Biocompatible agar/xanthan gum composite films: Thermal,mechanical, UV,and water barrier properties

Binary composite films were prepared from agar (A) and xanthan gum (X) with different weight percentages. The composite films were transparent, lightweight, eco‐friendly, and biodegradable. The structure and morphology of the prepared agar and AX composite films were confirmed by Fourier transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRD), and scanning electron microscopy (SEM) technique. The glass transition temperature (T_g) and melting temperature (T_m) of the AX composite films was slightly improved, when compared with the neat agar. Thermogravimetric analysis (TGA) analysis showed a considerable increment in the char yield and an improved thermal stability. The tensile strength was in the range of 25 to 40 MPa, and elongation at break was in the range of 28.9 to 39.4%. Though, the water vapor permeability (WVP) value reduced in the composite films the difference was not significant. From the mechanical studies, we can deduce that agar and xanthan gum are compatible and miscible with one another leading to prospects of their composite films being considered for different biomedical and packaging applications.     

Highly flexible, transparent cellulose composite films used in UV imprint lithography

Highly flexible, optically transparent epoxy resin/cellulose composites were prepared by using the solution impregnation method firstly and then thermal cured. The composite contained 60 wt% resin was still mechanically stable and flexible, and it integrated the merits of cellulose and resin, but the highly hydrophilic behavior of cellulose has been reduced. Contact angle measurements with water demonstrated that the composite films had obvious hydrophobic properties, and a decrease in the water uptake and the permeability towards water vapor gas was also observed. The transmittance of the composite films at 550 nm was about 85–88 %. The thermal and mechanical properties of the composite films were improved. Moreover, the composite films could be used in UV imprint lithography for circuit, and the definition could be compared with that of widely used glass plate.     

Polyaniline/poly(vinyl alcohol) (PAN/PVA) composite films: the synergy of film structural stiffening, redox amplification, and mobile species compositional dynamics

In this work, we report an unexpected but significant improvement of the redox behavior of conducting polyaniline (PAN) films by trapping intrinsically nonconducting poly(vinyl alcohol) (PVA) in the matrix of the polymer acting as stiffening and/or cross-linking agents. Film structural stiffening of PAN/PVA inclusion was studied in relation to film compositional dynamics. PAN and PAN/PVA composite films were potentiodynamically deposited using high-frequency electrochemical quartz crystal microbalance under electrochemical potentiodynamic control. From the simultaneously obtained measurements of nanogravimetric and cyclic voltammetric data, it has been found that the presence of PVA in the deposition solution increased the rate of PAN film growth as a function of PVA concentration. Characterization of the resultant composite films in monomer-free acidic electrolyte solutions showed significantly enhanced redox behavior of PAN/PVA composite films (with different PVA contents) compared to pure PAN by a factor of ～2–4. For the study of structure–composition relationships of composite polymer films, fluxes of instantaneous mobile species dynamics (ion/solvent) as a function of film redox conversion and potential cycling were correlated with film structural stiffening and the observed unusual redox enhancement of PAN/PVA composite films. Using various experimental timescales, we were able to resolve bound (associated with ion transfer) and free solvent compositional dynamics (associated with thermodynamic activity balance).     

Fabrication, Characterization, and Surface-Enhanced Raman Activity Study of Silver Coated Gold Nanoparticulate Films

This paper reports a study on the preparation of Ag-clad Au colloidal monolayer films by a combination of colloid self-assembly and liquid phase microwave high-pressure technique. Firstly, monodisperse Au nanoparticles prepared by microwave heating method were assembled onto a quartz slide. Then, these Au colloidal particles on the quartz surface acted as seeds for growing the Ag-clad Au composite particulate films. The obtained particulate films were characterized by UV-Vis spectra and atomic force microscopy. It was found that the thickness of the shell and thus the size of particles in the composite colloidal films could be controlled by deposition of Ag on the preformed Au colloidal particle film in the microwave reaction system, and such films significantly increased the surface-enhanced Raman scattering enhancement （SERS） ability compared with Au colloidal particle films. Their strong enhancement ability may mainly stem from relatively large particle consisting of Ag cladding as well as effective coupling among particles in the Ag-clad Au particle ftlms.     

Vacuum evaporation-deposited polyterafluoroethylene films: Growth mechanism,properties, and applications

The method of vacuum evaporation deposition of polyterafluoroethylene films under additional vapor activation with an electron cloud and low temperature plasma was described. The film composition, structure, and properties can be controlled by deposition conditions. Co-evaporation with metals and dyes allowed deposition of various composite films. Gold-filled films were modified with thiol for gas sensor applications.     

Dye-polyoxometalate composite films: self-assembly, thermal and photochemical properties

A series of dye-polyoxometalate composite films were prepared by alternately depositing cationic dye molecules and anionic polyoxometalates such as Keggin-type [BW(12)O(40)](5-) and the sandwich complex [Co(4)(H(2)O)(2)(PW(9)O(34))(2)](10-)via layer-by-layer (LbL) self-assembly method. These cationic dye molecules (MB, AA, TH, BB3, BCB and NB) are heterocyclic planar and rigid phenothiazine and phenoxazine dye molecules with different substituting groups in the side chains. The self-assembly of the films was studied by UV-vis and IR spectra. The results show that the substituting groups of dye molecules such as NH(2) and CH(2)CH(3) have influence on the self-assembly properties. The continuous and regular growth of the films was also dependent upon hydrogen bonding (NHO) formed between the amino groups of dye molecules and oxygen atoms of POMs as well as electrostatic interactions. The investigation of thermal and photochemical treatments of the composite films is also presented. The thermal stability experiments indicate that the composite films of TH with two NH(2) substitute groups and NB with more pi-conjugated system exhibit high thermal stability, whereas the sunlight irradiation results indicate that the composite films of TH have good photochemical stability.     

Composite cellulose-polyacrylonitrile films prepared from solutions in a mixed solvent, 1-butyl-3-methylimidazolium chloride-dimethylformamide

Composite films were prepared from solutions of cellulose-polyacrylonitrile blends in a mixed solvent, 1-butyl-3-methylimidazolium chloride-dimethylformamide. The rheological properties of the solutions were studied. The structural organization and heat resistance of the composite films were examined by X-ray diffraction and thermal gravimetric analysis. Introduction of cellulose into the polyacrylonitrile matrix decreases the temperature of polyacrylonitrile cyclization onset and enhances the heat resistance of the composite films.     

Thermal,mechanical, and topographical evaluation of nonstoichiometric α-cyclodextrin/poly(ε-caprolactone) pseudorotaxane nucleated poly(ε-caprolactone) composite films

Three pseudorotaxanes (PpR) comprised of poly (ε-caprolactone) (PCL) and α-cyclodextrin (α-CD) with varying stoichiometric ratios were synthesized and characterized. Wide-angle X-ray diffraction (WAXD) and thermogravimetric (TGA) analyses provided conclusive evidence for complexation between the guest PCL and host α-CD. The as-synthesized and characterized PpRs were used at 10 and 20% concentrations as nucleants to promote the bulk PCL crystallization in composite films. Both WAXD and TGA provided evidence for intact PpR structures in the composite films. Isothermal differential scanning calorimetric (I-DSC) analyses, performed at various crystallization temperatures demonstrated significant differences in the crystallization patterns among the composite films. In addition, I-DSC analyses showed higher Avrami constant values (n) in the PpR-nucleated composite PCL films (n ~ 3), indicating 3-dimensional crystal growth. In the case of neat PCL films, however, lower n values indicated crystal growth in 1-dimensions or 2-dimensions. Moreover, atomic force microscopic analyses showed large crests and pits in PpR-nucleated PCL composites, with irregular morphologies leading to higher surface roughness. To the contrary, the crests and pits were much smaller in the neat PCL films, resulting in lower surface roughness values. Finally, mechanical testing revealed higher tensile strength for PpR-nucleated PCL composites films, demonstrating larger load bearing capabilities. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 1529–1537     

PREPARATION, CHARACTERIZATION AND ELECTROCHEMICAL PROPERTIES OF POLYPYRROLE-POLYSTYRENE SULFONIC ACID COMPOSITE FILM

Polypyrrole-polystyrene sulfonic acid (PPy-PSSA) composite films have been electrosynthesized in an aqueous solution of PSSA. The electro-active films exhibit cation exchange during the redox process. Infrared, Raman and energy-dispersive spectroscopic results demonstrated that the polyanion of PSS^- is co-deposited into the PPy matrix and couldn‘t be stripped from the film extensively by dedoping. The doping level together with dipolaron content of the PPy-PSSA composite film increases during electrochemical polymerization process. SEM images revealed that the composite film has smooth and compact morphology and AFM pictures suggested that PPy chains are possibly grown perpendicular to the electrode surface. TGA tests indicated that the composite films has much better thermal stability than that of pure PPy.Furthermore, electrochemical studies showed that the relaxation process at certain holding potential has great effect on the shape of the cyclic voltammetric curves of PPy-PSSA composite film. The composite film exhibits cation and anion exchange during the redox process after undergoing the relaxation step. It is more difficult for divalent anion to enter the polymer matrix than a univalent ion, and a large cation such as (CH3CH2CH2CH2)4N^ cannot be involved in the ion exchange process.     

纳米TiO_2改性蚕丝丝素蛋白膜的研究

用溶胶凝胶法制备纳米TiO2改性再生蚕丝丝素蛋白膜.该丝素膜机械强度提高,在水中溶失率下降.UV、AFM、SEM测试的结果表明,丝素中纳米TiO2粒径约为80 nm,纳米粒子在丝素膜中分布均匀;XRD、FTIR测试结果表明,纳米TiO2的加入,可使改性丝素膜的结晶结构从SilkⅠ向SilkⅡ转化,其结晶度也随之提高;TGA测试表明改性丝素膜的热转变温度比纯丝素膜有所改变.     

纳米Au-TiO2复合薄膜的溶胶-凝胶法制备、表征和性能

用溶胶-凝胶法制备了纳米Au-TiO₂复合薄膜.X射线衍射、X射线光电子能谱、原子力显微镜、紫外-可见光谱及摩擦磨损实验研究表明,复合薄膜均匀致密,Au以纳米晶粒形式均匀、不连续分散镶嵌于TiO₂基体中,纳米Au粒径为14～25nm;复合薄膜在可见光区有较强的吸收,吸收峰位置和强度与烧结温度和金的添加量有关;复合薄膜具有良好的抗磨减摩性能,在1N负荷下,摩尔分数为5%的Au-TiO₂薄膜的摩擦系数仅为0.09～0.10,耐磨寿命多于2000滑动周次.     

Preparation,characterization, and thermal studies of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> and CuO dispersed polycarbonate nanocomposites

Polycarbonate with γ-Fe₂O₃ and CuO dispersions were carried out by solvent casting method to make polycarbonate-γ-Fe₂O₃ and polycarbonate-CuO composite films. These films were characterized for the molecular structure through FTIR spectroscopy and crystallinity by X-ray diffraction (XRD) measurements. The morphology of polycarbonate-γ-Fe₂O₃ was found to be different from that of polycarbonate-CuO composite films based on the scanning electron micrograph (SEM) images. The thermal traces of composites are different from that of pure polycarbonate which indicating the catalytic decomposition when compared with virgin polymer which is oxidative decomposition. An understanding of the structure, morphology, and thermal behaviour of the composite films are envisaged in the present study.     

Sandwich-like QDs/MOFs films for selective sensing and multicolor emitting

A novel type sandwich-like composite films composed of ZIF-8 and CdTe QDs were successfully constructed through facile layer-by-layer assembly strategy and their potential applications were also explored. Based on the limitation effects of the aperture of ZIF-8, CdTe QDs/ZIF-8 fluorescent composite films exhibit obvious selective optical response toward hydrogen peroxide and folic acid. Furthermore, tunable colorful light emission composite films in the red-green region are obtained through incorporating two different sized QDs and ZIF-8 films into one composite films.     

SiW12、PbS对提高TiO2纳米管光电转换效率的协同效应研究

复合薄膜可以改善TiO2纳米管在光电转换时电子-空穴易复合和吸收光谱范围窄的缺陷。用电沉积法将多酸H4SiW12O40（SiW12）沉积在TiO2纳米管表面形成SiW12/TiO2纳米管复合薄膜,再用连续离子层吸附反应法（SILAR）将PbS吸附到SiW12 /TiO2纳米管复合薄膜表面,形成PbS/ SiW12/TiO2纳米管复合薄膜,所得薄膜的光电转换效率相较于TiO2纳米管提高了57倍。X射线衍射（XRD）和扫描电子显微镜（SEM）表征结果表明,用电沉积法和连续离子层吸附反应法实现了PbS/SiW12/TiO2纳米管复合薄膜的制备;紫外可见（UV-vis）吸收光谱测试表明,复合薄膜的光吸收带边扩展到了可见光区域,电化学阻抗测试（EIS）表明,复合薄膜具有更高的电子转移速率;荧光光谱（PL）测试表明,复合薄膜拥有更小的电子-空穴复合率。以上结果说明,SiW12、PbS与TiO2纳米管复合,很好地抑制了TiO2纳米管电子-空穴的复合,并拓宽了吸收光谱范围,能显著地提高TiO2纳米管的光电性能。本文探索了一种有效提高TiO2纳米管光电转换效率的方法,对TiO2纳米管复合薄膜的制备具有一定的参考意义。     

THE PREPARATION AND STUDY ON THE NANO-TiO2/SILK FIBROIN COMPOSITE FILMS BY THE SOL-GEL METHOD

Based on the sol-gel technique using butyl titanate as oxide precursor, the regenerated SF (silk fibroin)/nano-TiO2 composite films were synthesized. Different amounts of butyl titanate to SF were used to verify this effect on the characteristics of the formed materials. Samples were characterized by thermogravimetric analysis, X-ray diffractometry, UV, AFM and FT-IR spectroscopy.The experimental results reveal that, compared to the pure silk fibroin films, the mechanical strength of these regenerated SF/nano-TiO2 composite films were increased and the dissolubility in water of SF/nano-TiO2 composite films in aqueous solution were decreased. The diameter of nano-TiO2 particle films was about 80nm through UV and AFM. The nano-TiO2 particles were well dispersed in the regenerated silk fibroin. It was found that the crystal structures of the composite films were transited from typical Silk Ⅰ to typical Silk Ⅱ by the XRD and FTIR. Furthermore, the crystallinity of the composite films was obviously improved. Through the TGA, it was demonstrated that the heat transition temperature of composite films was also enhanced.     

Rodlike/flexible polyimide composite films prepared from soluble poly(amic diethyl ester) precursors: Miscibility,structure, and properties

Homogeneous precursor/precursor solutions with various compositions were obtained with appreciably high solid contents in N-methyl-2-pyrrolidone from soluble poly(amic diethyl ester) precursors of rodlike poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) and flexible poly(4,4′-oxydiphenylene biphenyltetracarboximide) (BPDA-ODA), which are hydrolytically more stable as well as more soluble than the corresponding poly(amic acid)s being equilibrated with the constituent monomers. Both optical microscopic and light scattering measurements showed that the dried precursor blend films and resultant polyimide composite films were optically transparent, regardless of compositions and process conditions. The composite films showed a single T_g behavior. However, for the composite of 30 wt % BPDA-PDA dispersed in the matrix of 70 wt % BPDA-ODA, a smectic crystalline-like aggregation of the BPDA-PDA component was detected on wide-angle x-ray diffraction patterns, indicative of microscopic phase separation between the two components. This phase separation was not detected on the optical microscopy, light scattering, and dynamic mechanical thermal analysis because of their resolution limits: Optical microscopy has a resolution of submicrometers, whereas dynamic mechanical thermal analysis and light scattering have a resolution of ca. 50 Å. Therefore, it is speculated that in the composite films BPDA-PDA and BPDA-ODA polyimide molecules have demixed on the scale of a few nanometers. The mean long periodicity, which was estimated from the small-angle x-ray scattering pattern, varied from 134 to 170 Å as the content of BPDA-ODA component increased. In addition, mechanical properties of the composite films were characterized. ©1995 John Wiley & Sons, Inc.     

Ternary composite films of natural rubber,cellulose microfiber,and carboxymethyl cellulose for excellent mechanical properties,biodegradability and chemical resistance

Cellulose - Fast and facile preparation of composite films containing natural rubber and Eucalyptus cellulose microfiber was achieved by the addition of carboxyl methyl cellulose to yield advantage...     

Synthesis and characterization of a new conducting polymer composite

Organic conductive composite films have been synthesized by electropolymerization of pyrrole in the presence of chitosan and p-toluene sulfonic acid sodium salt. The obtained conductive polymer composite films have been characterized by Fourier Transform Infrared spectroscopy, dynamic mechanical analysis, scanning electron microscopy, X-ray diffraction and conductivity measurements. The prepared polymer composite films had the amorphous structure and exhibited the enhanced conductivity and mechanical properties due to the presence of chitosan in the composite films.     

Layer-by-layer assembly of cationic guar gum,cellulose nanocrystals and hydroxypropyl methylcellulose based multilayered composite films

Eco-friendly sustainable materials provide an appealing template to replace contemporary synthetic-nonrenewable resource-based materials while maintaining the acceptable material properties to meet the performance requirements. Here, a layer-by-layer (LBL) self-assembly technique was used for fabricating multilayer composite films using all bio-based polymers/polysaccharides, i.e. cationic guar gum (CGg), carboxylated cellulose nanocrystals (cCNCs) and hydroxypropyl methylcellulose (HPMC). A five layered composite film was fabricated by depositing polymeric layers as follows: CGg→cCNCs→HPMC→cCNCs→CGg. The structural analysis of (CGg/cCNCs/HPMC)_5 L multilayered composite films indicated the existence of electrostatic interaction as well as H-bonding between polymeric layers that resulted in homogenous, dense and compact film surface with improved smoothness and strength properties. As compared to pure CGg film, the (CGg/cCNCs/HPMC)_5 L multilayered composite films showed improved tensile strength (84.8?% increment) and modulus (29.19?% improvement). Importantly, the deposition of HPMC layer contributed in achieving multilayer composite films with more flexible behavior (46.55?% improvement in elongation at break). Furthermore, owing to the high transparency (89.5?% transmittance), appreciable gas and oil barrier performance and resistance to various solvents (e.g. acetone, THF and DMAc), these multilayer films are promising candidates for various applications including renewable/sustainable packaging materials.

     

Microstructure,magnetoelectric properties and leakage mechanisms of La0.7Ca0.3MnO3/Bi3.15Nd0.85TiO3 composite thin films

A series of high quality Bi_3.15Nd_0.85TiO₃ (BNT) ferroelectric thin films and La_0.7Ca_0.3MnO₃/Bi_3.15Nd_0.85TiO₃ (LCMO/BNT) multiferroic composite thin films were deposited on Pt(111)/Ti/SiO₂/Si(100) substrates by chemical solution deposition (CSD) method. The microstructure, surface morphology and leakage mechanisms of BNT and LCMO/BNT composite films were revealed by X-ray diffraction, scanning electron microscopy and semiconductor device analyzer, respectively. Ferroelectric behavior along with a remnant polarization (2P_r) of 20 μC/cm², saturated magnetization around 56 emu/cm³ and magnetoelectric effect (ME) voltage coefficient α_ME of 33 mV/cm Oe at 1 kHz for LCMO/BNT composite films were obtained at room temperature, indicating that the coupling effects of electric and magnetic field exist in the fabricated LCMO/BNT multiferroic composite thin films. And our observations provide an effective way to manipulate the conduction behavior and push forward understanding the leakage mechanism in LCMO/BNT composite films.