morphology of obtained polymer by fracture surface. The thermal property, crystallinity and dimensional stability of graft copolymer were studied using differential scanning calorimetry, X-ray diffraction and water absorption measurement. The results show the T_g of graft copolymer is higher than that of neat PA6, but the onset and peak points of graft copolymer melting point are shifted to lower temperature. The percentage crystallinity and water absorption of PMMA-g–PA6 copolymer decrease with increasing PMMA content, but the crystal structure of PA6 is scarcely affected by the presence of PMMA. Graft copolymers have improved dimensional stabilities relative to neat PA6. Upon the incorporation of 19.9 wt% PMMA into PA6, the water absorption of PMMA-g–PA6 copolymer has been reduced from 4.8 for neat PA6 to 2.1%.     

Synthesis and characterization of a novel coil–rod–coil triblock copolymers comprised of regioregular poly(3-hexylthiophene) and poly(methyl methacrylate) segments

The synthesis of a new coil–rod–coil ABA triblock copolymers comprised of regioregular poly(3-hexylthiopene) (P3HT) and poly(methyl methacrylate) (PMMA) segments has been demonstrated by the combination of quasi-living Grignard metathesis (GRIM) polymerization and living anionic polymerization based on 1,1-diphenylethylene (DPE) chemistry. The method involves simple reaction steps, an in situ introduction of DPE moieties at the α,ω-ends of P3HT and the lithiation with sec-butyl lithium (sec-BuLi) to generate a macroinitiator bearing 1,1-diphenylalkyl anions, followed by cross-over to MMA. The selective α,ω-ends di-functionalization is a key step to achieve the ABA structure. The structural homogeneity of the precursor and block copolymer has been confirmed by gel permeation chromatography (GPC), GPC-right angle laser light scattering (RALLS), and nuclear magnetic resonance (NMR). The block copolymer has been fully characterized by differential scanning calorimetry (DSC), thermogravimetry analysis (TGA), Ultra-violet–visible (UV–vis) and photo luminescent (PL) spectroscopies, and atom force microscopy (AFM).     

Blends of ethylene–octene copolymers with different chain architectures – Morphology,thermal and mechanical behavior

Blends of two elastomeric ethylene–octene copolymers with similar octene contents having a random (ORC) and a blocky architecture (OBC) are prepared by melt mixing. The thermal and mechanical properties of ORC, OBC and their blends are investigated by DSC, dynamic mechanical analysis and tensile tests. The morphology of the semi-crystalline samples is studied by AFM and WAXS. Two types of crystals have been observed: (i) Orthorhombic crystals forming lamellae with an estimated thickness of about 13 nm composed mainly of long polyethylene-like sequences of OBC that melt a temperature of about 120 °C and (ii) fringed micellar crystals with a thickness of 2–4 nm formed basically by short polyethylene-like sequences of ORC that have melting temperatures between 30 and 80 °C. The amorphous phase contains a relatively homogeneous mixture of segments of both components indicated by the relatively uniform shape of the loss modulus peaks from dymamic-mechanical measurements for all investigated copolymers and blends. ORC crystallization is hindered in blends as indicated by lower melting enthalpies. This might be related to the high octene content of the amorphous phase at the relevant crystallization temperature as well as geometrical constraints since ORC crystallization occurs in an already semi-crystalline polymer. The results of tensile tests show that the mechanical behavior can be tailored via blend composition and morphology of the semi-crystalline material. The findings clearly indicate that blending is a powerful strategy to optimize the properties of polyolefin-based copolymers.     

Analysis and modeling of modified styrene–acrylonitrile/carboxylated acrylonitrile butadiene rubber nanocomposites filled with graphene and graphene oxide: Interfacial interaction and nonlinear elastoplastic behavior

Nonlinear elastoplastic behavior of the nanocomposites based on the styrene–acrylonitrile/carboxylated acrylonitrile butadiene rubber (SAN/XNBR) blend was investigated using experimental and theoretical analysis. Graphene, graphene oxide nanoparticles, and glycidyl methacrylate-grafted-XNBR (XNBR-g-GMA) as a compatibilizer were incorporated in the SAN/XNBR blends. In this regard, the focus of this study is on modeling of the stress–strain behavior of these nanocomposites, considering the effect of the interfacial interactions made by compatibilizer. For this purpose, field emission scanning electron microscopy (FESEM) and transmission electron microscope (TEM) techniques were used to investigate the relationship between microstructure and mechanical properties of nanocomposites. In addition, FESEM and TEM images showed that the presence of a compatibilizer could influence the dispersion and localization of the nanoparticles. According to the tensile test results, the presence of the compatibilizer increased the mechanical properties of the nanocomposites, specifically elongation at break. Considering the nanocomposite containing compatibilizer and graphene oxide, the elongation at break increased about 570% compared with the nanocomposite without compatibilizer. Better dispersion of graphene oxide and the creation of chemical interaction among components in the presence of the XNBR-g-GMA compatibilizer could be the reasons for these improvements, as confirmed by TEM. The usage of the Bergstrom–Boyce model for analyzing the nonlinear elastoplastic behavior of the nanocomposites illustrated proper conformity with the experimental data in the elastic region. However, there are some deviations in the viscoplastic region, particularly close to the breaking elongation region.     

Copolymerization behavior of 3-isopropenyl-α,α-dimethylbenzylamine and a preliminary evaluation of the copolymers in thermoset coatings

The title monomer was synthesized from 3-isopropenyl-α,α-dimethylbenzyl isocyanate in a significantly better yield than was previously reported. 3-Isopropenyl-α,α-dimethylbenzylamine proved incapable of homopolymerization using free-radical initiation but readily copolymerized with a variety of commonly available monomers under free-radical conditions. Films of some of the copolymers were prepared and crosslinked using a variety of multifunctional epoxy compounds. The films had good solvent resistance, high hardness, and good gloss. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1030–1039;2001