Electroactive Silk Fibroin Films for Electrochemically Enhanced Delivery of Drugs

Biomaterials capable of controlling the delivery of drugs have the potential to treat a variety of conditions. Herein, the preparation of electrically conductive silk fibroin film‐based drug delivery devices is described. Casting aqueous solutions of Bombyx mori silk fibroin, followed by drying and annealing to impart β‐sheets to the silk fibroin, assure that the materials are stable for further processing in water; and the silk fibroin films are rendered conductive by generating an interpenetrating network of a copolymer of pyrrole and 3‐amino‐4‐hydroxybenzenesulfonic acid in the silk fibroin matrix (characterized by a variety of techniques including circular dichroism, Fourier‐transform infrared spectroscopy, nuclear magnetic resonance, Raman spectroscopy, resistance measurements, scanning electron microscopy‐energy dispersive X‐ray spectroscopy, thermogravimetric analysis, X‐ray diffraction, and X‐ray photoelectron spectroscopy). Fibroblasts adhere on the surface of the biomaterials (viability assessed using an (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) assay and visualized using a confocal microscope), and a fluorescently labeled drug (Texas‐Red Gentamicin) can be loaded electrochemically and released (µg cm^?2 quantities) in response to the application of an electrical stimulus.     

Surface characterization of 8‐quinolinyl acrylate‐grafted poly(ethylene terephthalate) prepared by plasma glow discharge and it's antibacterial activity

Poly(ethylene terephthalate) (PET) film was exposed to oxygen plasma glow discharge to produce peroxides on its surface. These peroxides were then used as catalysts for the polymerization of 8‐quinolinyl acrylate (QA) to prepare the PET grafted with QA (PET‐Q). The surface‐modified PET was characterized by attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR) and X‐ray photoelectron spectroscopy (XPS). The introduction of QA to the PET surface was confirmed by observing the presence of nitrogen in the XPS survey scan and high‐resolution spectra. The amount of QA grafted on to the PET surface as measured by the gravimetric method was about 5.2 μg cm^?2. The antibacterial activity of the surface‐modified PET texture was investigated by using a shake‐flask and an inhibition zone test method. After 6 h of shaking, the PET grafted with QA showed the inhibition (91%) of the growth of the gram‐positive microorganism, S. aureus. Even after laundering ten times, an effectiveness of the inhibition was found. However, little inhibition was shown with the gram‐negative microorganism, K. pneumoniae. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 863–868, 2006     

Synthesis of BCN thin films by nitrogen ion beam assisted pulsed laser deposition from a B4C target

Using sintered B₄C as target material, ternary BCN thin films were synthesized on Si(100) substrates by means of reactive pulsed laser deposition assisted by nitrogen ion beam. The composition, bonding configuration and crystalline structure of the synthesized films were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. The prepared films contain several bonds including B–C, N–C, B–N with B–C–N atomic hybridization. The ablation of the B₄C target results in the deposition of a film with B:C ratio about 3:1, deficient in boron compared with the target material. Nitrogen provided by the ion beam is incorporated in the film and bonded to boron and carbon. Heating of the substrate enhances the incorporation of nitrogen and influences the bonding configuration and crystalline structure of the film as well.     

Grafting of polyacrylamide from poly(ethylene terephthalate) films

Poly(ethylene terephthalate) (PET) films were modified via the grafting of polyacrylamide (PAAM) onto the surface by surface‐initiated atom transfer radical polymerization and UV‐initiated grafting. The surface composition and morphology of the modified PET films were characterized by Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy (SEM). The results show that the surface of the PET film was grafted by PAAM, with its own surface morphology different from that of PET. The properties of the modified PET films were studied by contact‐angle, peeling force, penetrability, haze, and friction factor measurements. The results indicate that the peeling force and friction factor of the modified PET films were higher than those of the unmodified PET film. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polyimide nanohybrid films with electrochemically functionalized graphene

Graphite was functionalized electrochemically in a potassium fluoride solution and used to prepare polyimide (PI)/graphene nanohybrid films. The as‐made electrochemically fluorinated graphene (EFG) was used to prepare nanohybrid films with colorless PI, which was synthesized from 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride and bis(trifluoromethyl) benzidine by in situ polymerization. The surface functionalization of graphite was characterized by powder XRD, TEM with energy dispersive X‐ray spectroscopy elemental mapping, X‐ray photoelectron spectroscopy, Raman spectroscopy, and TGA. The microstructure of the films was characterized by Fourier transform IR spectroscopy, XRD and SEM. The film properties were measured using a universal testing machine, TGA, dynamic mechanical analysis, four‐point probe, UV–visible spectroscopy and water contact angle analysis. EFG improved the tensile strength and modulus of the nanohybrid films by 20% and 50%, respectively. The glass transition temperature and electrical conductivity of the nanohybrid films were 12 °C and nine orders of magnitude higher than those of the neat PI film, respectively. The nanohybrid film maintained 80% optical transmittance even after the addition of 0.1 wt% EFG. © 2019 Society of Chemical Industry     

Characterization of epoxy coatings on steel by reflection/absorption fourier transform infrared spectroscopy. I. Effects of film thickness and angle of incidence

Films of amine-cured epoxy coating of varying thicknesses from 100 Å to 2.5 μm on steel have been studied by reflection/absorption Fourier transform infrared spectroscopy (FTIR-RA). The shape and frequency of several strongly absorbed bands of epoxy have been examined as a function of film thickness and angle of incidence. Compared to transmission spectra, reflection/absorption spectra of epoxy coating on steel show band shifts and distortions of the bands at 1510, 1247, and 1040 cm^?1. These effects are more pronounced at increased thickness and at grazing angles. For thin films ( < 100 nm), RA spectral intensity increases with increasing angle of incidence. For thicker films, the relationship is quite complex. The relationship between film thickness and FTIR-RA spectral peak height of an amine-cured epoxy coating on steel has also been established.     

Polymer precursor to diamondlike carbon prepared by the polymerization of α,α,α‐trichlorotoluene and acetonitrile

A novel liquid/solid two‐phase reaction of α,α,α‐trichlorotoluene (PhCCl₃) and acetonitrile (AN) has been discovered that produces a carbon‐based polymer with diamondlike structure at the atomic level. The solid phase is potassium hydroxide particles, and the liquid phase is a tetrahydrofuran solution of PhCCl₃ and AN containing a certain amount of tetrabutylammonium bromide as a phase‐transfer catalyst. The structure of the carbon‐based polymer has been characterized by elemental analysis, Fourier transform infrared spectroscopy, and ¹H‐ and ¹³C‐NMR spectroscopy. The pyrolysis of the carbon‐based polymer at 800°C under a nitrogen atmosphere leads to the formation of a diamondlike carbonaceous material according to the results of X‐ray photoelectron spectroscopy and Raman spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 16–23, 2003     

Photocatalysis,microstructure, and surface characterization of TiO2‐loaded wooden‐activated carbon fibers

In this study, TiO₂‐loaded wooden‐activated carbon fibers (TiO₂/WACFs) were prepared by sol–gel method. TiO₂/WACFs were detected by scanning electron microscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy. The results showed that TiO₂ was deposited on almost each WCAF with a coating thickness. All the TiO₂ films on the surface of WACFs were composed of anatase with high photocatalytic property. The characteristic adsorption peaks of nano‐TiO₂ emerged at 1,402 and 471 cm⁻¹ on the infrared spectrum of TiO₂/WACFs. It was also found that Ti was in the binding state of Ti⁴⁺ (TiO₂) in the TiO₂/WACFs. As the calcination temperature increased, the content of elements Ti and Ti O bond of lattice oxygen on the surface of TiO₂/WACFs increased and then decreased, but the loaded nano‐TiO₂ did not affect the formation of graphite structure of WACFs. It is suggested that TiO₂/WACFs obtained at 450°C have the best photocatalytic property. POLYM. COMPOS., 36:62–68, 2015. © 2014 Society of Plastics Engineers     

Synthesis of N‐β‐aminoethyl‐γ‐aminopropyl polydimethyl‐co‐polydiphenylsiloxane and its film morphology and orientation

A fabric softener, N‐β‐aminoethyl‐γ‐aminopropyl polydimethyl‐co‐polydiphenylsiloxane (PASO), was synthesized by the polymerization of octamethyl cyclotetrasiloxane with an amino‐functional silane and dimethyldiphenylsilane. The chemical structure of the synthesized polysiloxane was characterized by Fourier transform infrared and ¹H‐NMR spectra. The morphology, composition, and hydrophobic properties of the PASO film were investigated by X‐ray photoelectron spectroscopy, atomic force microscopy, contact angle measurement, and other measurements. The experimental results indicate that on the silicon wafer surface, PASO formed a hydrophobic, nonhomogeneous structural film. In addition, the atomic force microscopy results show that the PASO film deposited on the silicon wafer seemed to be slightly rougher than the film of the control, the N‐β‐aminoethyl‐γ‐aminopropyl polydimethylsiloxane. As a result, an orientation model of PASO is proposed on the basis of the characterization of the PASO film properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of atomic oxygen and ultraviolet in low earth orbit on low surface energy polymer film

Effects of atomic oxygen (AO) and ultraviolet (UV) on a polymer film with surface energy of 8.0 mJ m⁻² derived from poly(1H,1H‐perfluorooctyl methylacrylate) were investigated by contact angle measurements, X‐ray photoelectron spectroscopy, and atomic force microscope. The film was exposed to AO with a flux of 6.73 × 10¹⁵ atoms cm⁻² s⁻¹ and UV with intensity of 15.8 mW cm⁻² at wavelength of 200–450 nm, respectively. It is found that AO and UV irradiation resulted in the reduction of film thickness, change of wettability, and increase of surface energy, and AO exhibited more serious effects than UV on the fluorinated polymer film. Reduced rate of thickness of the film was almost proportional to the AO exposure time. After exposed to AO and UV irradiation, the surface energy of the film increased to 17.3 mJ m⁻² and 11.0 mJ m⁻², respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of clay type on dispersion and barrier properties of hydrophobically modified poly(vinyl alcohol)–bentonite nanocomposites

The oxygen and water vapor permeability at high relative humidity was studied for composite films formed by incorporation of three different bentonites (MMT) into an ethylene‐modified, water‐soluble poly(vinyl alcohol), EPVOH. The oxygen permeability decreased linearly with an increased addition of hydrophilic MMTs. X‐ray diffraction and Fourier transform infrared spectroscopy suggested a homogeneous distribution in the thickness direction with disordered and probably exfoliated structures for hydrophilic MMTs. In contrast, organophilic modified clay showed an intercalated structure with the clay preferentially located at the lower film surface, a combination which was however efficient in reducing the water vapor‐ and oxygen permeabilities at low addition levels. Composite films of EPVOH and Na⁺‐exchanged MMT resulted in high resistance to dissolution in water, which was ascribed to strong interactions between the components resulting from matching polarities. Annealing the films at 120°C resulted in enhanced resistance to water dissolution and a further reduction in oxygen permeability. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42229.     

Solvothermal synthesis of various C3N4 films on FTO substrates and their photocatalytic and sensing applications

This paper reports solvothermal syntheses of pristine and KOH–NaCl-modified melon and melon–rGO composite films without post annealing and their applications in photocatalysis and Cu²⁺ sensing. Melon seed-layer coating enhanced film adhesion to fluorine-doped tin oxide substrates. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, and Raman spectroscopy were used to verify melon film structures. Assorted complex agents were studied to tailor film morphologies. (001)-Oriented nanorods were observed in KOH–NaCl-modified melon films. Constituent elements were determined based on their binding energies using X-ray photoelectron spectroscopy. Ultraviolet–visible and ultraviolet photoelectron spectroscopy were employed to confirm band gaps and valence band positions, respectively, of melon films. Associated energy-band diagrams were then constructed. The melon–rGO composite films exhibited superior photodegradation of methylene blue (degradation rate constant [k] ≅ 6.4 × 10⁻³/min) and rhodamine B (k ≅ 2.5 × 10⁻³/min) under visible-light irradiation. The performance was confirmed by nanorod structures, low photoluminescence emission, and high electrochemical surface areas. Furthermore, a reliable photoelectrochemical current density (~0.5 mA/cm²) at a 0.6-V bias was obtained for KOH–NaCl-modified melon and melon–rGO composite films. The KOH–NaCl-modified melon films demonstrated excellent selectivity between Cu²⁺ and Cr⁶⁺, indicating promising applications in Cu²⁺ sensing.     

Photoinitiated grafting of glycidyl methacrylate and methacrylic acid on ground tire rubber

Ground tire rubber (GTR) films and GTR particles were surface‐functionalized by glycidyl methacrylate and methacrylic acid through photoinitiated grafting. The grafting yield of GTR films was determined by Fourier transform infrared spectroscopy with attenuated total reflection (FTIR‐ATR). For the calibration of the FTIR‐ATR data, X‐ray photoelectron spectroscopy was used. The presence of epoxy and carboxyl groups on the GTR surface was demonstrated by contact‐angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1622–1630, 2003     

Some aspects of microstructural and dielectric properties of nanocrystalline CdS/poly(vinylidene fluoride) composite thin films

Free‐standing flexible composite films of nanocrystalline cadmium sulfide‐impregnated poly(vinylidene fluoride) (nano‐CdS/PVDF) were prepared using a sol–gel technique. The effect of CdS loading, in the PVDF host matrix, on the dielectric properties was studied. An increase in dielectric constant (more than 10 times) was observed in the films when poled under an electric field. The composite films were also characterized using microstructural, Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy measurements. © 2015 Society of Chemical Industry     

Hemocompatibility evaluation of polyurethane film with surface‐grafted poly(ethylene glycol) and carboxymethyl‐chitosan

To improve the hemocompatibility and biocompatibility of polyurethanes (PUs), PU surface was firstly modified by poly(ethylene glycol) PEG through acryloyl chloride and subsequently grafted on carboxymethyl‐chitosan (CMCS). Attenuated total reflection Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy analysis confirmed that carboxyl‐chitosan was grafted onto PUs surface. The surface properties of unmodified and modified PU films were determined and compared by water contact angle assessment. After PEG and CMCS grafting, the surface energy of the PU film was increased. Furthermore, the hemocompatibility of the modified PU films was systematically evaluated by bovine serum albumin (BSA) adsorption, the dynamic blood clotting test, the platelet adhesion test, and the hemolytic test. It appears that BSA adsorption and platelet adhesion were significantly curtailed for the modified PU films. Therefore, the obtained results showed the modified PU film has better hemocompatibility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Removal of N‐methylpyrrolidone hydrogen‐bonded to polyaniline free‐standing films by protonation–deprotonation cycles or thermal heating

Free‐standing films of polyaniline (PANI), in an emeraldine base state, prepared by evaporation of polymer solutions in N‐methylpyrrolidone (NMP) retain solvent even under dynamic vacuum drying as indicated by transmission Fourier transform infrared (FTIR) spectroscopy, where a band at 1670 cm^?1 is clearly observed. Upon protonation–deprotonation cycles in aqueous media the weight of the dry base film decreases indicating gradual loss of NMP. Transmission FTIR spectra shows also the washing out of NMP with a clear decrease in intensity of the hydrogen‐bonded >C?O stretching band (1670 cm^?1) of NMP. During this process the bands between 3500 and 3200 cm^?1, assigned to >N? H stretching in the PANI backbone, change intensity suggesting that intermolecular hydrogen‐bonded >N? H, with carbonyl oxygen of NMP, is replaced by free >N? H. This is clear evidence of specific interaction of NMP with the emeraldine base. A similar loss of NMP is observed during heating but evidence of polymer degradation is also present. A mechanism is proposed to account for the loss of hydrogen‐bonding ability upon protonation which requires delocalization of the radical cations in the protonated films. © 2001 Society of Chemical Industry     

Highly photoemissive polymer–transition metal complexes based on poly(2‐hydroxyethyl) methacrylate

The paper presents several new polymer complexes based on poly(2‐hydroxyethyl) methacrylate (P‐HEMA) and transition metals including Y³⁺, Eu³⁺, Tb³⁺ and Dy³⁺. Red‐, green‐, blue‐ and yellow‐emitting polymer complexes with remarkable photoluminescent (PL) properties, high degree of transparency and excellent processability both in bulk and in thin film were prepared and investigated. In the case of the prepared P‐HEMA–Eu³⁺ and P‐HEMA–Tb³⁺ polymer complexes, divinylbenzene was used as a crosslinker resulting a markedly enhanced PL emission, most probably due to the presence of the benzene rings which improve the efficiency of the energy transfer to the cation emissive centres. The prepared polymer complexes were structurally investigated through Fourier transform infrared and X‐ray photoelectron spectroscopies while atomic force microscopy was used to study the morphology of the prepared thin films. Steady‐state fluorescence spectroscopy and absolute PL quantum yield were used for the investigation of the luminescent properties. The impressive PL emission and the convenience of preparation in bulk or thin films could be important arguments for a wide area of applications ranging from photonic conversion materials in optoelectronic devices (light‐emitting diodes, flat‐panel displays) to full‐colour watermarks on special‐purpose papers or PL inks and coatings. © 2019 Society of Chemical Industry     

Matrix-assisted pulsed-laser evaporation of DOPA-modified poly(ethylene glycol) thin films

3,4-Dihydroxyphenyl-L-alanine-modified poly(ethylene glycol) (mPEG-DOPA₃) is a biologically-inspired material that exhibits unique adhesion properties. In this study, mPEG-DOPA₃ thin films were prepared using a novel laser process known as matrix-assisted pulsed-laser evaporation (MAPLE). The films were examined using Fourier transform infrared spectroscopy, atomic force microscopy, profilometry, antifouling studies and cell adhesion studies. The Fourier transform infrared spectroscopy data demonstrated that the main functional groups in the MAPLE-deposited mPEG-DOPA₃ films remained intact. Profilometry and atomic force microscopy studies confirmed that MAPLE provides excellent control over film morphology, as well as film thickness. High resolution patterns of mPEG-DOPA₃ thin films were obtained by masking. MAPLE-deposited mPEG-DOPA₃ thin films demonstrated an absence of cytotoxicity and acceptable antifouling properties against the marine bacterium Cytophaga lytica. MAPLE-deposited mPEG-DOPA₃ thin films potentially have numerous biomedical and marine applications.     

Synthesis,characterization and nonlinear optical properties of plasma‐prepared poly(4‐biphenylcarbonitrile) thin films

A novel conjugated polymer, poly(4‐biphenylcarbonitrile) (PBPCN), was prepared using a plasma polymerization technique. The effect of the discharge power on the chemical structure and surface compositions of PBPCN thin films was investigated using Fourier transform infrared, UV‐visible absorption and X‐ray photoelectron spectroscopies. A femtosecond time‐resolved optical Kerr effect technique was applied to investigate the third‐order nonlinearity of the obtained plasma PBPCN thin films. For the first time, a non‐resonant optical Kerr effect and ultrafast response for the PBPCN thin films were observed. Copyright © 2006 Society of Chemical Industry     

Some aspects of the properties of nylon‐6, 6/poly(ethylene naphthalate) blends

Blends of Nylon 66(Ny66) and polyethylene naphthalate (PEN) with 30, 50, 70 wt % Ny66, and one blend with 50% Ny66 and 3% compatibilizer, prepared by extrusion and injection molding, were investigated using ¹³C and ¹H nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). A new band in the FTIR spectra of blends, at 1324–1329 cm^?1 is interpreted as arising from partial reaction of Ny66 and PEN occurring during melt processing. However, NMR spectra show no evidence of interchange reaction between Ny66 and PEN. SEM indicates that the phase inversion point is close to equal proportions by weight of the two homopolymers. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1504–1514, 2001