Relation between hydrophilicity and cell culturing on polystyrene Petri dish modified by ion‐assisted reaction

Polystyrene Petri dishes were modified by an ion‐assisted reaction to supply a suitable surface for culturing cells. Wettability was measured by a contact anglometer after surface modification of polystyrene. Contact angles of water on the polystyrene were not reduced much by Ar⁺ ion irradiation only, but dropped rapidly to a minimum of 19°, when polystyrene surface was modified by Ar⁺ ion irradiation with flowing oxygen gas. X‐ray photoelectron spectroscopy analyses showed that hydrophilic groups were formed on the surface of polystyrene by a chemical reaction between unstable chains induced by the ion irradiation and the blown oxygen gas. Newly formed hydrophilic groups were identified as C O,  (CO) and  (CO) O bonds. The influence of the ion beam modification in growth of the rat pheochromocytoma cells was investigated. The results showed exclusively preferential cell growth in the polystyrene Petri dish that was treated by the ion‐assisted reaction. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 41–46, 1999     

Surface modification of polytetrafluoroethylene by Ar+ irradiation for improved adhesion to other materials

A surface of thin square polytetrafluoroethylene (PTFE) samples (1 × 1 × 0.2 cm³) was irradiated with Ar⁺ at 1 keV with varying ion dose from 5 × 10¹⁴ to 1 × 10¹⁷ ions/cm² with and without an oxygen environment. The irradiated surface of the samples was examined by scanning electron microscopy (SEM) for surface textural changes and x-ray photoelectron spectrometry (XPS) for changes in chemical structure. A wettability test was conducted on the irradiated surface of PTFE samples by water droplets. A Scotch ™ tape adhesion test, after a thin film of Cu or Al was evaporated on the irradiated surface, and a tensile test after irradiated samples were glued to sample holders by an adhesive glue (Crystal Bond) was also run. The SEM micrographs showed increasing roughness with fiber forest-like texture with increasing ion dose. The Ar⁺ with an O₂ environment produced finer and denser fiber forest-like texture than that without O₂. The high-resolution XPS spectra showed decreased intensity of the F1s peak and formation of the O1s peak when irradiated with the O₂ environment. The increase of the O1s peak may be attributed to the reaction of oxygen atoms and the free radicals created by Ar⁺ bombardment. The wettability of water droplets on the irradiated surfaces was found to be inversely proportional to the surface roughness. Adhesion tests were conducted on 2000 Å thick Al or Cu film. Full detachment of the metal films was observed when PTFE samples were not modified. Partial detachment of the Al film occurred when PTFE was irradiated without the O₂ environment, regardless of ion dose. No detachment of the film occurred when PTFE was irradiated with the O₂ environment with the ion dose exceeding 1 × 10¹⁶ ions/cm². Partial detachment of Cu film was observed with or without the O₂ environment when the ion dose was 5 × 10¹⁴ ions/cm². No detachment occurred with or without the O₂ environment when the ion dose was 1 × 10¹⁵ ions/cm² or greater. The tensile test showed that adhesion of an adhesive cement (Crystal Bond) to the irradiated PTFE samples increased significantly with increasing ion dose up to 1 × 10¹⁶ ions/cm². Possible mechanisms for the improved adhesion are given. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1913–1921, 1997     

Improving adhesion between thin chromium film and polyimide substrate by Ar+ irradiation

Ar⁺ irradiation and annealing at an elevated temperature are used to improve the adhesion of deposited Cr thin films by vacuum evaporation onto polyimide (PI) substrates. The Ar⁺ ions of 50 and 200 keV and various Ar⁺ doses ranging from 1 × 10¹³ to 2 × 10¹⁶ ions/cm² are chosen for the experiments, after many preliminary trials. The surface analyses are conducted employing Rutherford Backscattering Spectroscopy (RBS), Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM). Ar⁺ irradiation produces an interfacial layer of about 100 Å (10 nm) thick in which Cr particles and PI molecules are physically mixed and chemically bonded. The chemical bonds of Cr? O and a trace of Cr?C are observed by XPS and FTIR. Impact-wear tests are also conducted in order to determine the effects of the Ar⁺ irradiation on the wear property of a Cr/PI system. A significant increase in the property is observed and the increase appears to be a function of the degree of adhesion of the Cr film to the PI substrate.     

Ion beam ablation of polytetrafluoroethylene

Polytetrafluoroethylene (PTFE) was irradiated with 300 keV Ar⁺ ions to the fluences of 1 × 10¹⁴ to 1 × 10¹⁶ cm⁻²; the PTFE structural changes induced by the ion irradiation were studied by X-ray diffraction and UV–vis and IR spectroscopies. The electrical conductivity of the ion beam modified PTFE was also investigated using the standard technique, and the alterations of the surface polarity were determined by contact angle measurements. The ion irradiation leads to intensive PTFE ablation due to the breaking of the C—C bonds in the polymer molecular chains and due to the production and liberation of the molecular fragments C_xF_y. In contrast to other polymeric materials, the irradiated PTFE carbonizes to a lesser extent and the observed irradiation induced increase of the electrical conductivity is also not significant. In-coming ions cause a reduction of the crystalline phase content in the PTFE samples. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 69: 1257–1261, 1998     

Thermoresponsive surface prepared by atom transfer radical polymerization directly from poly(vinylidene fluoride) for control of cell adhesion and detachment

Thermoresponsive surface was prepared from commercial poly(vinylidene fluoride) (PVDF) films via surface‐initiated atom transfer radical polymerization. The direct initiation of the secondary fluorinated site of PVDF facilitated grafting of the N‐isopropylacrylamide (NIPAAm) monomer. The PVDF surfaces grafted with poly(N‐isopropylacrylamide) [P(NIPAAm)] were characterized by X‐ray photoelectron spectroscopy. Kinetics study revealed that the P(NIPAAm) chain growth from the PVDF surface was consistent with a “controlled” process. The temperature‐dependent swelling behavior of the surfaces in aqueous solution was studied by atomic force microscope. At 37°C [above the lower critical solution temperature (LCST, about 32°C) of NIPAAm], the seeded cells adhered and spread on the NIPAAm grafted PVDF surface. Below the LCST, the cells detached from the P(NIPAAm)‐grafted PVDF surface spontaneously. The thermoresponsive surfaces are potentially useful as stimuli‐responsive adhesion modifiers in the biomedical fields.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Comparative study of gamma and ion beam irradiation of polymeric nanocomposite on electrical conductivity

Poly(vinyl alcohol) (PVA) was used to prepare nanocomposites of multi‐wall carbon nanotubes (MWCNT) and functionalized carbon nanotubes (MWCNT‐NH₂) in existence of 2‐carboxyethyl acrylate oligomers (CEA). Radiation‐induced crosslinking of the prepared matrix was carried out via gamma and ion beam irradiation. A comparative study of gamma and ion beam irradiation effect on the electrical conductivity of nanocomposite was conducted. The gelation of the gamma irradiated matrix outperforms the ion beam irradiated matrix. The order of gelation is PVA > (PVA/CEA) > (PVA/CEA)‐MWCNT > (PVA/CEA)‐MWCNT‐NH₂. There is a significant reduction in the swelling of the nanocomposite. The formation of nanocomposites was confirmed by scanning electron microscopy, energy‐dispersive X‐ray (EDX) and FTIR examinations. The direct current electrical properties of PVA/nanocomposites are examined at room temperature by applying electric voltage from 1 to 20 V. The results revealed that the electrical conductivity is increased by adding the carbon nanotubes and irradiation by gamma and ion beam. At an applied electric voltage 20 V, in the electrical conductivity of the unirradiated PVA was from 9.20 × 10^?8 S cm^?1. After adding MWCNT an increase up to 4.70 × 10^?5 S cm^?1 was observed. While after ion beam irradiation, a further increase up to 9.30 × 10^?5 S cm^?1 was noticed. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46146.     

Surface treatment of CFRP composites by Ar+ irradiation to improve bonding strength between aluminum and CFRP composites

The effect of surface treatment of carbon fiber reinforced plastic (CFRP) composites on the T-peel strength and the shear strength between CFRP and aluminum panels was studied. The surface of the composite panel was treated with Ar⁺ irradiation under oxygen environment. The optimal Ar⁺ ion dose was determined by measuring the changes of contact angle and surface energy as a function of ion dose. T-peel tests and SLS tests were performed using irradiated CFRP/aluminum specimens and unirradiated CFRP/aluminum specimens to determine the treatment effect by Ar⁺ irradiation under oxygen environment on the T-peel strength and shear strength of CFRP/aluminum composites. The results showed that contact angle on the surface of the composite panel was reduced from ∼80° to ∼8° and the surface energy increased from 31 ergs/cm² to 72.4 ergs/cm² with an ion dose of 10¹⁷ ions/cm². T-peel strength and shear strength are significantly affected by the surface treatment of composite panel. T-peel strength and shear strength improved 650% and 56%, respectively, when the treatment was made with an ion dose of 10¹⁶ ions/cm². SEM examination showed that the improvement of bonding strength was attributed to the uniform spread and fracture of epoxy adhesive.     

Dielectric properties of irradiated polymer/multiwalled carbon nanotube and its amino functionalized form

The polymer/multiwalled carbon nanotube [poly(vinyl alcohol) (PVA)/carboxyethyl acrylate (CEA)]‐multiwalled carbon nanotube (MWCNT) and its amino functionalized (PVA/CEA)‐MWCNT‐NH₂ nanocomposite samples were successfully synthesized by the chemical method in the form of films. The samples were irradiated with gamma‐ray doses of 50 and 100 kGy and with ion beam fluence of 2.5 × 10¹⁸ and 3.75 × 10¹⁸ ions cm^?2. The prepared nanocomposite samples were characterized using X‐ray diffraction and thermogravimetric analysis. The X‐ray diffraction and thermogravimetric analysis confirm the existence of the chemical crosslinking occurred in the polymer compositions. The AC electrical conductivity, electrical modulus, dielectric constant, and dielectric loss in the frequency range 10²–10⁶ Hz are measured at room temperature. The electrical conductivity is increased with MWCNT doping, gamma‐irradiation, and by ion beam irradiation. A comprehensive analysis of the results revealed that dielectric properties are improved due to the induced physicochemical changes and conductive networks induced by ion beam irradiation. The behavioral effect of these embedded nanoparticles in a PVA matrix on the microstructural, dielectric, and electric properties is analyzed for possible device applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46647.     

Study of surface chemical changes in PVDF irradiated by 1.3 MeV electrons

Summary The chemical changes that occur on the surface of poly(vinyliden fluoride) (PVDF) irradiated with 1.3 Mev electrons at doses up to 30 MGy, were studied by X–ray photoelectron spectroscopy (XPS) and by infrared spectroscopy (FTIR) in the horizontal attenuated total reflectance mode (HATR) and in the transmission mode. The wetability of the surface before and after irradiation was measured by dynamic contact angle measurements.The C 1s structure in XPS reveals that as a result of irradiation, the –CF₂– related peak practically disappears. The remaining C 1s peak is mainly associated with C=C bonds in the heavily cross–linked carbon structure produced as a result of irradiation. FTIR spectra are consistent with the XPS observations. The irradiated films showed improvement in the oxidation and wetability of the surface.     

Pt and Sn Doped Sputtered CeO2 Electrodes for Fuel Cell Applications

The interaction of Pt with CeO₂ layers was investigated by using photoelectron spectroscopy. Thirty‐nanometre‐thick Pt and Sn doped CeO₂ layers were deposited simultaneously by rf‐magnetron sputtering on a Si(001) substrate and a carbon diffusion layer of a polymer membrane fuel cell by using a composite CeO₂–Pt–Sn target. The laboratory XPS and synchrotron radiation soft X‐ray and hard X‐ray photoemission spectra showed the formation of cerium oxide with completely ionised Pt^2+,4+ species, and with Pt⁴⁺ embedded in the film bulk. Hydrogen/air fuel cell activity measurements normalised to the amount of Pt used revealed high specific power of up to 5.4 × 10⁴ mW mg^–1 (Pt). The activity of these materials is explained by the strong activity of embedded Ptⁿ⁺ cations.     

Oxygen vacancy enhanced room temperature ferromagnetism in Ar+ ion irradiated WO3 films

Room-temperature ferromagnetism in WO₃ films was enhanced by 130 keV Ar⁺ ion irradiation. The X-ray diffraction (XRD) and Raman measurements not only confirmed the monoclinic phase of the irradiated WO₃ films, but also showed that oxygen vacancy (V_O) defects were formed. The analysis of photoluminescence spectra strongly reconfirmed the presence of oxygen vacancy. X-ray photoelectron spectroscopy (XPS) measurements revealed that the contents of V_O and induced W⁵⁺ ions increase with increasing irradiation fluence and rich W⁵⁺-V_O defect complexes in the irradiated WO₃ films were formed. Further, the magnetic measurements exhibited a 2-fold enhancement in the saturation magnetization at the largest fluence of 3 × 10¹⁶ ions/cm². At lower irradiation fluence, a bound magnetic polaron model was proposed to reveal the ferromagnetic exchange coupling resulting from overlapping of V_O⁺ and V_O⁺⁺ defect states, and 5d¹ states of W⁵⁺. At high irradiation fluence, the carrier concentration reaches 1.02 × 10²⁰/cm³ and carrier-mediated exchange interactions result in the film's ferromagnetism.     

Degradation of polyimide by implantation with Ar+ ions

Polyimide (PI) samples were irradiated with 200 keV Ar⁺ ions to fluences from 5 × 10¹³−1 × 10¹⁷ cm⁻² and the concentration depth profiles of implanted Ar atoms as well as of carbon and oxygen atoms of the polymer matrix were determined using the Rutherford backscattering technique. The surface polarity, sheet resistivity, and thermoelectric power of PI samples were also determined as a function of the ion fluence and temperature. As a result of the ion irradiation, the polyimide surface layer is depleted of oxygen and enriched by carbon. The sheet resistivity exhibits a minimum at the ion fluence of 5 × 10¹⁶ cm⁻² and the temperature dependence of the sheet resistivity indicates the semiconducting character of irradiated PI and the variable range hopping mechanism of charge transport. The thermoelectric power of the PI samples irradiated to high fluences is small, of the order of μV/K, and independent of temperature. This behavior is typical for metals. The simultaneous appearance of metal and semiconducting properties is probably due to the complex structure of the PI surface layer modified by the ion irradiation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 723–728, 1997     

Preparation and characterization of proton exchange membrane based on polyphosphoric acid modified by PVDF‐HFP

A polyphosphoric acid functionalized proton exchange membrane (PEM) was prepared by a ring opening reaction using the epoxycyclohexylethyltrimethoxysilane (EHTMS) and amino trimethylene phosphonic acid (ATMP) as raw materials and was modified by poly(vinylidene fluoride)–hexafluoro propylene (PVDF‐HFP). The structure of the membranes was characterized by Fourier transform infrared and scanning electron microscopy. The X‐ray photoelectron spectroscopy explores the content of the elements in the membrane related to the ion exchange capacity value. The membranes’ properties including water uptake, swelling ratio, proton conductivity, and hydrolysis stability were studied. Performance tests show that when ATMP/EHTMS = 1/5, conductivity of the PVDF‐HFP modified PEMs increased from 0.83 × 10^?4 S cm^?1 at 20 °C to 9.53 × 10^?3 S cm^?1 at 160 °C, the swelling ratio of membranes decreased from 2.71% to 2.13%. The results indicate that the introduction of F atoms is beneficial to increase the proton conductivity and the dimensional stability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46737.     

Synthesis and sensitive properties of poly‐(bistriethylphosphine)‐platinum‐diethynylbenzene for organic vapor detection

Poly‐(bistriethylphosphine)‐platinum‐diethynylbenzene (Pt‐DEB) was synthesized by dehydrohalogenation reaction. X‐ray photoelectron spectroscopy (XPS), FTIR, and ¹H‐NMR spectra were used to identify the formation of Pt‐DEB target material. Sensitive properties of Pt‐DEB‐based quartz crystal microbalance (QCM) sensor to various organic vapors such as trichloromethane, tetrahydrofuran, acetone, isopropyl alcohol, ethanol, and methanol have been studied. The results show that Pt‐DEB has good reversibility, reproducibility, and linear sensitivity to organic vapors at room temperature. The sensitivity of Pt‐DEB (dissolved in CHCl₃) toward CHCl₃ is clearly higher than that toward other analytes, and a larger molecular weight of alcohol has a higher sensitivity response. The Pt‐DEB‐based QCM gas sensor shows low detection limits ranging from 1.0 to 3.56 ppm for the organic vapors and stable performance during a period of 30 days. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effect of pulsed laser irradiation on the SiC surface

The effect of a pulsed laser irradiation (Nd:YVO₄, 1064 nm) in air on the surface morphology and chemical composition of silicon carbide and on the adhesion with an epoxy adhesive was investigated. Scanning and transmission electron microscopies, atomic force microscopy, and X‐ray photoelectron spectroscopy revealed that the laser treatment reduced the contamination level of the surface and induced the formation of a silica‐based nanostructured columnar layer on the SiC surface. The mechanism for the formation of five different microstructural regions is described in this paper. In addition, the formation of a 5‐10‐nm‐thick graphite layer between the oxide layer and SiC was observed. The joining test with Hysol^® EA9321 showed that the nanostructured columnar silica layer was completely infiltrated by the adhesive, thus leading to a significant increase in the joined specific area and a mechanical interlocking at the adhesive/substrate interface. Nevertheless, the apparent shear strength of the joined SiC samples slightly decreased after the laser processing of the surfaces from about 42 MPa for lapped SiC to about 35 MPa for laser‐nanostructured SiC. The formation of the graphite layer was found to be responsible of the poor adhesion properties of the SiC surfaces modified by the laser radiation.     

Chemical grafting of curcumin at polyethylene terephthalate woven fabric surface using a prior surface activation with ultraviolet excimer lamp

Durable curcumin‐treated antibacterial polyethylene terephthalate (PET) fabrics (against Staphylococcus aureus) were produced by dyeing with curcumin after surface activation using vacuum ultraviolet excimer lamp at 172 nm. Surface change properties of the exposed fabrics were characterized by surface analysis methods such as wettability, atomic force microscopy, and X‐ray photoelectron spectroscopy. Results show an increase in surface hydrophilicity with a water contact angle of the PET fabric reaching 24° after 10 min excimer irradiation, which could be attributed to an increase in carboxyl group formation as confirmed by X‐ray photoelectron spectroscopy measurements. Varying concentrations of curcumin were immobilized onto untreated and vacuum ultraviolet‐irradiated PET samples using diffusion method at 90°C, and the treated fabrics characterized using K/S (color strength) values at 440 nm. K/S values increased when the PET surface was subjected to a prior excimer irradiation, because of grafting of curcumin at the PET surface. Increased excimer irradiation time increased grafting of curcumin because the inner fabric fiber surfaces were also more thoroughly treated. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Radiation Damage of LaMgAl11O19 and CeMgAl11O19 Magnetoplumbite

Studies of radiation damage in magnetoplumbite‐type LaMgAl₁₁O₁₉ and CeMgAl₁₁O₁₉ are reported. Ion irradiation was conducted on ceramic composites containing a LaMgAl₁₁O₁₉ phase at 500°C with 10 MeV Au⁺ ions and on ceramic composites containing CeMgAl₁₁O₁₉ phase at 800°C with 92 MeV Xe⁺ ions. The radiation response of these similar LnMgAl₁₁O₁₉ (Ln = La and Ce) hexaaluminate magnetoplumbite phases was evaluated using transmission electron microscopy (TEM) and X‐ray diffraction (XRD). LaMgAl₁₁O₁₉ was amorphized by 10 MeV Au ions with swelling of the structure within an approximate 2 μm radiation depth from the irradiation surface. CeMgAl₁₁O₁₉ did not amorphize after 92 MeV Xe‐ion irradiation, but ion track damage contrast is seen in approximately 5 μm of the irradiated depth. SRIM Monte‐Carlo simulations of nuclear displacements correlate with the experimental results.     

The effect of 60Co γ‐rays on the crystal structure,melting and crystallization behavior of poly(butylene succinate)

The results obtained for poly(butylene succinate) (PBS) after ⁶⁰Co γ‐ray irradiation, studied by wide‐angle X‐ray diffraction (WAXD), differential scanning calorimeter (DSC) and polarizing optical microscopy (POM), revealed that the degree of crystallinity, melting temperature and enthalpy decreased with increasing irradiation dose, but that the crystal structure of PBS did not vary when compared to non‐irradiated PBS. By using Scherrer equation, small changes occurred in the crystal sizes of L₀₂₀, L₁₁₀ and L₁₁₁. The spherulitic morphology of PBS was strongly dependent on irradiation dose and changed significantly at higher irradiation dosages. The crystallization kinetics of PBS indicated that the Avrami exponent (n) for irradiated PBS was reduced to 2.3, when compared to non‐irradiated PBS (3.3). Copyright © 2004 Society of Chemical Industry     

Ultra‐high dielectric constant of poly(vinylidene fluoride) composites filled with hydroxyl modified graphite powders

We provide a one‐step hydrothermal reaction to modify graphite powders (GPs) and prepare hydroxyl modified GPs/poly(vinylidene fluoride) (PVDF) composites which have excellent dielectric properties using high conductivity, low cost GPs as raw material. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) showed that hydroxyl groups had been introduced to the surface of GPs. Scanning electron microscopy (SEM) showed that the hydroxyl modified GPs had better dispersion in the polymer matrix than the GPs. An ultra‐high dielectric constant of more than 5.1 × 10³ (dielectric loss is about 3.0) was obtained for the hydroxyl modified GPs/PVDF near the percolation threshold at 1 kHz. The hydroxyl modified GPs/PVDF composites exhibited better dielectric properties than most carbon/polymer composites. POLYM. COMPOS., 37:327–333, 2016. © 2014 Society of Plastics Engineers     

Investigation on Electrocatalytic Activity and Stability of Pt/C Catalyst Prepared by Facile Solvothermal Synthesis for Direct Methanol Fuel Cell

Pt nanoparticles supported on Vulcan XC‐72 carbon black have been synthesized by a facile solvothermal method. The obtained Pt/C catalysts are characterized by X‐ray diffraction (XRD), energy dispersive X‐ray analysis (EDAX), and transmission electron microscopy (TEM) analysis to identify Pt mean size and Pt content. The results of electrochemical measurements demonstrate that the Pt/C catalyst prepared at the reaction temperature of 140 °C and the reaction time of 2 h shows the biggest initial electrochemical area with an initial electrochemically active specific surface area (ESA) of 70.6 m²g_Pt⁻¹, the highest electrocatalytic stability with an ESA loss of 48.7% after 1,000 CV cycles, and the best electrocatalytic activity and stability toward methanol oxidation reaction (MOR) with a specific activity of 0.6 mA cm⁻² and a retention rate (the ratio of the final current density to the maximum current density) after 3,600 s of 42.8%. Moreover, the electrochemical performance of homemade Pt/C catalyst is superior to that of commercial Pt/C catalyst, suggesting that the solvothermal synthesis is a promising method for preparing Pt based catalyst.