Cold water fish gelatin films: Effects of cross-linking on thermal, mechanical, barrier, and biodegradation properties

Gelatin was extracted from Alaska pollock (Theragra chalcogramma) and Alaska pink salmon (Oncorhynchus gorbuscha) skins and cast into films. The fish gelatin films’ tensile, thermal, water vapor permeability, oxygen permeability, and biodegradation properties were compared to those of bovine and porcine gelatin films. In addition, fish gelatin films were cross-linked with glutaraldehyde. Pollock and salmon gelatin films had comparable tensile properties, but had lower tensile strength and percent elongation than mammalian gelatin films. The lower strength and elongation might have been due to lower structural gelatin levels present in fish gelatin films. The addition of cross-linkers had little effect on tensile properties and melting temperatures of fish gelatin films. Pollock gelatin films had the lowest water vapor and oxygen permeability values, whereas mammalian gelatin films had the highest permeability values. Cross-linking resulted in lower water vapor permeability for salmon gelatin films and higher oxygen permeability for pollock gelatin films. However, all fish gelatin films had better water vapor and oxygen barrier properties than mammalian gelatin films. Also, fish gelatin films degraded faster than mammalian gelatin films.     

类金刚石碳薄膜对碳膜导电性能的影响

以聚酰亚胺薄膜为原料,经炭化形成碳膜;进而在碳膜表面制备了类金刚石碳(DLC)薄膜,研究了制备条件对碳膜导电性能的影响.采用扫描电镜分析了薄膜的表面形貌和微观结构;采用X射线衍射仪分析了薄膜的晶体结构.结果表明,DLC薄膜的电阻率随着沉积时间的延长先减小后增加;当沉积时间达到3 h时,相应DLC薄膜的电阻率达到最小值5.66×10-5Ω.m.     

Characteristics of Sol-Gel SnO2 Films Treated by Ammonia

Tin dioxide thin films prepared by sol-gel dip-coating method with ammonia treatment have been studied. By using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy, detailed investigation on the structure and morphology of the films has shown the condensation of Sn-OH and the strengthening of gel network net through ammonia treatment, which leads to the improvement of the adhesion of the films. From the spectral transmission, angular distribution of reflectance and absorption spectrum, the optical properties of the ammonia treated films indicate that the ammonia treated films have a favorable optical performance, and the films are more suitable for acting as antireflective films than the heat-treated films. The ammonia treated films also exhibit higher conductivity compared with the non-treated films.     

Solid-phase microextraction based on polypyrrole films with different counter ions

Solid-phase microextraction (SPME) fiber coatings based on polypyrrole (PPY) films were prepared by electrochemical deposition of PPY films on platinum wires. To evaluate the effects of counter ions in PPY films on their performance in SPME, PPY films with different counter ions were prepared using different electrolytes during the polymerization processes. The results showed that these PPY films had different extraction properties to the compounds studied due to the different functional groups introduced into the films by the counter ions. Unlike the PPY films formed with small counter ions (such as perchlorate ion) that had anion exchange property, the PPY films having large counter ions such as poly(styrenesulfonate) (PSS) ion showed cation exchange property. Compared with the PPY films having small inorganic counter ions, the PPY films having large organic counter ions, such as dodecylsulphate (DS) ion, showed better extraction efficiency towards nonpolar compounds due to the increased hydrophobic interactions between the compounds and the films. In addition, PPY films formed with large aromatic counter ions had better mechanical stability compared with PPY films with small inorganic counter ions. These films could be applied for SPME of a range of analytes.     

不同干燥条件下壳聚糖膜表面的微观结构及微观力学性能

以自然风干(NW)、真空干燥(VD)及红外干燥(ID)三种干燥方式制备了壳聚糖膜.利用原子力显微镜(AFM)研究这三种壳聚糖膜的表面形貌及微观力学性能.实验结果表明VD和ID改善了膜材料的表面平整度,膜表面粗糙度分别为(5.47±1.34)和(2.79±0.93)nm,均显著低于NW膜((30.67±8.06)nm).干燥条件对壳聚糖膜的微观力学性能有较大影响:ID壳聚糖膜的粘附力((2595.0±68.5)pN)显著大于NW壳聚糖膜((982.6±149.3)pN)和VD壳聚糖膜((1817.9±279.2)pN);而ID壳聚糖膜的杨氏模量((158.8±15.2)MPa)则低于NW壳聚糖膜((204.3±22.7)MPa)和VD壳聚糖膜((195.8±14.6)MPa)的.     

聚合物的LB膜

简要介绍了聚合物LB(Langmuir -Blodgett)膜的制备装置和制备过程。同时对聚合物LB膜这一门学科最新的进展和应用前景做了较为详尽的介绍和论述。目前 ,随着对LB膜的研究深入 ,在对小分子LB膜、可聚合LB膜、聚合物LB膜的成膜研究中引入了将几种方法优点综合起来的新的成膜方法 ,并已成为研究热点     

溶胶-凝胶工艺制备发光薄膜研究进展

本文综述了通过深胶－凝胶工艺制备发光薄膜的基本过程、薄膜的表征方法、发光薄膜的当前发展及应用情况。依据组成特点,对溶胶－凝胶法制备的发光薄膜乾地了分类阐述,并预言了今后该法制备发光薄膜的发展趋势。     

Pre-irradiation induced grafting of styrene into crosslinked and non-crosslinked polytetrafluoroethylene films for polymer electrolyte fuel cell applications. I: Influence of styrene grafting conditions

Crosslinked and non-crosslinked polytetrafluoroethylene (PTFE) films [RX-PTFE and V-PTFE films, respectively], were irradiated in air at room temperature using γ-rays from a ⁶⁰Co source. The irradiated films were grafted with styrene in liquid phase. The grafting of styrene into PTFE films was proved by FT-IR spectroscopy. The influence of the reaction temperature and pre-irradiation doses on the resulted degree of grafting was discussed. The grafting speed and the degree of grafting were determined by the reaction temperature and pre-irradiation doses. The apparent activation energies were calculated as 39.7 kJ/mol for RX-PTFE films and 59.5 kJ/mol for V-PTFE films. The dependence index on absorbed doses at pre-irradiation for RX-PTFE films is 0.66, and for V-PTFE films it is 1.57. The geometric size changes of the grafted films were measured and discussed. Interestingly, the thickness of the grafted films was strongly influenced by the reaction temperature. The tensile strength and the elongation at break of the non-grafted and grafted RX-PTFE and V-PTFE films were measured. The grafted films then are sulfonated by chlorosulfonic acid for polymer electrolyte fuel cell (PEFC) applications and the highest IEC value gained is over 3. The analysis of the sulfonated films are now in progress.     

Preparation and characterization of microwave-treated carboxymethyl chitin and carboxymethyl chitosan films for potential use in wound care application

CM-chitin and CM-chitosan films were successfully crosslinked by microwave treatment. Crosslinking of the microwave-treated CM-chitin films involved mainly the carboxylate and the secondary alcohol groups, while crosslinking of microwave-treated CM-chitosan films involved the carboxylate and the amino groups. In addition, the crystallinity of CM-chitin increased with increasing microwave treatment time, whereas an increase in the crystallinity of the microwave-treated CM-chitosan films was not observed. At a similar percentage of weight loss, the crosslinking of either CM-chitin or CM-chitosan films by microwave treatment required much less stringent condition when compared with the crosslinking by autoclave treatment. Based on both direct and indirect cytotoxicity assays, the cytotoxicity of the microwave-treated CM-chitin films was negative, while that of the microwave-treated CM-chitosan films was positive. Human fibroblasts adhered on the surface of microwave-treated CM-chitosan films much better than on the surface of microwave-treated CM-chitin films.     

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.     

Effects of the polarizability and packing density of transparent oxide films on water vapor permeation

The tin oxide and silicon oxide films have been deposited on polycarbonate substrates as gas barrier films, using a thermal evaporation and ion beam assisted deposition process. The oxide films deposited by ion beam assisted deposition show a much lower water vapor transmission rate than those by thermal evaporation. The tin oxide films show a similar water vapor transmission rate to the silicon oxide films in thermal evaporation but a lower water vapor transmission rate in IBAD. These results are related to the fact that the permeation of water vapor with a large dipole moment is affected by the chemistry of oxides and the packing density of the oxide films. The permeation mechanism of water vapor through the oxide films is discussed in terms of the chemical interaction with water vapor and the microstructure of the oxide films. The chemical interaction of water vapor with oxide films has been investigated by the refractive index from ellipsometry and the OH group peak from X-ray photoelectron spectroscopy, and the microstructure of the composite oxide films was characterized using atomic force microscopy and a transmission electron microscope. The activation energy for water vapor permeation through the oxide films has also been measured in relation to the permeation mechanism of water vapor. The diffusivity of water vapor for the tin oxide films has been calculated from the time lag plot, and its implications are discussed.     

超疏水多孔阵列碳纳米管薄膜

碳纳米管由于具有特异的力学[1] 、光学[2 ] 、电学[3,4 ] 和磁学性质[5] ,使其在锂离子电池[6 ] 和平板展示器[7] 等方面呈现出广泛的应用前景 .Ebbesen等[8] 对无序碳纳米管材料的浸润性进行了详细研究 ,发现其很容易被水润湿 .然而 ,阵列碳纳米管膜的浸润性研究尚未见报道 .固体表面的浸润性主要由表面化学组分和几何结构两方面控制 .通常 ,加大表面粗糙度可以增强其浸润性 [9～ 16 ] .近来 ,超疏水表面 (即与水的接触角大于 1 5 0°的表面 )的研究显示了广泛的应用背景[13～ 16 ] .这种表面通常可由增加表面粗糙度和降低表面能来制备[1…     

Raman study of oriented ZnO thin films deposited by sol-gel method

ZnO films with preferred orientation along the (0 0 2) plane were successfully deposited by the sol-gel method using Zn(CH3COO)2.2H2O as starting material and inorganic precursor. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of ethanol and monoethanolamine. Thin films are obtained by spin-coating on glass substrates. ZnO films were obtained by preheating the spin-coated films at 300 degrees C for 10 min after each coating and postheating upto 550 degrees C for 2h. The as-deposited films are transformed into mono-oriented ZnO upon thermal treatment. The films consist of spongy particles aggregates with an uniform size and homogenous surface. The films aim to be used in optoelectronic devices. Raman spectroscopy from ZnO films and deposit solutions has been investigated. New Raman results of the deposit solution suggest that Zn-O bond forms first in solution and that these entities play the role of germs initiating the crystallization mechanisms during films annealing. Raman spectra of the annealed films show the presence of a compressive stress within the film structure.     

Dielectric Characteristics of Sol-Gel-Derived BST/BSLaT/BST Multilayer

BST/BSLaT/BST multiplayer (ML) films were prepared by sol-gel method on the Pt/Ti/SiO₂/Si substrate. X-ray diffraction analysis and atomic force microscopy showed that dopant La causes decreased grain size of BST thin films obviously, and ML films were similar to BST films in size. The dielectric constant versus temperature curve of ML films becomes sharper comparing with that of BST films near the phase transition point, which indicated that the pyroelectric coefficient is propitious to be enhanced. The ML films also improve the leakage current characteristics of BST thin films and the linear relationship of the log J versus E^1/2 curves shows in a good agreement with the Schottky thermionic emission model. This work clearly reveals the highly promising potential of BST/BSLaT/BST multiplayer films compared with BST films for application in uncooled infrared focal plane arrays system.     

Layer-by-layer assembly for rapid fabrication of thick polymeric films

In the past two decades, layer-by-layer (LbL) assembly has been proven to be a convenient and versatile method to fabricate functional films. However, using traditional dipping LbL assembly to fabricate micrometer-thick films is time consuming. Compared with ultrathin films, micrometer-thick films prepared by LbL assembly possess enhanced mechanical stability, and allow deposition of a significantly increased amount of materials and the integration of multiple functions. These merits of thick films produced by LbL assembly can result in new functions and allow the functions of ultrathin films fabricated by LbL assembly to be optimized. In this tutorial review, the methods for rapid fabrication of thick polymeric films involving LbL assembly are reviewed. The functions of such films that are relevant to their micrometer thickness are discussed.     

Preparation and application of alumina- and titania- nanocrystals-dispersed thin films via sol-gel process with hot water treatment

A process to prepare nanocrystals-dispersed thin films at low temperatures using a hot water treatment of the gel films, and application of these nanocomposite thin films were demonstrated. When amorphous Al₂O₃ gel films were immersed in a hot water, we found that boehmite nanocrystals were formed on the surface of the films. In the hot water treatment of Al₂O₃-ZnO amorphous films, Zn-Al layered double hydroxide (LDH) was found to be formed on the films. When the SiO₂-TiO₂ gel films containing poly(ethylene glycol) were treated in a hot water, anatase nanocrystals were formed on the surface and inside of the films, and for the gel films without an organic polymer, the anatase nanocrystals were formed only on the surface of the films. In the hot water treatment of SiO₂-TiO₂ gel films under a vibration, titania nanosheets were found to be precipitated, instead of anatase nanocrysltals. Since formation of nanocrystals on the substrates using a hot water treatment is very mild conditions as the precipitation of crystals, we believe this process will open new application fields of nanocystals-dispersed thin films.     

Resin impregnation of cellulose nanofibril films facilitated by water swelling

Flexible composite films were produced by impregnating aqueous phenol formaldehyde (PF) resin into water-swollen cellulose nanofibril (CNF) films. CNF films were prepared using a pressurized filtration method in combination with freeze drying. The freeze-dried films were swollen with water then impregnated with PF resin by soaking in aqueous resin solutions of varying concentrations. Small amounts of PF slightly enhanced the tensile properties of CNF films. The formulation with the best mechanical properties was CNF/PF films with 8 wt % resin exhibiting tensile stress and toughness of 248 MPa and 26 MJ/m³, respectively. Resin concentrations higher than about 8 % resulted in composites with decreased tensile properties as compared to neat CNF films. The wet strength of the composite films was significantly higher than that of the neat CNF films. The resulting composites showed greater resistance to moisture absorption accompanied by reduced thickness swelling when soaked in water as compared to neat CNF films. The composites also showed decreased oxygen permeability at low humidity compared to neat films, but the composites did not show improved barrier properties at high humidity.     

Peculiarities of Electrochemical Bismuth Film Formation in the Presence of Bromide and Heavy Metal Ions

Bi films were deposited on glassy carbon electrode from solutions with and without KBr. The morphology of both types of the films was characterized by scanning electron microscopy (SEM), and their electrochemical behavior was studied by square wave (SWV) and cyclic voltammetry (CV). Bi films were also co‐deposited with common analyte‐heavy‐metals in the presence of KBr and these films also were characterized by SEM, SWV and CV in order to understand the formation of the mixed metal films. All films studied had a different morphology. Bromide addition made the Bi films more compact and uniform, whereas Pb catalyzed Bi film deposition.     

Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.     

Layer-by-layer growth of thin amorphous solid water films on Pt(111) and Pd(111)

The growth of amorphous solid water (ASW) films on Pt(111) is investigated using rare gas (e.g., Kr) physisorption. Temperature programmed desorption of Kr is sensitive to the structure of thin water films and can be used to assess the growth modes of these films. At all temperatures that are experimentally accessible (20-155 K), the first layer of water wets Pt(111). Over a wide temperature range (20-120 K), ASW films wet the substrate and grow approximately layer by layer for at least the first three layers. In contrast to the ASW films, crystalline ice films do not wet the water monolayer on Pt(111). Virtually identical results were obtained for ASW films on epitaxial Pd(111) films grown on Pt(111). The desorption rates of thin ASW and crystalline ice films suggest that the relative free energies of the films are responsible for the different growth modes. However, at low temperatures, surface relaxation or "transient mobility" is primarily responsible for the relative smoothness of the films. A simple model of the surface relaxation semiquantitatively accounts for the observations.