Synthesis of a poly(methyl methacrylate)/silica nano-composite by soaking of a microphase separated polymer film into a perhydropolysilazane solution

A novel synthetic method of poly(methyl methacrylate) (PMMA)/silica nano-composite with well-segregated PMMA and silica domains was proposed. To obtain the nano-composite, a poly(methyl methacrylate)-block-poly(2-hydroxyethyl methacrylate) (PMMA-block-PHEMA) film with PMMA and PHEMA domains was soaked into a pyridine/m-xylene/perhydropolysilazane (PHPS) mixture and calcinated at 90 °C under steam. PHPS was homogeneously introduced into the film and selectively converted to silica in PHEMA microdomains of the PMMA-block-PHEMA film. The morphology of the nano-composite was investigated by transmission election microscopy (TEM).     

Conversion of Solution‐Derived Perhydropolysilazane Thin Films into Silica in Basic Humid Atmosphere at Room Temperature

Spin‐on perhydropolysilazane (PHPS) thin films were converted into mechanically hard silica thin films by an exposure to the vapor from aqueous ammonia. Infrared absorption and X‐ray photoelectron spectroscopic analyses were conducted to clarify the details of the PHPS‐to‐silica conversion and the nature of the silica thin film products. The PHPS‐to‐silica conversion was found to proceed rapidly between 2 and 3 h of exposure via a reaction‐limited process, where the refractive index and the pencil hardness greatly decreased and increased, respectively. Finally, the O/Si mole ratio close to 2 was achieved, which has never been realized in literature for PHPS‐derived silica thin films. It was also found that the condensation of Si–OH groups proceeds in films immediately after PHPS hydrolysis, which is similar to the base‐catalyzed hydrolysis–condensation reaction of silicon alkoxides. Although the silica thin films obtained had refractive indices similar to that of silica glass, high pencil hardness over 9H on Si(100) substrates, and O/Si mole ratios close to 2, it was concluded that they are nonidentical to silica glass, containing trace amounts of Si–OH and Si–H groups.     

Hard coatings on polycarbonate plate by sol‐gel reactions of melamine derivative,PHEMA, and silicates

Hard coatings were deposited on a polycarbonate plate using a sol‐gel process with a melamine derivative, PHEMA, and silicates, and examined as potential substitutes for glass in cars. Poly(2‐hydroxyethyl methacrylate) was partially functionalized with (3‐isocyanatopropyl)triethoxysilane, and the synthesized polymer was used to form a coating solution with methylated poly(melamine‐co‐formaldehyde), tetraethoxysilane, and methyltriethoxysilane. The coatings on the polycarbonate plate were deposited using a sol‐gel process. Precoating with poly(methyl methacrylate) was carried out to improve the adhesive strength of the coating. The optimum conditions and formulation to obtain excellent physical properties of the coating were determined. Smooth coatings with the hardness of a 3H class pencil, excellent abrasion resistance, and transparency were formed. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Grafting polymer from poly(ethylene terephthalate) films by surface‐initiated ATRP

Surface‐initiated atom transfer radical polymerization (ATRP) from poly(ethylene terephthalate) (PET) film was studied. Poly(methyl methacrylate) (PMMA), poly (acrylamide) (PAAM), and their diblock copolymer (PMMA/PAAM) on the surface of PET film were successfully prepared by surface‐initiated ATRP. The structures and properties of the modified PET film were characterized by FT‐IR/ATR, X‐ray photoelectron spectroscopy (XPS), measurements of contact angles, and scanning electronic microscopy (SEM). The results indicate that the surface properties of PET film were greatly improved by grafted polymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polyester resin as a compatibilizing agent for some polymeric blends

Dielectric and viscosity techniques were used to determine the degree of the compatibility of poly(methyl methacrylate)/polycarbonate, poly(methyl methacrylate)/ polystyrene, and polycarbonate/polystyrene blends in different ratios (25/75, 50/50, and 75/25 w/w). The effect of the addition of 5, 10, and 20% concentrations of the prepared polyester resin [poly(butylene terephthalate adipate)] on the compatibility of these blends was studied. The dielectric properties were measured over a frequency range (from 100 Hz to 100 kHz) at various temperatures covering the glass‐transition temperatures of the polymers used (from 30 to 170°C). It was found from the dielectric and viscosity measurements that the addition of 10% polyester to poly(methyl methacrylate)/polycarbonate, 20% polyester to poly(methyl methacrylate)/polystyrene, and 5% polyester to polycarbonate/polystyrene blends enhanced the degree of compatibility of such blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of baking treatment and materials composition on the properties of bulky PMMA–silica hybrid sol–gel materials with low volume shrinkage

A series of bulky PMMA–silica hybrid sol–gel materials had been successfully prepared through the conventional HCl‐catalyzed sol–gel approach with 2‐hydroxyethyl methyl methacrylate (HEMA) as coupling agent under pumping pretreatment (i.e., exhaustive vacuum evacuation). In this work, the hydroxyl groups of HEMA monomers were first cohydrolyzed with various contents of tetraethyl orthosilicate (TEOS) to afford chemical bonding for the forming silica networks by removal of solvent and byproduct of sol–gel reactions through pumping pretreatment before gelation reactions. Subsequently, the resultant viscous solution was then copolymerized with methyl methacrylate (MMA) monomers at specific feeding ratios by using benzoyl peroxide (BPO) as free‐radical initiator. Eventually, transparent bulky organic–inorganic hybrid sol–gel materials loaded with different silica content were always achieved. The obtained bulky hybrid sol–gel materials were found to be transparent, crack‐free, and of relatively low volume shrinkages even in high silica content. The as‐prepared bulky hybrid sol–gel materials were then characterized through silicon element mapping studies of energy‐dispersive X‐ray (EDX) and transmission electron microscopy (TEM). Effect of heating process at 150°C for 5 h after polymerization and material composition on the thermal properties, mechanical strength, and optical clarity of a series of bulky PMMA–silica hybrid sol–gel materials was investigated and compared by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), hardness test, dynamic mechanical analysis (DMA), and UV–vis transmission spectroscopy, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1151–1159, 2006     

Synthesis,characterization, and in vitro release of ibuprofen from poly(MMA‐HEMA) copolymeric core–shell hydrogel microspheres for biomedical applications

This article describes the development of a new crosslinked poly(methyl methacrylate‐2‐hydroxyethyl methacrylate) copolymeric core–shell hydrogel microsphere incorporated with ibuprofen for potential applications in bone implants. Initially poly(methyl methacrylate) (PMMA) core microspheres were prepared by free‐radical initiation technique. On these core microspheres, 2‐hydroxyethyl methacrylate (HEMA) was polymerized by swelling PMMA microspheres with the HEMA monomer by using ascorbic acid and ammonium persulfate. Crosslinking monomers such as ethylene glycol dimethacrylate (EGDMA) has also been included along with HEMA for polymerization. By this technique, it was possible to obtain core–shell‐type microspheres. The core is a hard PMMA microsphere having a hydrophilic poly(HEMA) shell coat on it. These microspheres are highly hydrophilic as compared to PMMA microspheres. The size of the hydrogel microspheres almost doubled when swollen in benzyl alcohol. These microspheres were characterized by various techniques such as optical microscopy, scanning electron microscopy, Fourier‐transformed infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The particle size of both microspheres was analyzed by using Malvern Master Sizer/E particle size analyzer. The in vitro release of ibuprofen from both microspheres showed near zero‐order patterns. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3045–3054, 2002; DOI 10.1002/app.10310     

聚氨酯/聚甲基丙烯酸甲酯互穿网络的阻尼性能及相态

引言聚合物互穿网络体系由于在其形成过程中产生特殊的物理拓扑结构,使得该体系是一种永久缠结在一起的聚合物"合金"[1]。同时,由于构成该体系的聚合物组分往往不相容或部分相容,在其形成     

Preparation of a nanosilica‐modified negative‐type acrylate photoresist

A new type of negative photoresist, which incorporated nanosized silica into a photosensitive acrylic resin, was developed. First, free‐radical polymerization was employed to synthesize the acrylic resin, poly[methyl methacrylate/methacrylic acid/3‐(trimethoxysilyl) propyl methacrylate], and then a silica precursor, prepared by hydrolysis and condensation of tetraethoxysilane in a sol–gel process, was introduced into the as‐formed resin solution. After the addition of photosensitive monomers and photoinitiators, a negative‐type organic–inorganic photoresist was produced. The morphology of the UV‐cured photoresist, as observed by field emission scanning electron microscopy, indicated that the size of the silica domain in the material could be reduced from 300 to about 50 nm by appropriate dosage of 3‐(trimethoxysilyl) propyl methacrylate. Thermogravimetric analysis, dynamic mechanical analysis, differential scanning calorimetry, and thermal mechanical analysis were used to evaluate the thermal and dimensional stabilities of the cured photoresists. It was found that the thermal decomposition temperature and glass‐transition temperature increased, whereas the thermal expansion coefficients before and after the glass transition decreased, with increasing silica content. The incorporation of 3‐(trimethoxysilyl) propyl methacrylate also enhanced the thermal and dimensional stabilities; however, the level of enhancement was moderate for the thermal decomposition temperature and thermal expansion coefficient and low for the glass‐transition temperature. In addition, a photoresist coated on a copper substrate demonstrated high hardness (5H) and strong adhesion (100%) with a resolution of 30 μm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Surface modification of polymethyl methacrylate by graft copolymers

Summary Graft copolymers composed of poly(methyl methacrylate) branches and different backbones of poly(fluoroalkyl acrylate(FA)-co-methyl methacrylate(MMA)), poly (hydroxyethyl methacrylate(HEMA)-co-MMA), and poly(FA-co-HEMA) were prepared by macromonomer technique to study their application as a surface modifier for PMMA films. Contact angle of water droplet on PMMA film specimens containing various amounts of these graft copolymers cast on glass slides from THF solution was found to change considerably with the graft copolymer concentration, depending on their backbone component. And there was considerable difference in contact angle between air and glass side of the film surfaces. These results were considered in terms of the surface accumulation of graft copolymers during the solvent evaporation.     

Wettability and adhesion studies of plasma-treated plastic substrates for gelatin holograms

The feasibility study of using polycarbonate and poly(methyl methacrylate) substrates treated with the oxygen plasma for dichromated gelatin holograms is reported. The contact angles of water on both treated and untreated substrates were measured to indicate the wettability of substrate surfaces. An appreciable increase in adhesion between the dichromated gelatin film and the polycarbonate substrate after the oxygen plasma treatment was demonstrated.     

Synthesis of epoxy resin–silica nanocomposites provided from perhydropolysilazane as a curing reagent and the precursor of silica domain

Epoxy resin–silica nanocomposites with spherical silica domains with 29.0 nm in diameter in an epoxy resin matrix were synthesized from Bisphenol‐A type epoxide monomer, 2,2‐bis(4‐glycidyloxyphenyl)propane (DGEBA), and perhydropolysilazane (PHPS, ? [Si₂? NH]_n? ). The volume fraction of silica domain in the composite varied from 5.4 to 37.8 vol % by varying the feed ratio of PHPS to the epoxide monomer. The reaction mechanism of epoxy group and PHPS was investigated by using glycidyl methacrylate as a model compound of the epoxy monomer by ¹H‐nucular magnetic resonance and Fourier transform infrared spectrometry. Ammonia gas provided by the decomposition of PHPS with moisture converted PHPS to silica and cured the epoxy monomer. The curing of epoxy monomer preferably proceeded than the conversion of silica. The addition of 1,4‐diaminobutane drastically accelerated the rate of curing; white and hard epoxy resin–silica nanocomposites were obtained. The good thermal stability of the composite prepared with DGEBA/PHPS/1,4‐diaminobutane was observed by thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Plastic and fracture behavior of nanosilica‐filled poly(methyl methacrylate)

The plastic and fracture behavior of ‘model’ hybrid materials based on methyl methacrylate and methacryloxypropyl‐grafted nanosilica was investigated. A four‐step synthesis procedure allowed preparation of transparent nanosilica–poly(methyl methacrylate) networks of well‐defined architecture, of variable particle diameter, volume fraction of particles, number of methacryloyl units grafted per surface unit of silica particles and nature of the grafting agent. Plasticity behavior was investigated through compression tests. The evolution of yield stress with volume fraction of fillers can be understood by taking into account the undeformability of particles and using the geometrical Kerner approach. The reduction of plastic flow plateau by a substantial strain hardening was imputed to the presence of crosslinks on the particles. Fracture properties were deduced from three‐point bending experiments on notched samples. The effects on toughness of filler incorporation are tentatively related to plasticity and to the presence of crosslinks. Copyright © 2006 Society of Chemical Industry     

Interpenetrating polymer networks. II. Sunlight-induced polymerization of multifunctional acrylates

Protective coatings and glass laminates have been readily obtained by sunlight-curing of acrylate monomers dispersed in a poly(methyl methacrylate) matrix or in a styrene–butadiene rubber, in the presence of an acylphosphine oxide photoinitiator. The polymerization reaction was followed by infrared spectroscopy and by gel fraction measurements and was shown to proceed extensively within minutes. As expected, the inhibitory effect of atmospheric O₂ on such radical-initiated reactions was less pronounced in solid than in liquid samples. The monomer, photoinitiator, and plasticizer concentrations were found to have a strong influence on the rate of polymerization, the final degree of conversion, and the hardness of the sun-cured polymer. The adhesion of the cured coating on glass was substantially improved by the addition of an acrylate-grafted organosol silica. To produce strongly adhesive glass laminates, a photocurable acrylate resin was poured between two coated glass plates and exposed to sunlight for a few seconds. The same formulation can serve as a light-sensitive quick setting glue to bond glass to a variety of materials [polycarbonates, poly(vinyl chloride), aluminium, and steel]. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2269–2282, 1998     

Physical,chemical, and dyeing properties of Bombyx mori silks grafted by 2‐hydroxyethyl methacrylate and methyl methacrylate

To obtain silk weight gain and to improve silk properties, Bombyx mori silks were grafted with either 2‐hydroxyethyl methacrylate (HEMA) or methyl methacrylate (MMA). The moisture regain of the HEMA‐grafted and MMA‐grafted silks depended on the hydrophilicity of the used monomers. The acid and alkaline resistances of the HEMA‐grafted and MMA‐grafted silks were clearly improved. Both commercial synthetic dyes, that is, acid and reactive dyes, and a natural dye extracted from turmeric, with potassium aluminum sulfate as a mordant, were used in this study. The results suggested that the dye uptake increased in the presence of poly(2‐hydroxyethyl methacrylate) or poly(methyl methacrylate) in the silk fibroin structures when acid and curcumin dyes were used. The washfastness level of the HEMA‐grafted silk dyed by acid and reactive dyes was similar to that of the degummed silk. However, the colorfastness to washing of the MMA‐grafted silk dyed by an acid dye was improved when the polymer add‐on concentration was 65%. In addition, the washfastness for both grafted silks was improved when they were dyed with natural curcumin dyestuff. The acid and alkaline perspiration fastness properties remained unchanged for the HEMA‐grafted and MMA‐grafted silks when acid, reactive, and curcumin dyes were applied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Thermomechanical properties and morphology of interpenetrating polymer networks of polyurethane–poly(methyl methacrylate)

Interpenetrating networks (IPNs) of polybutadiene‐based polyurethane (PU) and poly(methyl methacrylate) (PMMA) were synthesized. The effect of the incorporation of 2% glycidyl methacrylate (GMA) and 2‐hydroxyethyl methacrylate (2‐HEMA) on the thermal, mechanical, and morphological properties of IPNs was investigated. Both 2‐HEMA and GMA led to improvements in these properties. However, 2‐HEMA‐containing IPNs showed somewhat better tensile strength, elongation, and damping characteristics. The morphology of IPNs containing 2‐HEMA showed better mixing of the components. The improvement in the properties was observed for up to 40% PMMA in the IPNs. Differential scanning calorimetry thermograms showed the presence of three glass transitions. The third glass‐transition temperature was explained by possible grafting of methyl methacrylate onto PU. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1576–1585, 2002     

Dynamic‐mechanical behavior of hydrophobic–hydrophilic interpenetrating copolymer networks

Sequential interpenetrating polymer networks (IPNs) were prepared by free‐radical polymerization. One of the components of the IPN was a poly(butyl acrylate) (PBA) network, and the other one was a poly(methyl methacrylate‐co‐hydroxyethyl methacrylate) copolymer network. Dynamic‐mechanical experiments show that the IPNs are phase separated: two main α relaxations occur in all samples, the low temperature one corresponding to the PBA network and that appearing at higher temperature due to the copolymer network. The latter shows a shape analogous to a pure poly(hydroxyethyl methacrylate) (PHEMA) network independently of the copolymer composition. The influence of water absorption on the dynamic‐mechanical spectrum shows that only a small amount of water reaches the butyl acrylate segments. The dependence of the mechanical behavior of the poly(methyl methacrylate‐co‐hydroxyethyl methacrylate) copolymer networks with the copolymer composition has been also analyzed. POLYM. ENG. SCI., 46:930–937, 2006. © 2006 Society of Plastics Engineers     

Preparation of zirconia loaded poly(acrylate) antistatic hard coatings on PMMA substrates

Zirconia (ZrO₂) nanoparticles were synthesized by hydrolysis and condensation of zirconium‐n‐propoxide (ZNP) in 1‐propanol at the presence of methacrylic acid (MA), serving as a chelating agent for ZNP. The formed nanoparticles were chemically modified by the UV‐curable coupling agent, 3‐(trimethoxysilyl)propyl methacrylate (MSMA). The modified particles were then crosslinked with the hexa‐functional monomer, dipentaerythritol hexaacrylate (DPHA), to produce transparent antistatic hard coatings on poly(methyl methacrylate) (PMMA) substrates. Sizes of the modified particles, as determined by the dynamic light scattering technique, fell over a small range of 2–20 nm. Chemical analyses of the particles and the coatings were performed using FTIR and/or solid ²⁹SiNMR spectroscopy. Surface resistivities of the coatings were measured, and the results indicated that with inclusion of 10 wt % modified zirconia, surface resistivity of ～10⁹ Ω/sq could be achieved, which amounted to ～6 order magnitude lower than that of the particle‐free polymeric binder. Furthermore, this antistatic coating was very hard with pencil hardness of 8–9H, and attached perfectly to the PMMA substrate according to the peel test. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42411.     

Transparent,Lightweight, and High Strength Polyethylene Films by a Scalable Continuous Extrusion and Solid‐State Drawing Process

The continuous production of transparent high strength ultra‐drawn high‐density polyethylene films or tapes is explored using a cast film extrusion and solid‐state drawing line. Two methodologies are explored to achieve such high strength transparent polyethylene films; i) the use of suitable additives like 2‐(2H‐benzotriazol‐2‐yl)‐4,6‐ditertpentylphenol (BZT) and ii) solid‐state drawing at an optimal temperature of 105 °C (without additives). Both methodologies result in highly oriented films of high transparency (≈91%) in the far field. Maximum attainable modulus (≈33 GPa) and tensile strength (≈900 MPa) of both types of solid‐state drawn films are similar and are an order of magnitude higher than traditional transparent plastics such as polycarbonate (PC) and poly(methyl methacrylate). Special emphasis is devoted to the effect of draw down and pre‐orientation in the as‐extruded films prior to solid‐state drawing. It is shown that pre‐orientation is beneficial in improving mechanical properties of the films at equal draw ratios. However, pre‐orientation lowers the maximum attainable draw ratio and as such the ultimate modulus and tensile strength of the films. Potential applications of these high strength transparent flexible films lie in composite laminates, automotive or aircraft glazing, high impact windows, safety glass, and displays.     

Surface segregation during injection molding of polycarbonate/poly(methyl methacrylate) blend

We investigated the distribution of the constituent polymers of an injection-molded product comprising a miscible blend of polycarbonate (PC) and low-molecular-weight poly(methyl methacrylate) (PMMA). We found that PMMA became localized at the surface without affecting the transparency of the product. As a result, the surface hardness was effectively enhanced by a small amount of PMMA. This technique can be used to produce an ideal plastic glass that has high transparency, mechanical toughness, and high surface hardness.