Synthesis and characterization of polyurethaneurea–vinyl polymer (PUU–VP) uniform hybrid microspheres by SPG emulsification technique and subsequent suspension polymerization

Uniform polyurethaneurea–vinyl polymer (PUU–VP) hybrid microspheres of about 20 μm were prepared by a Shirasu porous glass (SPG) membrane emulsification technique and a subsequent radical suspension polymerization process, that is, a mixture of a 40 wt % urethane prepolymer (UP) solution of xylene and a vinyl monomer (VP) containing an initiator was permeated through the uniform pores of the SPG membrane into a continuous phase containing a stabilizer to form uniform droplets. Then, the droplets were allowed to stand for chain extension at room temperature with di‐ or triamines for 2 h in the absence or presence of ethyl acetate (EA), followed by suspension polymerization at 70°C for 24 h. The effect of the type and the amount of the monomer composition, crosslinker, and chain extender on the monomer conversion, particle morphology, and stability of the dispersion was investigated. A strong relationship was found between the compatibility of PUU with VP and the stability of the dispersion. The monomer conversion increased and the stability of the dispersion was improved as the amount of the crosslinker was increased. Solid and spherical PUU–VA hybrid particles with a smooth surface and a higher destructive strength were obtained when a trifunctional crosslinker and a chain extender were used together. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 163–178, 2003     

Preparation and characterization of pH‐ and temperature‐responsive semi–interpenetrating polymer network hydrogels based on linear sodium alginate and crosslinked poly(N‐isopropylacrylamide)

In this study, pH‐ and temperature‐responsive hydrogels based on linear sodium alginate (SA) and crosslinked poly(N‐isopropylacrylamide) (PNIPAAm) were prepared by semi‐interpenetrating network (semi‐IPN) technique. The dually responsive hydrogels were characterized by FTIR, DSC, and SEM, and their temperature‐ and pH‐responsive behaviors were investigated by measuring equilibrium swelling ratios and pulsatile swelling experiments. The results showed that these hydrogels underwent volume phase transition at around 33°C irrespective of the pH value of the medium, but their pH sensitivity was evident only below their volume phase transition temperature. Under basic conditions, the swelling ratios of SA/PNIPAAm semi‐IPN hydrogels were greater than that of pure PNIPAAm hydrogel and increased with increasing SA content incorporated into the hydrogels, but the case was inverse under acidic conditions. The pulsatile swelling experiments indicated that the higher the SA content in SA/PNIPAAm semi‐IPN hydrogels, the faster the response rate to both pH and temperature change. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1931–1940, 2005     

Novel organic–inorganic hybrid coatings prepared by the sol–gel process: corrosion and mechanical properties

(Hyperbranched polyurethane‐urea)/[(3‐aminopropyl)triethoxysilane]‐ZnO (HBPUU‐APTES‐ZnO) hybrid coatings were synthesized using an inexpensive mixing technique by varying the APTES‐modified ZnO concentration. The mechanical and surface properties of the hybrid coating films were studied and compared with unmodified and modified ZnO. The corrosion, solvent and abrasion resistance show significant enhancement in HBPUU‐APTES‐ZnO hybrids and their properties are increased with increasing APTES‐ZnO concentration. This hybrid coating has opened up an opportunity for automotive topcoat application. Copyright © 2012 Society of Chemical Industry     

Preparation and characterization of hybrid organic–inorganic epoxide‐based films and coatings prepared by the sol–gel process

Hybrid organic–inorganic coatings and free‐standing films were prepared and characterized. The hybrids were prepared from [3‐(glycidyloxy)propyl]trimethoxysilane, diethoxy[3‐(glycidyloxy)propyl]methylsilane, poly(oxypropylene)s of different molecular weights end‐capped with primary amino groups (Jeffamines D230, D400, and T403), and colloidal silica particles with hydrochloric acid as a catalyst for the sol–gel process and water/propan‐2‐ol mixtures as solvents. The structure evolution during the network formation was followed by NMR spectroscopy and small‐angle X‐ray scattering; the surface morphology was tested by atomic force microscopy. The influence of the reaction conditions (the organosilicon precursor, oligomeric amine, ratio of functional groups, and method of preparation) on the network buildup and product properties was studied and examined. The mechanical testing, based on stress–strain experiments, in combination with dynamic mechanical thermal analysis served as an effective instrument for the optimization of the reaction conditions for the preparation of products with desired properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 937–950, 2004     

Preparation and properties of organic–inorganic hybrid composites based on polystyrene and an incompletely condensed polyvinylsilsesquioxane oligomer

An incompletely condensed polyvinylsilsesquioxane (PVSQ) oligomer containing abundant silanol groups was synthesized and characterized by FTIR, ¹H‐NMR, ²⁹Si‐NMR, and MALDI‐TOF‐MS. Polystyrene/polyvinylsilsesquioxane (PS/PVSQ) hybrid composites were prepared by an in situ bulk polymerization. The hybrid composites showed higher T_g, T_d, and char yield than PS homopolymer and without mechanical loss. The improvements in the properties of PS/PVSQ hybrid composites can be ascribed to the crosslinking function of PVSQ by silanol condensation in later processing. The hybrids showed different morphology from discrete microstructure to continuous network depending on the concentration of PVSQ. Because of the surface enrichment, a PVSQ protection layer was formed, which made the hybrid surface more hydrophobic. The structure and the reaction mechanism of PS/PVSQ hybrid composites were also investigated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparison of the pervaporation separation of a water–acetonitrile mixture with zeolite‐filled sodium alginate and poly(vinyl alcohol)–polyaniline semi‐interpenetrating polymer network membranes

The pervaporation (PV) separation performance of ZSM‐5‐ and Na‐Y‐type zeolite‐filled sodium alginate (NaAlg) membranes were compared with those of pure NaAlg and semi‐interpenetrating polymer network (semi‐IPN) membranes of poly(vinyl alcohol) (PVA) with polyaniline (PANI) for the dehydration of acetonitrile. The PV separation characteristics of the zeolite‐filled membranes showed a dependence on the nature of the zeolites. The variation of the acidity function of the ZSM‐5 zeolite had an influence on the flux and selectivity of the membranes when compared to unfilled membranes. The crosslinked membranes were characterized by differential scanning calorimetry, X‐ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Increasing the PANI content of the semi‐IPN network increased the separation selectivity. Among the NaAlg membranes, the plain NaAlg membrane showed the highest selectivity of 414 at 30 mass % water in the feed mixture, whereas the Na‐Y‐ and ZSM‐5 (40)‐filled NaAlg membranes exhibited much lower values of selectivity, that is, 7.3 and 4.3, respectively for 30 mass % water in the feed. When the flux and selectivity data of ZSM‐5 (250)‐filled NaAlg membranes were compared with that of Na‐Y‐ or ZSM‐5 (40)‐filled NaAlg membranes, a noticeable increase in the selectivity for the ZSM‐5 (250)‐filled NaAlg membrane was observed, but a somewhat comparable flux was observed compared to the plain NaAlg membrane. For the first time, PANI was polymerized with PVA to yield a semi‐IPN. The total flux and water flux increased systematically, whereas the selectivity decreased greatly from 251.87 to 5.95 with increasing amounts of water in the feed. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1968–1978, 2005     

Thermal conductivity and thermal properties of POSS/polytriazole organic–inorganic hybrid material

To decrease the thermal conductivity of polytriazole‐based fiber reinforced composites, an organic–inorganic POSS/polytriazole hybrid resin was obtained. The influences of various proportions of POSS on thermal conductivity and the thermal properties of hybrid materials were emphatically investigated. The results show that POSS incorporation resulted in not only decreased thermal conductivity but also increased T_g and thermal decomposition temperature. The enhancement was ascribed to the nanoscale effect of POSS structure and the fact that the POSS framework has a high heat resistance property. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41967.     

Preparation and characterization of organic–inorganic hybrid composites based on multiepoxy silsesquioxane and cyanate resin

A multiepoxy cubic silsesquioxane was prepared by the hydrolysis and polycondensation of trifunctional monomer (γ‐glycidoxypropyl)trimethoxysilane in a solvent mixture of methyl isobutyl ketone and anhydrous ethanol with a tetraethyl ammonium hydroxide aqueous solution acting as the catalyst, and it was successfully introduced into a cyanate resin and formed highly crosslinked organic–inorganic hybrid composites on a molecular level via a mutual cure reaction. The properties of the multiepoxy cubic silsesquioxane/bisphenol A dicyanate ester resin composites were investigated, and the results showed that introducing the cubic silsesquioxane unit into the cyanate resin successfully modified the local structure of the molecule, made the chain more rigid, restricted the chain mobility, and eventually improved the thermal stability and flame retardancy of the resin. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3652–3658, 2006     

Barrier properties of organic–inorganic hybrid coatings based on polyvinyl alcohol with improved water resistance

A comprehensive study of the gas barrier properties of hybrid organic–inorganic coatings formed by polyvinyl alcohol (PVOH) and Si‐SiO₂, obtained via sol–gel technique, was carried out. It has been shown that the oxygen, nitrogen and carbon dioxide transfer rates of barrier polymers such as poly(ethylene terephthalate) and oriented polypropylene can be further reduced, by up to two orders of magnitude, with a thin coating (1–2 μm) of PVOH/Si‐SiO₂. More notably, it has been observed that the material maintains this feature even after a prolonged contact with water, which is a strong solvent for PVOH. Direct moisture sorption measurements show that silica lowers the water uptake of PVOH and inhibits sorption‐induced swelling and plasticization of the polymer. Correlations between the gas transport properties of the hybrid coatings and factors such as the silica content, the type of polymeric substrate, the nature of penetrant and the temperature have been found, providing guidelines for the selection and design of multilayer materials for packaging applications. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Physical and electrochemical properties of low molecular weight poly(ethylene glycol)‐bridged polysilsesquioxane organic–inorganic composite electrolytes via sol–gel process

A new class of ionic conducting organic/inorganic hybrid composite electrolyte with high conductivity, better electrochemical stability and mechanical behavior was prepared through the sol–gel processing between ethylene‐bridged polysilsesquioxane and poly(ethylene glycol) (PEG). The composite electrolyte with 0.05 LiClO₄ per PEG repeat unit has the best conductivity up to 10^?4 S/cm at room temperature with the transference number up to 0.48 and an electrochemical stability window as high as 5.5 V versus Li/Li⁺. Moreover, the effect of the PEG chain length on the properties of the composite electrolyte has also been studied. The interactions between ions and polymer have also been investigated for the composite electrolyte in the presence of LiClO₄ by means of FTIR, DSC, and TGA. The results indicated the interaction of Li⁺ ions with the ether oxygen of the PEG, and the formation of transient crosslinking with LiClO₄, resulting in an increase of the T_g of the composite electrolyte. The VTF‐type behavior of the ionic conductivity implied that the diffusion of the charge carriers was assisted by the segmental motions of the polymer chains. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2752–2758, 2007     

Synthesis and swelling properties of pH‐ and temperature‐sensitive interpenetrating polymer networks composed of polyacrylamide and poly(γ‐glutamic acid)

Novel hydrogels of interpenetrating polymer networks (IPNs) composed of polyacrylamide and poly(γ‐glutamic acid) were synthesized. In these systems, both polymers were crosslinked independently; this reduced the potential loss of a polymer during the washing process, as often occurs in semi‐IPN systems. Interpolymer interactions were investigated with Fourier transform infrared spectroscopy and differential scanning calorimetry. These studies suggested possible interactions between both polymers by the formation of hydrogen bonds. The swelling behavior of these hydrogels was analyzed by immersion of the hydrogel samples in deionized water at 25 and 37°C and in buffer solutions with pHs of 3, 7, and 10. The kinetics of swelling showed increases in the values of the swelling ratio with increasing immersion time in the swelling medium, molar proportion of the biopolymer in the hydrogel, temperature, and pH of the swelling medium. All of the hydrogels swelled rapidly and reached equilibrium in an average time of 40 min. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Writing–erasing properties and characterizations of hybrid materials based on disperse red by sol–gel process

We investigated the synthesis and writing–erasing properties of three different hybrid materials (SGDR1, SGDR13 and SGDR19) based on disperse red by the sol–gel process. The sol–gel process was undergone using tetraethyl orthosilicate (TEOS) as a precursor. Optical properties of three hybrid materials are compared as structurally similar materials (SGDR1, SGDR13 and SGDR19). The diffraction efficiency, reversible photoinduced process and writing–erasing properties of hybrid materials were measured as a function of time. The diffraction efficiencies of SGDR1, SGDR13, and SGDR19 films were observed up to a level of 0.65%, 0.24%, and 0.99%, respectively. AFM view of the surface relief grating on the SGDR19 film showed a depth of 15 nm and a surface distance of 2.50 μm.     

Coimmobilization of malic enzyme and alanine dehydrogenase on organic–inorganic hybrid gel fibers and the production of L‐alanine from malic acid using the fibers with coenzyme regeneration

Malic enzyme (EC 1.1.1.39) and alanine dehydrogenase (EC 1.4.1.1) were entrap‐immobilized on hybrid gel fibers of cellulose acetate (CA) and zirconium (Zr) alkoxide by air‐gap wet spinning. The production of L ‐alanine from malic acid with coenzyme regeneration was examined with the enzymes immobilized on the fibers. The productivity of L ‐alanine of the immobilized enzymes decreased to approximately one‐fifth of that of free enzymes, but the CA–Zr‐fiber‐immobilized enzymes retained a high level of productivity after repeated use. Reduced form of nicotinamide adenine dinucleotide (NADH) recycling also occurred effectively for the enzymes immobilized on the fiber. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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.     

Mechanical,surface, and thermal properties of polyamideimide–polydimethylsiloxane nanocomposites fabricated by sol–gel process

Polyamideimide (PAI)–epoxysilane (coupling agent) composites were reacted with oligomeric polydimethylsiloxane (PDMS), a condensation product of difunctional silane, by using the sol–gel process, and were then dried into films. After this procedure, the surface, mechanical, and thermal properties were measured. The study showed that PDMS existed in the PAI matrix by the use of FTIR. With respect to mechanical properties, the maximum elongation and toughness were increased in the PAI with silane groups, although the maximum tensile strength was slightly decreased. In this experiment, PAI–30 wt % epoxysilane composite had the best mechanical properties. The intensive dispersion of the silane groups on the surface of PAI was confirmed through XPS measurement. As a function of the siloxane contents, the TGA curve shows less thermal stability in terms of their initial weight loss. However, in an oxygen atmosphere at about 700°C, the series of PAI–siloxane composites indicated a significant increase in char concentration. In the end, PAI with a relevant amount of silane groups was improved in both toughness and surface properties. This experiment showed that PDMS added to PAI had better properties than those of classical materials. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1774–1783, 2004     

Thermal and optical properties of PMMA–titania hybrid materials prepared by sol‐gel approach with HEMA as coupling agent

A series of sol‐gel derived organic–inorganic hybrid materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic titania (TiO₂) were successfully synthesized by using 2‐hydroxyethyl methacrylate (HEMA) as coupling agent. In this work, HEMA is first copolymerized with methyl methacrylate monomer at specific feeding ratios by using benzoyl peroxide (BPO) as initiator. Subsequently, the as‐prepared copolymer (i.e., sol‐gel precursor) is then cohydrolyzed with various contents of titanium butoxide to afford chemical bondings to the forming titania networks to give a series of hybrid materials. Transparent organic–inorganic hybrid materials with different contents of titania are always achieved. Effects of the material composition on the thermal stability, optical properties, and morphology of neat copolymer and a series of hybrid materials, in the form of both coating and free‐standing film, are also studied by differential scanning calorimetry, thermogravimetric analysis, UV–Vis transmission spectra, refractometer, and atomic force microscopy, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 400–405, 2004     

Synthesis and swelling properties of pH‐sensitive hydrogels based on chitosan and poly(methacrylic acid) semi‐interpenetrating polymer network

A novel semi‐interpenetrating polymer network (semi‐IPN) hydrogel composed of chitosan and poly(methacrylic acid) was synthesized using formaldehyde as a crosslinker. The amount of crosslinker was searched and optimized. The structure of the hydogel was investigated by Fourier transform infrared (FTIR) spectroscopy. The spectrum shows that a structure of polyelectrolyte complex exists in the hydrogel. The effects of pH, ionic strength, and inorganic salt on the swelling behaviors of the hydrogel were studied. The results indicate the hydrogel has excellent pH sensitivity in the range of pH 1.40 to 4.50, pH reversible response between pH 1.80 and 6.80, and ionic strength reversible response between ionic strength 0.2 and 2.0M. The results also show that the hydrogel has a bit higher swelling capacity in a mix solution of calcium chloride (CaCl₂) and hydrochloric acid (HCl) solution than in a mix solution of sodium chloride (NaCl) and HCl. These results were further confirmed through morphological change measured by scanning electron microscope (SEM). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1720–1726, 2005     

Synthesis and properties of the semi‐interpenetrating polymer network–like,thermosensitive poly(N‐isopropylacrylamide) hydrogel

A new strategy was used to prepare a semi‐interpenetrating polymer network (semi‐IPN)–like poly(N‐isopropylacrylamide) (PNIPAAm) polymeric hydrogel, consisting of either low (2300) or high (33,000) molecular weight linear PNIPAAm chains and the crosslinked PNIPAAm network. The properties of the resulting PNIPAAm hydrogels were characterized by DSC and SEM as well as their swelling ratios at various temperatures, the deswelling in hot water (48°C), and the oscillating shrinking–swelling properties within small temperature cycles. It was found that the deswelling rate of these semi‐IPN–like PNIPAAm hydrogels was improved if the molecular weight and/or composition of the linear PNIPAAm chains within the semi‐IPN–like PNIPAAm hydrogels were increased. This improved deswelling rate was attributed to the fast response nature of the linear PNIPAAm chains and the increased pore number in the matrix network, which provided numerous water channels for the water to diffuse out during the deswelling process at a temperature above the lower critical solution temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1935–1941, 2003     

Rubber-elasticity of hybrid organic–inorganic composites evaluated using dynamic mechanical spectroscopy and equilibrium swelling

Estimations of the average molar mass between crosslinks for sol-gel-derived poly(tetramethylene oxide) (PTMO)–polysilicate hybrid composites have been made using both dynamic tensile modulus and equilibrium swelling techniques. Modulus-based calculations have been performed using storage modulus values obtained from dynamic mechanical spectroscopy at frequencies ranging from 0.1 to 10 Hz. The analysis revealed that gels containing either 4 or 19% polysilicate (by volume) had an average molar mass between crosslinks significantly less than that predicted by a PTMO and SiO₂ rule of mixtures. Thus, the analysis indicates that there is extensive restriction of PTMO chain mobility in these gels. Aging of the 19% polysilicate-loaded gels in a basic ethylamine and water solution for 25 h, which has previously been shown to enhance phase separation without loss of optical transparency, results in increasing average chain length. To verify this approach, the values obtained using the dynamic mechanical spectroscopy-based technique were compared with those calculated using the Flory-Rehner equation. Somewhat surprisingly, the analyses by both techniques were in excellent agreement, thereby suggesting that, in the absence of chemical change, elementary rubber elasticity theory is a good tool for investigating the phase interactions in these seemingly nonideal hybrid composites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 947–957, 1998     

Synthesis and characterization of fluorinated organic–inorganic hybrid coatings on tinplate

Fluorinated organic–inorganic hybrid coatings with interpenetrating network for corrosion protection of tinplate were prepared by hydrolysis and condensation reaction of tetraethoxysilane and 3‐methacryloxypropyltrimethoxysilane, followed by radical polymerization of trimethylolpropane triacrylate dodecafluoroheptyl methacrylate. The highly crosslinked organic network was developed and attached to the inorganic moieties through covalent Si–C bonds. The hybrid coatings were characterized by scanning electron microscope, water contact angle, Fourier transformed infrared spectroscopy, and thermogravimetric analysis. Their anticorrosion performances were evaluated by potentiodynamic polarization, electrochemical impedance spectroscopy and salt spray test. The results indicated that the fluorinated hybrid coatings exhibited excellent anticorrosion ability by forming a hydrophobic physical barrier between tinplate substrate and its external environment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42428.