Synthesis,characterization, and thermal properties of alkyl‐functional naphthoxazines

A series of alkyl‐functional naphthoxazine resins having various alkyl chain lengths from C1 to C18 are synthesized with a high yield and high purity by the reactions of 1,5‐dihydroxynaphthalene, formaldehyde, and aliphatic amines. The proposed chemical structures of the naphthoxazines are confirmed by high‐resolution mass spectrometry, ¹H nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and pyrolysis mass spectrometry studies. The alkyl‐functional naphthoxazines have shown low polymerization temperature characteristics where polymerization of these monomers is achieved in the range of 150–170°C yielding cross‐linked polynaphthoxazines. The low‐temperature polymerization characteristics and the associated thermal degradation behaviors are studied. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and properties of PMMA‐ZrO2 organic–inorganic hybrid films

In this work we report the synthesis process and properties of PMMA‐ZrO₂ organic–inorganic hybrid films. The hybrid films were deposited by a modified sol‐gel process using zirconium propoxide (ZP) as the inorganic (zirconia) source, methyl methacrylate (MMA) as the organic source, and 3‐trimetoxy‐silyl‐propyl‐methacrylate (TMSPM) as the coupling agent between organic and inorganic phases. The films were deposited by dip coating on glass slide substrates from a hybrid precursor solution containing the three precursors with molar ratio 1 : 0.25 : 0.25 for ZP, TMSPM, and MMA, respectively. After deposition, the hybrid thin films were heat‐treated at 100°C for 24 h. The macroscopic characteristics of the hybrid films such as high homogeneity and high optical transparence evidenced the formation of a cross‐linked, interpenetrated organic–inorganic network. The deposited PMMA‐ZrO₂ hybrid films were homogeneous, highly transparent and very well adhered to substrates. Fourier Transform Infra‐Red measurements of the hybrid films display absorption bands of chemical groups associated with both PMMA and ZrO₂ phases. The amounts of organic and inorganic phases in the hybrid films were determined from thermogravimetric measurements. The surface morphology and homogeneity of the hybrid films at microscopic level were analyzed by scanning electron microscopy and atomic force microscopy images. From the analysis of optical transmission and reflection spectra, the optical constants (refraction index and extinction coefficient) of the hybrid films were determined, employing a physical model to simulate the hybrid optical layers. The refraction index of the hybrid films at 532 nm was 1.56. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42738.     

Flammability and thermal properties of high density polyethylene/paraffin hybrid as a form‐stable phase change material

In this study, form‐stable phase change material (PCM)–high density polyethylene (HDPE)/paraffin hybrid with different flame‐retardant systems are prepared by using twin‐screw extruder technique. This kind of form‐stable PCM is made up of paraffin (a dispersed phase change material) and a HDPE (a supporting material). Their structures and flammability properties are characterized by scanning electronic microscope (SEM) and cone calorimetry. Thermal stability is shown by thermogravimetry analysis (TGA) and its latent heat is given by differential scanning calorimeter (DSC) method. SEM results show that the HDPE forms a three‐dimensional net structure and the paraffin is dispersed in it. The peak of heat release rate (HRR) of the flame‐retardant form‐stable PCM decreases markedly. In TGA curves, although the onset of weight loss of flame‐retardant form‐stable PCMs occur at a lower temperature than that of form‐stable PCM, flame‐retardant form‐stable PCMs produce a large amount of char residue at 700°C. DSC results show that the addition of flame retardant has little effect on the phase change latent heat of PCM. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1320–1327, 2006     

Morphology,thermal and mechanical properties of the polyhedral oligomeric silsesquioxane side‐chain epoxy hybrid material

The side‐chain polyhedral oligomeric silsesquioxane (POSS)‐type epoxy (IPEP) hybrid material was synthesized, and the particle sizes of the POSS segment were less than 5 nm and which particles dispersed uniformly. The 3D AFM microphotograph of the IPEP/DGEBA (diglycidyl ether of bisphenol A) hybrid material exhibited the unique “island” shape, and their XRD pattern displayed amorphous halo structure. The POSS segments of the IPEP could improve the thermal degradation activation energies. Additionally, introduction of the IPEP into the DGEBA could improve the char yield and provide the antioxidation property in the air atmosphere. The char yields of the IPEP/DGEBA hybrid materials could improve from 14.48 to 19.21% and from 0.18 to 1.17% in the nitrogen and air atmospheres, respectively. The IPEP segments could also improve the hardness when the IPEP contents of the IPEP/DGEBA hybrid materials were less than 50 wt %. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation and characterization of PMMA–Clay hybrid composite by emulsion polymerization

Nanocomposites are prepared by a simple technique of emulsion polymerization using MMA monomer and Na⁺-montmorillonite. The products are purified by hot toluene extraction and characterized by FT-IR, X-ray diffraction, TGA, DSC, and tensile testing. The structural investigation confirms that the products are intercalated with PMMA chain molecules oriented parallel to the direction of lamellar layers whose separation is consequently more enlarged than in the polymer-free clay. DSC traces also corroborate the confinement of the polymer in the inorganic layer by exhibiting no observable transition in the thermogram. Both the thermal stability and tensile properties of the products appear to be substantially enhanced. The ion-dipole bonding is believed to be the driving force for the introduction and fixation of the organic polymer to the interfaces of montmorillonite. © 1996 John Wiley & Sons, Inc.     

Preparation and characterization of low density polyethylene‐agar biocomposites: Torque‐rheological,mechanical, thermal and morphological properties

Low density polyethylene (LDPE) and agar were blended by using the former as an internal mixer and varying the amount of agar. Resulting blends were hot pressed and characterized with regard to their torque‐rheological, mechanical, dynamic‐mechanical, thermal, and morphological properties. The torque rheological properties were determined using classical power law model. Tensile properties of LDPE‐agar biocomposites showed that agar improves the tensile modulus (stiffness), but compromise the tensile strength and elongation at break. Viscoelastic behavior of the matrix is clearly influenced by the presence of agar biofiller as shown by the dynamic mechanical analysis (DMA). Thermal behavior of the biocomposites was also investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphological observations by scanning electron microscopy (SEM) show the ductile to brittle fracture of LDPE‐agar biocomposites subjected to tensile test. This work is an initial reference to identify potential applications of biocomposites based‐on agar as a biofiller. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Synthesis,characterization and properties of clay‐polyacrylate hybrid materials

A new type of hybrid material of clay with poly (butyl acrylate) (PBA) has been prepared successfully using intercalation‐polymerization process. The structure of the composite was investigated by X‐ray diffraction (XRD), Fourier transform infrared (FTIR), Transmission electron microscope (TEM), and Thermogravimetric analysis (TGA). The results show that the hybrid material prepared has a decomposition central temperature of 485.6°C, 83°C higher than that of pure PBA (402.0°C). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 796–801, 2000     

Photocatalytic properties of PMMA‐TiO2 class I and class II hybrid nanofibers obtained by electrospinning

The preparation, characterization, and photocatalytic activity evaluation of three hybrid fibrous materials composed mainly by poly(methyl methacrylate) (PMMA), methyl methacrylate (MMA): 3‐(trimethoxysilyl) propyl methacrylate (TMSPM): titanium butoxide (TBT), TiO₂ nanoparticles (NPTiO₂), and TiO₂ nanowires (NWTiO₂) is studied. Two types of fibe?s structures were prepared, single and core‐shell structures. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed both structures, single and core‐shell, as well as the inorganic phase were dispersed in the hybrid fibers. Infrared spectroscopic analysis (FT‐IR) and thermal analysis showed the organic and inorganic components, as well as the weight percentage of the inorganic phase present in hybrid fibers. The photocatalytic activity of the hybrid fibers class I and II showed that the best photodegradative efficiency for methylene blue in aqueous solution (2.9 × 10^?5 M) was 95%, provided by PMMA—10 wt % NPTiO₂. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44334.     

Chemical and thermal characterization of high‐ and low‐density irradiated polyethylenes

A comparative study of the dynamic mechanical relaxation spectra of high‐ and low‐density polyethylenes irradiated with γ‐radiation from a Co⁶⁰ source was performed. The irradiation doses ranged from 0 to 100 Mrad. All the samples were previously characterized by determination of the molecular weight distribution, the number of functional groups, and the crystalline fraction. All the relaxation zones between ?145°C and the melt were studied in the frequency range from 0.3 to 30 Hz. The changes observed in the mechanical relaxation spectra were related to modifications in the chemical structure and morphological parameters attributed to the exposure of the samples to the γ‐radiation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1953–1958, 2002     

Synthesis,thermal properties,and flame retardance of phosphorus‐containing epoxy‐silica hybrid resins

A novel epoxy resin modifier, phosphorus‐containing epoxide siloxane (DPS) with cyclic phosphorus groups in the Si O network, was prepared from the reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) with polyhedral‐oligomeric siloxanes, which was synthesized by the sol–gel reaction of 3‐glycidoxypropyltrimethoxysilane. DPS was confirmed by Fourier transform infrared and ²⁹Si NMR measurement, and then was employed to modify epoxy resin at various ratios, with 4,4‐diaminodiphenyl‐methane as a curing agent. In order to make a comparison, DOPO‐containing epoxy resins were also cured under the same conditions. The resulting organic–inorganic hybrid epoxy resins modified with DPS exhibited a high glass transition temperature (T_g), a good thermal stability, and a high limited oxygen index. In addition, the tensile strength of cured products was also rather desirable. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

DGEBA‐grafted polyaniline: Synthesis,characterization and thermal properties

The utilization of conducting emeraldine salt (PANI‐ES) and intrinsic leucoemeraldine polyaniline (PANI‐LEB) in the synthesis of DGEBA‐grafted PANI via anionic copolymerization is described. The structures of copolymers obtained were characterized by FTIR, ¹³C and ¹H NMR. The extent of grafting was verified by THF Soxhlet (solvent extraction). The thermal properties of these new copolymers were described and their conductivities were reported. Results obtained indicated that the graft copolymer exhibited higher electrical and thermal conductivities than that of the blend counterpart. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

QSPR studies of polyvinyls by density functional theory

Density functional theory (DFT) calculations are carried out for polyvinyls repeating units at the B3LYP/6-31G(d) level, and the calculated results of E_T, E_int, C_v, S, Q_ii, μ, α and q⁻ are used to predict V (298 K), P_s, F_d, R_LL, χ, H_vsum, U_R and U_H. Multiple linear stepwise regression analysis is used to generate eight more physically meaningful quantitative structure-property relationship (QSPR) models having correlation coefficient R of 0.996 for V (298 K), 0.998 for P_s, 0.997 for F_d, 0.997 for R_LL, 0.997 for χ, 0.992 for H_vsum, 0.992 for U_R and 0.991 for U_H, and the conclusions are in consistence with theoretical analysis. Investigated results indicate QSPR models given here are easy to apply and have good predictive capability.     

Synthesis of PMMA‐PTHF‐PMMA and PMMA‐PTHF‐PST linear and star block copolymers

Combination of cationic, redox free radical, and thermal free radical polymerizations was performed to obtain linear and star polytetramethylene oxide (poly‐THF)‐polymethyl methacrylate (PMMA)/polystyrene (PSt) multiblock copolymers. Cationic polymerization of THF was initiated by the mixture of AgSbF₆ and bis(4,4′ bromo‐methyl benzoyl) peroxide (BBP) or bis (3,5,3′,5′ dibromomethyl benzoyl) peroxide (BDBP) at 20°C to obtain linear and star poly‐THF initiators with M_w varying from 7,500 to 59,000 Da. Poly‐THF samples with hydroxyl ends were used in the methyl methacrylate (MMA) polymerization in the presence of Ce(IV) salt at 40°C to obtain poly(THF‐b‐MMA) block copolymers containing the peroxide group in the middle. Poly(MMA‐b‐THF) linear and star block copolymers having the peroxide group in the chain were used in the polymerization of methyl methacrylate (MMA) and styrene (St) at 80°C to obtain PMMA‐b‐PTHF‐b‐PMMA and PMMA‐b‐PTHF‐b‐PSt linear and star multiblock copolymers. Polymers obtained were characterizated by GPC, FT‐IR, DSC, TGA, ¹H‐NMR, and ¹³C‐NMR techniques and the fractional precipitation method. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 219–226, 2004     

Synthesis,characterization, and thermal properties of poly(methylvinylsilylene‐co‐styrene)

The copolymerization of methylvinyldichlorosilane (MVDCS) and styrene was carried out with various monomer feed ratios under dechlorination conditions with sodium in toluene at 110°C. The copolymers were obtained in 84–95% yields. The copolymerization of MVDCS and styrene with monomer feed ratios of 1 : 0.25 and 1 : 0.5 mainly gave insoluble polymers. The copolymers synthesized with monomer feed ratios of 1 : 1, 1 : 3, and 1 : 7 contained soluble fractions of 3, 26, and 47%, respectively. The copolymers were characterized with infrared, ¹H‐NMR, gel permeation chromatography, thermogravimetric analysis, pyrolysis/gas chromatography (PGC), X‐ray diffraction, and elemental analysis (silicon content). ¹H‐NMR and PGC studies suggested that the soluble fractions were mainly polystyrene. PGC studies indicated that the copolymers obtained with monomer feed ratios of 1 : 0.25 and 1 : 0.5 did not have any significant amount of polystyryl blocks, whereas the copolymers obtained with higher styrene feed ratios contained appreciable amounts of polystyryl blocks. The composition of the insoluble fractions of the copolymers was obtained from PGC data and was in good agreement with the composition calculated from the silicon content of the copolymers.© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91:3774–3784, 2004     

PMMA‐grafted‐silica/PVC nanocomposites: Mechanical performance and barrier properties

Poly(vinyl chloride) (PVC)/SiO₂ nanocomposites were prepared via melt mixture using a twin‐screw mixing method. To improve the dispersion degree of the nanoparticles and endow the compatibility between polymeric matrix and nanosilica, SiO₂ surface was grafted with polymethyl methacrylate (PMMA). The interfacial adhesion was enhanced with filling the resulting PMMA‐grafted‐SiO₂ hybrid nanoparticles characterized by scanning electron microscopy. Both storage modulus and glass transition temperature of prepared nanocomposites measured by dynamic mechanical thermal analysis were increased compared with untreated nanosilica‐treated PVC composite. A much more efficient transfer of stresses was permitted from the polymer matrix to the hybrid silica nanoparticles. The filling of the hybrid nanoparticles caused the improved mechanical properties (tensile strength, notched impact strength, and rigidity) when the filler content was not more than 3 wt %. Permeability rates of O₂ and H₂O through films of PMMA‐grafted‐SiO₂/PVC were also measured. Lower rates were observed when compared with that of neat PVC. This was attributed to the more tortuous path which must be covered by the gas molecules, since SiO₂ nanoparticles are considered impenetrable by gas molecules. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,thermal properties,and flame retardance of the epoxy‐silsesquioxane hybrid resins

Epoxy/silsesquioxane‐OH (EP‐SDOH, ED) hybrid resins were prepared from cyclohexyl‐disilanol silsesquioxane (SDOH) and diglycidyl ether of bisphenol A via the reaction between silanol and the oxirane group, with the cobalt naphthanate as a catalyst. It was found that incorporation of SDOH allows the reaction between oxirane ring and Si? OH, and the silsesquioxane cage structure can be the main chain or as the side chain of the hybrid resin. The EP‐SDOH hybrid resins with various SDOH contents were cured by 4,4′‐diaminodiphenylsulphone, and the curing reaction was investigated by differential scanning calorimetry. The curing characteristics of EP‐SDOH hybrids had been observed to be influenced by the content of SDOH in the hybrid. The differential scanning calorimetry thermograms indicated that the EP‐SDOH hybrid exhibited a higher initial temperature, peak temperature, as well as final temperature than those of the pure epoxy resin when cured by the same curing agent 4,4′‐diaminodiphenylsulphone. The curing kinetic parameters were calculated by using the Ozawa method and the results indicated that EP‐SDOH hybrids possess the same curing mechanism as the pure epoxy resin. The properties of the cured EP‐SDOH hybrid resins such as the glass transition temperature (T_g), dynamic mechanical analysis, thermal stability, as well as the flame retardance were also investigated, and the results showed that introducing silsesquioxane‐OH unit into epoxy resin successfully modified the local structure, made the chain stiffness, restrict the chain mobility, and eventually improved thermal stability and flame retardance of epoxy resin. POLYM. ENG. SCI., 47:225–234, 2007. © 2007 Society of Plastics Engineers.     

Ortho‐ and meta‐substituted polystyrene polyperoxides: synthesis,characterization and thermal decomposition studies

The alternating copolymers of vinyl monomers with molecular oxygen (polyperoxides) show numerous novel physicochemical properties such as high exothermic degradation. In the work presented, polyperoxides were prepared by oxidative polymerization of ortho‐ and meta‐substituted styrene monomers in toluene in the presence of 2,2′‐azobisisobutyronitrile free radical initiator at 50 °C and 0.69 MPa oxygen pressure. The polymeric peroxides of styrene monomers with substituents in the ortho‐ and meta‐positions thus obtained were characterized using NMR and Fourier transform infrared spectroscopies, elemental analysis and electron impact mass spectrometry to confirm the alternating copolymer structure with peroxy bonds in the backbone. Differential scanning calorimetry and thermogravimetric analysis were used to study the exothermic thermal degradation of these polyperoxides. For these polyperoxides, the measured heats of degradation ( ) were found to lie between ?169 and ?180 kJ mol^?1, which are comparable with the values of other vinyl polyperoxides. The exothermic degradation mechanism is supported by thermochemical calculations. © 2013 Society of Chemical Industry     

Synthesis,structures, and density functional theory computational study of thiophene‐containing and fluorodecorated imine‐linked polymers

A new series of extended–conjugated and thermally stable thiophene‐containing imine‐linked polymers were synthesized via a Schiff‐base condensation reaction between aryl aldehydes and 2,6‐diaminopyridine building blocks. The backbones of the polymers were functionalized with phenyl, fluorosubstituted phenyl, thienyl, and pyridyl aromatic rings. The successful synthesis was confirmed with spectrochemical characterization techniques, including IR, ¹H‐NMR, ¹³C‐NMR, and elemental analyses. The electronic properties of the polymers were investigated with ultraviolet–visible (UV–vis) absorption spectroscopy; the properties were collected experimentally and calculated with density functional theory (DFT) in the gas phase. The maximum absorption calculated from DFT was higher than the experimental values by about 60 nm; this was attributed to the absence of the solvent effect in the DFT case. The frontier molecular orbital ((HOMO) highest occupied molecular orbital and (LUMO) lowest unoccupied molecular orbital), optical band gap (E_g), and total energy (E_T) values of the optimized structures were calculated. Apparently, there was a significant relation between the number of thiophene rings and the resulting E_g and E_T values. As the number of thiophene rings in the polymer chain increased, E_g and E_T decreased, and the thermal stability of the polymers increased. E_g and the absorption band edges were determined experimentally from the UV–vis and transmittance spectra, respectively. Poly(terthienyl–azomethine–pyridine–azomethine), with the highest thiophene content, had the lowest experimental and calculated E_g values (2.10 and 2.63 eV, respectively). In contrast, upon fluorination, poly[(2,5‐dithienyl–1,4‐difluorobenzene)–azomethine–pyridine–azomethine] exhibited the highest E_g (2.81 eV) and absorption band edges (2.94 eV), whereas the thermal stability decreased to 250 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44331.     

Structural and thermal characterization of macro-branched functional terpolymer containing 8-hydroxyquinoline moieties with enhancing biocidal properties

Novel polyfunctional acetyl and hydroxyl bearing functional terpolymer (HQFCA) derived from 8-hydroxyquinoline (HQ), 4-chloroacetophenone (CA) and formaldehyde (F) has been synthesized by complex condensation polymerization in the presence of an acid catalyst. The structure and morphology of terpolymer were elucidated by FTIR-ATR, one-dimensional NMR (¹H NMR, ¹³C NMR and DEPT-135 experiment), two-dimensional NMR (HSQC and TOCSY), pyrolysis GC–MS, gel permeation chromatography (GPC), nitrogen absorption, and optical microscopy (OM). Principal pyrolysis products generated from HQFCA units were 8-hydroxy-5,6-dimethylquinoline, 8-hydroxy-2-methylquinoline and 4-chloroacetophenone. This reactive terpolymer can be used as synthons for exchange membrane preparation and biomedical coating applications.