Effects of the surface modification of poly(amino acid)/hydroxyapatite/calcium sulfate biocomposites on the adhesion and proliferation of osteoblast‐like cells

In this study, we focused on the surface modification of a novel poly(amino acid) (PAA)/hydroxyapatite/calcium sulfate composite and the effect of its surface modification on cellular responses. The surface modification was performed by sandblasting (sample S2), calcium chloride ethanol saturated solution etching (sample S3), and formic acid etching (sample S4) followed by in vitro culturing of osteoblast‐like cells. The obtained results indicate that a new interface of the composite was formed during the modification, and the modified surface was changed with respect to its surface morphology by physical abrasion. The calcium chloride ethanol saturated solution etchant etched PAA selectively whereas forming rich calcium‐phosphate (Ca–P) apatite on the surface of S3. The formic acid etchant attacked the inorganic component without changing the PAA state. Cell attachment and cell proliferation were improved by the treatments of S2 and S3 in comparison with no treatment and the treatment of S4 © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42427.     

Surface modification of polypropylene by the entrapping method using the short‐chained stearyl‐alcohol poly(ethylene oxide) ether modifier

On the basis of the short‐chained modifier of stearyl‐alcohol poly(ethylene oxide) ether (AEO), an entrapping modification was carried out on the polypropylene (PP) surface for hydrophilic improvement. A swelling layer was confirmed locating in the amorphous region on the PP surface, from which the modifiers could penetrate into the surface. The AEO‐8 modifier achieved the optimal hydrophilic modification on the surface with a contact angle of 20.6° and modifier coverage of 19.2%. A microphase separation was speculated to occur between the poly(ethylene oxide) (PEO) chain of AEO and the PP substrate in the entrapping surface, after which surface‐enriched PEO chains could improve surface hydrophilicity, simultaneously, reserved stearyl chains in the surface could approach modifier fixation. Water immersion durability of the modified surface could be improved by establishing a covalent linkage in the surface‐fixed structure. This work gives more comprehensive insights in the entrapping modification on the semi‐crystalline PP surface based on the short‐chained and block modifier. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43607.     

Influence of processing condition and carbon nanotube on mechanical properties of injection molded multi‐walled carbon nanotube/poly(methyl methacrylate) nanocomposites

In this work, multi‐walled carbon nanotubes (MWCNT) and poly(methyl methacrylate) (PMMA) pellets were compounded via corotating twin‐screw extruder. The produced MWCNT/PMMA nanocomposite pellets were injection molded. The effect of MWCNT concentration, injection melt temperature and holding pressure on mechanical properties of the nanocomposites were investigated. To examine the mechanical properties of the MWCNT/PMMA nanocomposites, tensile test, charpy impact test, and Rockwell hardness are considered as the outputs. Design of experiments (DoE) is done by full factorial method. The morphology of the nanocomposites was performed using scanning electron microscopy (SEM). The results revealed when MWCNT concentration are increased from 0 to 1.5 wt %, tensile strength and elongation at break were reduced about 30 and 40%, respectively, but a slight increase in hardness was observed. In addition, highest impact strength belongs to the nanocomposite with 1 wt % MWCNT. This study also shows that processing condition significantly influence on mechanical behavior of the injection molded nanocomposite. In maximum holding pressure (100 bar), the nanocomposites show highest tensile strength, elongation, impact strength and hardness. According to findings, melt temperature has a trifle effect on elongation, but it has a remarkable influence on tensile strength. In the case of impact strength, higher melt temperature is favorable. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43738.     

Mechanical properties and stem cell adhesion of injection‐molded poly(ether ether ketone) and hydroxyapatite nanocomposites

A nanocomposite of poly(ether ether ketone) (PEEK) with 10 wt % hydroxyapatite (HA) was produced by extrusion and injection molding. Afterward, the samples were thermally treated. Thermal and short‐ and long‐term mechanical characterizations of the samples were made. The adhesion of human adipose stem cells (h‐ASCs) on the samples was also monitored. The ultimate tensile strength (UTS) and elastic modulus values of the nanocomposite were found to be much higher than those of trabecular bone. The impact strength of PEEK was not modified by HA; this suggested that there was no formation of large agglomerates of nanoparticles that could concentrate the stresses. With regard to fatigue life, both the thermally and nonthermally treated nanocomposites did not fail after 10⁶ cycles when maximum stresses of 30 and 50% of the UTS were applied, but they failed when the maximum applied stress was 75% of the UTS and behaved as cortical bone. After 5 days of culturing, the h‐ASCs had a higher proliferation in the nanocomposite than in pure PEEK because of the presence of HA. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41748.     

Synthesis of poly(butyl acrylate)‐poly(methyl methacrylate) core–shell nanomaterials of anti‐crease‐whitening properties

Core–shell nanomaterials of poly(butyl acrylate)‐poly(methyl methacrylate) were synthesized using a differential microemulsion polymerization method for being used as polyacrylate‐based optical materials, which meet the requirement of anti‐crease‐whitening and proper mechanical strength. The effects of reaction temperature and surfactant amount on the particle sizes, as well as the effect of reaction temperature on the conversion and solid content were investigated to reveal the dependence of the application properties on the reaction conditions. The spherical morphology of core–shell nanoparticles was also studied via transmission electron microscopy. The resulting polymers with a core–shell monomer ratio of butyl acrylate/methyl methacrylate at 32/10 (vol/vol) demonstrated the optimal balanced properties in the anti‐crease‐whitening and mechanical property, confirmed by the visible light transmittance measurement and the dynamic analysis of the viscoelastic properties of the synthesized core–shell nanomaterials. The smaller the particle size, the better the transparency of the resulting polymer films. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39991.     

Employment of ultrasonic waves for the preparation of PVA/TiO2‐BSA nanocomposites: Mechanical,thermal, and optical properties

The goal of this project is to obtain poly(vinyl alcohol) (PVA)/TiO₂‐bovine serum albumin (BSA) nanocomposite (NC) films in different weight percentages of modified TiO₂. For this purpose, to prevent the accumulation of nanoparticles (NPs) in the PVA matrix, the surface of the TiO₂ NPs was treated with the BSA molecules. To achieve this aim, ultrasonic waves were used as an environmentally friendly and green process that decrease the time of reactions, help better spreading of TiO₂ NPs and maintain dimensions of TiO₂ NPs in the nanoscale range. In the end, the features of the PVA/TiO₂‐BSA NC films were considered with a variety of techniques. The Fourier transform infrared spectroscopy, energy dispersive X‐ray, and X‐ray diffraction showed that the BSA was well placed on the surface of TiO₂ NPs. The thermal gravimetric analysis and UV‐visible results demonstrated that all the PVA/TiO₂‐BSA NC films have better thermal and optical properties than the pure PVA. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46558.     

Functionalization of carbon nanotubes with (3‐glycidyloxypropyl)‐trimethoxysilane: Effect of wrapping on epoxy matrix nanocomposites

In this work, multiwalled carbon nanotubes (MWCNT), after previous oxidation, are functionalized with excess (3‐glycidyloxypropyl)trimethoxysilane (GLYMO) and used as reinforcement in epoxy matrix nanocomposites. Infrared, Raman, and energy‐dispersive X‐ray spectroscopies confirm the silanization of the MWCNT, while transmission electron microscopy images show that oxidized nanotubes presented less entanglement than pristine and silanized MWCNT. Thickening of the nanotubes is also observed after silanization, suggesting that the MWCNT are wrapped by siloxane chains. Field‐emission scanning electron microscopy reveals that oxidized nanotubes are better dispersed in the matrix, providing nanocomposites with better mechanical properties than those reinforced with pristine and silanized MWCNT. On the other hand, the glass transition temperature of the nanocomposite with 0.05 wt % MWCNT‐GLYMO increased by 14 °C compared to the neat epoxy resin, suggesting a strong matrix–nanotube adhesion. The functionalization of nanotubes using an excess amount of silane can thus favor the formation of an organosiloxane coating on the MWCNT, preventing its dispersion and contributing to poor mechanical properties of epoxy nanocomposites. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44245.     

Effect of interfacial pretreatment on the properties of montmorillonite/poly(vinyl alcohol) nanocomposites

This work explores the factors that control the dispersion of exfoliated montmorillonite (MMT) in poly(vinyl alcohol) (PVOH) during solution blending and solvent evaporation. Nanocomposite films were prepared by solution blending of aqueous PVOH solutions with dilute suspensions of fully exfoliated MMT platelets (as confirmed by AFM). Dynamic light scattering (DLS) indicates that addition of MMT suspensions to PVOH solutions results in undesired particle aggregation and thus poor MMT dispersion in cast films (as evidenced by transmission electron microscopic images and gas permeation measurements). We believe that PVOH bridging induces MMT platelet aggregation. To counteract bridging aggregation, we explore the novel idea of pretreating the MMT surface with a small amount of compatible polymer prior to solution blending with PVOH. We hypothesize that “pretreating” the MMT platelet surfaces with adsorbed polymer in dilute suspensions will protect the platelets from bridging aggregation during solution blending and solvent evaporation. MMT/PVOH composite films have been prepared using low‐molecular‐weight PVOH as the pretreatment polymer; and low‐, medium‐, and high‐molecular‐weight PVOH as the matrix polymer. A PEO‐PPO‐PEO triblock copolymer (F108 from the Pluronics^® family) was also evaluated as the pretreatment polymer. DLS shows that pretreated MMT platelets are less susceptible to aggregation during blending with PVOH solutions. Results compare the crystalline structure, thermal properties, dynamic mechanical properties, gas permeability, and dissolution behavior of MMT/PVOH films incorporating untreated versus pretreated MMT. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41867.     

Durability of polylactide‐based polymer blends for injection‐molded applications

The durability of polylactide (PLA) blended with polycarbonate (PC) was assessed by exposure to conditions of elevated temperature and humidity over a period of several weeks. Mechanical performance, moisture absorption, chemical composition, and thermal properties were monitored as a function of continuous conditioning at 70°C and 90% relative humidity (RH). All PLA and PC/PLA blends showed significant moisture absorption and hydrolysis, resulting in degradation of properties. Furthermore, while the addition of PC was intended to improve the durability of the blend over neat PLA, it was found that the hydrolysis products of PLA accelerated the degradation of PC itself. This study shows for the first time the hydrolysis behavior of PC/PLA blends in an increasingly acid environment during heat and humidity conditioning. These injection‐molding grades of PLA‐based resins are currently not suitable for use in applications that require long‐term durability in environments subject to elevated temperature and humidity, such as automotive interiors. Further material formulation work is required before use in injection‐molded applications for automotive. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Selective localization of organophilic clay Cloisite 30B in biodegradable poly(lactic acid)/poly(3-hydroxybutyrate) blends

The influence of selective localization of the nanoclay Cloisite 30B on the morphological, thermal and thermo-mechanical properties of biodegradable poly(lactic acid)/poly(hydroxybutyrate) blends was evaluated in this work. For this, different compounds were obtained by adding the filler in a single phase or mixed with the two matrices simultaneously by melting processing. The simultaneous processing leads to a better dispersion of nanoparticles on the blend and generates a more homogeneous polymer interface, but the properties do not increase in relation to those that were processed in separate steps. For the blends obtained in separated steps, the polymeric domains and, consequently, the superficial tension between phases are better controlled by a nanolayer. Thus, the results obtained in this work indicate that better control of the polymeric interfaces can generate a more significant effect on the thermal and thermo-mechanical properties of nanostructured blends than just a good dispersion of the fillers.     

Interfacial polymerization of poly(2,5‐dimethoxyaniline) and its enhanced capacitive performances

The poly(2,5‐dimethoxyaniline) (PDMA) were synthesized through interfacial polymerization method using three various organic solvent/water reaction systems. As comparison with conventional chemical polymerized PDMA, the interfacial polymerization can produce uniform nanoparticular PDMA, especially for using high density (higher than water) solvent as organic phase. The capacitive performances of interfacial polymerized PDMA can be benefited from its uniform morphologies and loose packing structure. The specific capacitance of interfacial polymerized PDMA using carbon tetrachloride is 194 Fg^?1 at current density of 50 mA cm^?2, which has 59% enhancement over 122 Fg^?1 of conventional PDMA at the same current density. The energy density of interfacial polymerized PDMA is 39 Wh kg^?1 at current density of 5 mA cm^?2 and the power density is 28,421 W kg^?1 at current density of 50 mA cm^?2. The energy density has improvement in different extent as comparison with that of conventional PDMA. The enhanced capacitive performances can be attributed to the increased ionic conductivity induced by the loose molecular packing structure and uniform morphology produced by the interfacial polymerization process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40666.     

The properties (rheological,dielectric, and mechanical) and microtopography of spherical fullerene‐filled poly(arylene ether nitrile) nanocomposites

Poly (arylene ether nitrile)/fullerene (PEN/fullerene) nanocomposites were prepared by a facile solution‐cast method and the rheological, dielectric, mechanical, and morphological properties of the resulted nanocomposites were systematically studied and compared. Rheological studies showed PEN/fullerene nanocomposites percolation network formed at fullerene containing of 1.50 wt %, when the shear frequency was fixed at 0.1 Hz, the fitted rheological percolation threshold was about 1.55 wt %, very close to the experimental observations. The dielectric transaction occurs when the fullerene loading reached 1.50 wt %, that is very close to its rheological percolation threshold. At this point, PEN/fullerene nanocomposites also showed the optimal mechanical properties with a tensile strength of 93.6 MPa and modulus of 1951.5 MPa, which is increased by 27% and 15% compared with the pure PEN. SEM and TEM images have manifested the separate fullerene aggregated to fullerene bundles in PEN/fullerene nanocomposites, and the dispersion of fullerene bundles begin to go bad when the containing above 1.50 wt %. The PEN/fullerene nanocomposites can be widely used due to its excellent dielectric and mechanical performance. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40100.     

Highly hydrophobic hierarchical nanomicro roughness polymer surface created by stamping and laser micromachining

This article describes the design and fabrication of hierarchical nanomicrostructured polymer surfaces with high hydrophobicity. The nanoscale roughness is achieved by stamping a ZnO nanowire film into PDMS. Subsequently, microstructures with different periodicities are created in the stamped PDMS sample by direct laser writing using femtosecond pulses. With this approach, we were able to produce hierarchical surface morphologies, composed of nano and microscale structures that exhibit water contact angles larger than 160°. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42082.     

Fabrication and surface characterization of electrosprayed poly(L‐lactide) microspheres

Electrospraying is a one‐step technique for fabricating polymeric microspheres/nanospheres, and the surface characterization of polymeric microspheres fabricated under high voltage is different from an emulsion method. In this study, biodegradable poly(l ‐lactide) (PLLA) microspheres were successfully fabricated by electrospraying, and electrospraying parameters were used to investigate the size and ζ potential of the electrosprayed PLLA microspheres. The results demonstrate that electrospraying was a one‐step method for fabricating monodispersed PLLA microspheres with a size of 1.92 ± 0.35 μm and that the enrichment of methyl groups on the surface of the microspheres contributed to the strong hydrophobicity of electrosprayed PLLA microspheres. Of all the electrospraying parameters investigated, the size and ζ potential of the PLLA microspheres increased with increasing solution concentration and flow rate and decreased with increasing injection voltage and collecting distance. The results provide a theoretical basis for preparing electrosprayed polymeric microspheres as drug carriers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Prediction of long‐term mechanical properties of PVDF/BaTiO3 nanocomposite

Low elastic modulus of polyvinylidene fluoride (PVDF) is a major drawback that can be compensated by adding nanoparticles. This work reports the long‐term mechanical behavior of PVDF nanocomposite containing BaTiO₃ nanoparticle that is evaluated by creep test. The nanocomposite morphology was characterized by scanning and transmission electron microscopy techniques. The dynamic mechanical analysis (DMA) was employed to study the viscoelastic behavior of nanocomposite in a wide range of temperatures and frequencies. According to the creep tests, nanocomposite reduced the rate of the creep compliance at different temperatures. Moreover, the creep compliance for the nanocomposite sample decreased slightly in comparison with neat PVDF. Comparing the Burger's model and experimental results, the elastic and viscous parameters revealed the exactly opposite behavior with increasing temperature. The effect of frequencies on storage moduli of samples was investigated based on time–temperature superposition (TTS) method. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40596.     

Multifunctional polyaniline–tin oxide (PANI–SnO2) nanocomposite: Synthesis,electrochemical, and field emission investigations

Synthesis of PANI–SnO₂ nanocomposite has been performed using a simple two step chemical oxidative polymerization route. The structural, morphological and chemical properties of the as‐synthesized PANI–SnO₂ nanocomposite have been revealed by various characterization techniques such as SEM, TEM, XRD, FTIR, and XPS. Interestingly the as‐synthesized PANI–SnO₂ nanocomposite exhibits supercapacitance value of 721 F g^?1 with energy density 64 Wh kg^?1, which is noticed to be higher than that of pristine SnO₂ and PANI nanostructures. Furthermore, the galvanostatic charge–discharge characteristics revealed pseudocapacitive nature of the PANI–SnO₂ nanocomposite. The estimated values of charge transfer resistance and series resistance estimated from the Nyquist plot are found to be lower. Along with the supercapacitive nature, PANI–SnO₂ nanocomposite showed promising field emission behavior. The threshold field, required to draw emission current density of 1 μA/cm², is observed to be 0.90 V/μm and emission current density of 1.2 mA/cm² has been drawn at applied field of ～2.6 V/μm. The emission current stability investigated at preset values of 0.02 and 0.1 mA/cm² is observed to be fairly stable over duration of more than 3 h. The enhanced supercapacitance values, as well as, the promising field emission characteristics are attributed to the synergic effect of SnO₂ nanoparticles and PANI nanotubes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41401.     

Interfacial influence on mechanical properties of polypropylene/polypropylene‐grafted silica nanocomposites

Three types of polypropylene‐grafted silica (PGS‐2 K, PGS‐8 K and PGS‐30 K) with different grafting chain lengths were prepared. After melt‐blending PGS with polypropylene (PP), we studied the PP/PGS interface properties and the influence of PP/PGS interfaces on mechanical properties of nanocomposites. The strong matrix/particle interface was observed in PP/PGS‐30 K nanocomposites with 5 wt % particle loading as evidenced by 2.5 °C increased glass transition temperature (T_g) compared with neat PP, whereas the weak matrix/particle interface was observed in PP/PGS‐2 K nanocomposites with decreased T_g. The variations in the matrix/particle interfacial strength lead to a transition in the yield stress of nanocomposites. Compared with the unfilled PP, the yield stress of the PP/PGS‐2 K nanocomposites is decreased by 0.7 MPa, and the yield stress of the PP/PGS‐30 K nanocomposites is enhanced by 1.4 MPa. In addition, benefiting from good dispersion, the PP/PGS‐masterbatch nanocomposites with a strong matrix/particle interface not only exhibit increased Young's modulus and yield stress, but also the strain at break remains in line with the unfilled PP, which is in contrast to the conventional wisdom that the gain in modulus and strength must be at the expense of the decreased break strain. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45887.     

Effects of water on the long‐term properties of Bis‐GMA and silylated‐(Bis‐GMA) polymers

Bis‐GMA (2,2‐bis‐[4‐(2‐hydroxy‐3‐methacryloxypropoxy)phenyl]propane) is a viscous hygroscopic monomer which is used with triethyleneglycol‐dimethacrylate (TEGDMA) for dental restorations. Bis‐GMA was silylated with dimethyl‐isopropyl‐siloxane and further polymerized in order to increase water resistance and viscosity. The viscosity of the silylated monomer, Sil·Bis‐GMA, was 50 times lower than that of the parent monomer. After 1 month in water, poly(Bis‐GMA/TEGDMA) absorbed 2.6% water and the silylated polymer, poly(Sil·Bis‐GMA), only 0.56%. During this process water extracted residual monomer from each polymer. The behavior of water sorption and desorption as a function of time in poly(Sil·Bis‐GMA) was completely different from that shown by poly(Bis‐GMA/TEGDMA). The difference is discussed in terms of diffusion coefficients. Initially, water advancing contact angles (θ_ADV) were 75° and 95°, respectively. After 1 month in water both polymers showed a reduction of about 20° in θ_ADV. In poly(Bis‐GMA/TEGDMA), the reduction in θ_ADV obey to water absorption and bulk plasticization; it showed a reduction of 15°C in glass transition temperature, T_g. In contrast, the reduction in θ_ADV in poly (Sil·Bis‐GMA) obeyed to water adsorption and reorientation of the molecules at the surface in contact with the water phase; it only showed a change of 2°C in T_g. Contact angle hysteresis provided further evidence about plasticization. According to our results poly(Sil·Bis‐GMA) is more stable in water than poly(Bis‐GMA/TEGDMA). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermal,mechanical, and rheological properties of poly(ε‐caprolactone)/halloysite nanotube nanocomposites

Naturally available halloysite nanotubes (HNTs) with hollow nanotubular structures were used as reinforcement in poly(ε‐caprolactone) (PCL). The PCL/HNT nanocomposites were prepared by melt mixing the polymer with as‐received HNTs up to 10 wt % in an internal batch mixer. Transmission electron microscopy analysis indicated that the HNTs were dispersed uniformly on the nanoscale throughout the PCL matrix. Differential scanning calorimeter studies revealed that the PCL crystallinity was decreased in the nanocomposites, and the HNTs dispersed in the PCL matrix led to an increase in the non‐isothermal crystallization temperature of the PCL. Tensile and dynamic mechanical tests showed great enhancement in strength and stiffness at low HNT content, while still maintaining the ductility of the PCL. The glass transition temperature (T_g) of the pristine PCL was substantially increased with increase in filler loading, which indicates good reinforcing effect imparted by the addition of HNT. Melt rheological studies revealed that the nanocomposites exhibited strong shear thinning behavior, and a percolated network of HNT particles was formed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Ultraviolet–ozone surface cleaning of injection‐molded,thermoplastic microcantilevers

Ultraviolet–ozone (UVO) is used for the cleaning of labware from organic contamination and includes sterilization, surface roughening, and activation. A range of polymers has been treated without major effects on surface topography and surface chemistry. Even for those, which are subject to physical and chemical aging, a trade‐off between damages and surface cleaning was often found. This communication presents a comprehensive overview on how to UVO‐treat selected polymers known from applications in biology and medicine, in particular microcantilevers used for biosensing. The study provides well‐defined thresholds below which degradation and surface damages are avoided. The impact of UVO treatments on the surface and bulk properties of the injection‐molded polymers was examined by means of differential scanning calorimetry and Fourier transform infrared spectroscopy measurements. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41922.