Preparation and properties of thermo-sensitive organic/inorganic hybrid microgels

By utilizing the hydrolysis and condensation of the methoxysilyl groups, thermo-sensitive organic/inorganic hybrid poly[ N-isopropylacrylamide- co-3-(trimethoxysilyl)propylmethacrylate] [P(NIPAm- co-TMSPMA)] microgels were successfully prepared via two different methods without addition of any surfactant. First, the microgels were obtained by a two-step method; that is, the linear copolymer P(NIPAm- co-TMSPMA) was first synthesized by free radical copolymerization, and the aqueous solution of the copolymer was then heated above its low critical solution temperature (LCST) to give colloid particles, which were subsequently cross-linked via the hydrolysis and condensation of the methoxysilyl groups to form the microgels. Second, the microgels were also prepared via conventional surfactant-free emulsion polymerization (SFEP) of the monomers NIPAm and TMSPMA. TMSPMA can act as the cross-linkable monomer. No surfactant was involved in the preparation of the hybrid microgels. The obtained microgels were rather spherical and exhibited reversible thermo-sensitive behavior. The size, morphology, swellability, and phase transition behavior of the microgels were dependent on the initial copolymer or monomer concentration, preparation temperature, and the content of TMSPMA. The size of microgels obtained by SFEP was found to be more uniform than that by the two-step method. The hybrid microgels obtained by these two methods had more homogeneous microstructures than those prepared via conventional emulsion polymerization with chemical cross-linker N, N'-methylene-bisacrylamide.     

Layer‐by‐Layer Assembly for Surface Tethering of Thin‐Hydrogel Films: Design Strategies and Applications

Manipulation and engineering of the surfaces has a key role in improving the materials properties. Anchoring of thin hydrogels on the materials surface is one of the recently developed methods to achieve surfaces with high potential applications. Layer‐by‐layer (LBL) has been used widely as a strong strategy for immobilization of thin hydrogel films on the surface of various organic/inorganic substrates. Electrostatic LBL and covalent LBL are two main strategies used in this regard. In electrostatic LBL, negatively and positively hydrophilic polymers are sequentially assembled to create a multilayer hydrogel which subsequent covalent crosslinking of multilayers improved the stability of the inserted layers. On the other hand, covalent LBL requires hydrophilic polymers bearing reactive telechelic groups. These reactive polymers are prepared by various polymerization techniques or by post‐functionalization of biopolymers. The principles of hydrogel anchoring have described along with representative examples. Besides, the potential applications of the modified surfaces in specific cases have been addressed and overviewed.     

高折射率有机/无机纳米杂化透明膜层材料的制备与性质研究

采用溶胶-凝胶法,将钛酸酯和硅烷偶联剂(KH-560)进行共水解,经涂膜、固化,制备了一系列含有无机二氧化钛纳米相的无机/有机杂化膜层材料,通过不同方法对杂化膜层的微结构、光学、机械和热性质进行了表征.结果表明,所得到的有机/无机纳米复合膜层,在可见光范围内的透过率均在90%以上,同时具有较好的耐热性和较高的折射率(nd=1.47~1.73),并且膜层与基材的附着性好,铅笔硬度达到4~5H.     

Preparation and characterization of poly(phthalazinone ether ketone)/SiO<Subscript>2</Subscript> hybrid composite thin films with low friction coefficient

Organic–inorganic poly(phthalazinone ether ketone) (PPEK)/SiO₂ hybrid composite thin films were prepared by the dip-coating method on pre-cleaned glass substrates. The covalent bonds between organic and inorganic phases were introduced by an in-situ O-acylation reaction of isocyanatopropyltriethoxysilane (ICPTES) with the borohydride-reduced PPEK forming a polymer bearing triethoxysilyl groups. Theses groups were subsequently hydrolyzed with tetraethoxysilane (TEOS) and allowed to form a network via a sol–gel process. The polymer hybrid composite exhibited good thermal stability and a higher glass transition temperature as compared with the pure resin. Atomic force microscope, water contact angle measurement and scanning electron microscope were used to characterize the polymer hybrid thin films. The tribological experiment showed that the films have very low friction coefficient (about 0.1) and good anti-wear properties, without failure even after sliding for 18,000 s under modest loads. The improved tribological properties of the modified substrate were attributed to good adherence of PPEK/SiO₂ hybrid films on the substrate and synergy of both PPEK matrix and silica particles.     

Reaction kinetics and network characterization of UV-curing polyester acrylate inorganic/organic hybrids

Polyester acrylate inorganic/organic hybrids were prepared using a sol-gel precursor, coupling agent, and reactive diluent. The hybrids were cured via a UV-free radical initiator. Design of experiments (DOE) was utilized to investigate reaction kinetics and complex variable interactions. The effects of the silicate groups on the free radical photo-curing reaction kinetics were investigated utilizing a time-resolved Fourier transform infrared (FT-IR) spectroscopy and a differential scanning calorimeter equipped with a photocalorimetric accessory (photo-DSC). Microgel and inorganic network formation during the UV-initiated free radical crosslinking reactions was suggested to describe the complex gel-point behavior. It was proposed that the formation of the inorganic silicate groups retarded the organic crosslinking reactions. The UV-cured inorganic/organic hybrid films exhibited more homogeneous film morphology compared to the organic counterparts. In the hybrid films, a core-shell like inorganic/organic particle morphology was observed. The UV-crosslinked organic phase forms the core, whereas, the inorganic silicate forms the surrounding shell.     

Highly disordered polymer field effect transistors: N-alkyl dithieno[3,2-b:2',3'-d]pyrrole-based copolymers with surprisingly high charge carrier mobilities

A series of novel electroactive and photoactive conjugated copolymers based on N-alkyl dithieno[3,2-b:2',3'-d]pyrroles (DTP) and thiophene (TH) units (DTP-co-THs) were synthesized using a Stille coupling reaction and exhibited molecular weights of 1.6 x 10(4) to 5.0 x 10(4) g/mol. The incorporation of soluble substituted thiophenes and planar DTP units resulted in low band gap, highly conductive polymers. DTP-co-THs exhibited excellent solubility in common organic solvents and formed high-quality films. Optical characterization revealed that the band gaps of DTP-co-THs were between 1.74 and 2.00 eV, lower than regioregular poly(3-alkylthiophenes). Electrochemical characterization showed that the HOMO energy levels of DTP-co-THs are between -4.68 and -4.96 eV. When doped, DTP-co-THs exhibited high conductivities up to 230 S/cm with excellent stability. The different thiophene substituent patterns' effect on the polymers' optical and electronic properties was then examined by density functional theory computations. The microstructure and surface morphologies of poly(2,6-(4-dodecyl-4H-bisthieno[3,2-b:2',3'-d]pyrrole)-random-2,5-(3-dodecylthiophene)) (P4) and poly(2-(4,4'-didodecyl-2,2'-bithiophen-5-yl)-4-octyl-4H-bisthieno[3,2-b:2',3'-d]pyrrole) (P6) thin films were studied by X-ray diffraction and atomic force microscopy. As-cast P4 and P6 thin films exhibited poorly defined, randomly ordered lamellar structure that improved significantly after thermal annealing. Field effect transistor devices fabricated from P4 and P6 showed typical p-channel transistor behavior. Interestingly, the mobilities of as-cast, less ordered samples were much higher than those observed after annealing. The highest values of maximum and average mobilities were observed for the polymer P6 as-cast (0.21 and 0.13 cm(2) V(-1) s(-1), respectively). One of our goals was to test the idea that high mobility and excellent electrical and structural reproducibility could perhaps be achieved by the creation of amorphous pi-conjugated materials that could possess long arrange pi connectivity on the microscopic scale. The results of these studies strongly suggest that the presence of highly ordered microcrystalline structures in thin films of organic semiconductors is not necessary for excellent performance of organic transistors.     

Preparation and Characterization of Transparent and UV‐Shielding Epoxy/SR‐494/APTMS/ZnO Nanocomposites with High Heat Resistance and Anti‐Static Properties

This research is to develop transparent and UV‐shielding Epoxy/SR‐494/APTMS/ZnO nanocomposite materials with high heat resistant and anti‐static properties. Firstly, the APTMS (3‐(acryloxypropyl)trimethoxysilane) performs the silanol intermediates by hydrolysis in pH 4～5 acid solution. The inorganic anti‐static fillers of powder ZnO can be successfully coupled and crosslinked to Epoxy/SR‐494 organic matrixes with these silanols of APTMS coupling agents. The remained active ‐OH functional groups of the APTMS/ZnO complexes can network bonding with epoxy prepolymers. Therefore, the Epoxy/APTMS/ZnO complexes with good anti‐static composites will be successfully prepared. Finally, in order to improve the thermal resistant and mechanical properties, the polyfunctionalized SR‐494 (pentaery‐thritol tetracrylate) acrylate monomers and the Epoxy/APTMS/ZnO composites are chain polymerized to form an excellent cross‐linking structure of organic/inorganic nanocomposites. The chemical bonding formation and the best weight contents of reaction components are identified by FT‐IR spectra. The thermal resistance, transparence, surface electric resistance, and hardness of these nanocomposites are measured by TGA, DSC, UV‐Visible, surface resistant meter, and pencil hardness tester respectively. Experimental results show that these nanocomposites have 90% transmittance and the best Td value is 389.3 °C which is 109.0 °C and 78.6 °C higher than those of pure epoxy resin and pure SR‐494 acrylate resin respectively. The glass transition temperature is not detected below 200 °C. The surface electric resistances of Epoxy/SR‐494/APTMS/ZnO hybrid thin films are decreased from 3.14 × 10¹³ to 5.13 × 10⁷ Ω/cm². The hardness of these nanocomposites is as high as 8H, and those hybrid films have high UV‐shielding properties. The morphology structures of the hybrid thin films are estimated by SEM. The results show that the optical thin films are evenly distributed with inorganic colloidal particles and the average particle size of these nanocomposites is 45～80 nm, while the powder ZnO (particle size: 2～5 μm) was used as inorganic filler.     

UV光引发表面接枝两性离子水凝胶层的制备及抗细菌黏附性能

采用聚合和交联的SiO₂有机/无机杂化溶胶作为基材, 通过与两性离子单体层之间的过渡层, 在紫外光作用下引发杂化溶胶和两性离子单体溶液中的双键反应, 使生成的杂化层在基材和表面的两性离子聚合物之间形成辅助性黏接作用, 从而在基材表面构筑两性离子水凝胶层. 通过傅里叶红外光谱(FTIR)、 原子力显微镜(AFM)和接触角测试等方法对所制备的两性离子水凝胶层和杂化层的表面进行了表征. 以空白玻璃片为对照样品, 以金黄色葡萄球菌和大肠杆菌为试验菌, 研究了用两性离子凝胶层修饰的玻璃表面的抗细菌黏附性能. 结果表明, 在SiO₂杂化过渡层中引入线型-Si-(CH₂)₂-O-链段可有效提高杂化过渡层对基材的附着力, 并改善其柔韧性. 与对照样品相比, 用两性离子凝胶层修饰的玻璃表面具有优异的抗菌黏附性能.     

PbO-PbI2复合物膜转化的CH3NH3PbI3钙钛矿薄膜及其光电特性

有机-无机卤化物钙钛矿是一类优异的光电材料. 在过去四年内, 基于有机-无机卤化物钙钛矿的光电器件实现了超过15%的光电转换效率. 而有机-无机卤化物钙钛矿材料的可控制备是保证其在光电器件中应用的基础. 本文采用新的沉积方法在玻璃衬底表面制备了一种典型的有机-无机卤化物钙钛矿CH₃NH₃PbI₃薄膜. 其制备过程是: 采用超声辅助的连续离子吸附与反应法在玻璃衬底表面沉积PbO-PbI₂复合物膜, 之后与CH3NH3I蒸汽在110 ℃环境下反应, 将PbO-PbI₂复合物膜转化成CH₃NH₃PbI₃钙钛矿薄膜. 对CH₃NH₃PbI₃薄膜的微观结构, 结晶性及其光电性能等进行了表征. 结果表明, CH₃NH₃PbI₃薄膜呈晶态, 具有典型的钙钛矿晶体结构. 薄膜表面形貌均匀, 晶粒尺寸超过400 nm. 在可见光范围, CH₃NH₃PbI₃薄膜透过率低于10%, 能带宽度为1.58eV. 电学性能研究表明CH₃NH₃PbI₃薄膜表面电阻率高达1000 MΩ. 高表面电阻率表明CH₃NH₃PbI₃薄膜具有一定的介电性能, 其介电常数(ε_r)在100 Hz时达到155. 本研究提出了一种制备高质量CH₃NH₃PbI₃钙钛矿薄膜的新方法, 所得CH₃NH₃PbI₃薄膜可望在光、电及光电器件中得到应用.     

Nanoindentation testing of SiO<Subscript>2</Subscript>-PMMA hybrid films on acrylic substrates with variable coupling agent content

In this work we report the influence of the molar composition of the coupling agent, as well as the curing conditions on the mechanical properties of SiO₂-PMMA (polymethyl methacrylate) hybrid films deposited on organic acrylic substrates. The SiO₂-PMMA hybrid films were deposited by the sol–gel method from hybrid precursor solutions with fixed molar ratio of 1:0.25 for TEOS/MMA (Tetraethyl-orthosilicate/Methylmethacrylate) and TEOS/TMSPM (3-trimethoxysilyl propyl methacrylate) molar ratios ranging from 1:0.05 to 1:0.2. The organic compound TMSPM was used as coupling agent to enhance the bond between the organic and inorganic molecules. The wear resistance, hardness and elastic modulus of the hybrid films were determined by nanoindentation techniques and compared to the substrate mechanical behaviour. The chemical bonding in the hybrid films was analyzed by Fourier Transform Infrared spectroscopy and their transparency by optical transmission and reflection spectroscopy. The friction coefficient and sliding life of the hybrid films were also measured with a pin-on-disc tribometer. The surface morphology and roughness were determined from atomic force microscopy images. The hybrid films with lowest content of coupling agent showed the best mechanical performance in terms of hardness, friction coefficient and wear resistance keeping high optical transparency.     

Tetrahydroxy‐Perylene Bisimide Embedded in a Zinc Oxide Thin Film as an Electron‐Transporting Layer for High‐Performance Non‐Fullerene Organic Solar Cells

By introduction of four hydroxy (HO) groups into the two perylene bisimide (PBI) bay areas, new HO‐PBI ligands were obtained which upon deprotonation can complex Zn^II ions and photosensitize semiconductive zinc oxide thin films. Such coordination is beneficial for dispersing PBI photosensitizer molecules evenly into metal oxide films to fabricate organic–inorganic hybrid interlayers for organic solar cells. Supported by the photoconductive effect of the ZnO: HO‐PBI hybrid interlayers, improved electron collection and transportation is achieved in fullerene and non‐fullerene polymer solar cell devices, leading to remarkable power conversion efficiencies of up to 15.95 % for a non‐fullerene based organic solar cell.     

High‐refractive‐index thin films prepared from aminoalkoxysilane‐capped pyromellitic dianhydride–titania hybrid materials

High‐refractive‐index aminoalkoxysilane‐capped pyromellitic dianhydride (PMDA)–titania hybrid optical thin films (TP0–TP8) were synthesized and characterized in this study. They were prepared with PMDA, aminopropyltrimethoxysilane, and titanium(IV) isopropoxide via a sol–gel process followed by spin coating and multistep baking. Through adjustments in the concentration and reaction time, the inorganic content in the hybrid thin films could be as high as 59.1 wt %. The Fourier transform infrared results indicated successful bonding between the organic and inorganic moieties. However, residues of the chelating ligands were found in the hybrids with high titania contents, affecting their thermal and optical properties. Field emission scanning electron microscopy results suggested a nanosized domain of the titania segment in the hybrid materials TP0–TP8. An atomic force microscopy study suggested that the hybrid thin films had good planarization. The dispersions of the refractive index and extinction coefficient in the wavelength range 190–900 nm were studied. The refractive indices of the prepared hybrid thin films at 633 nm increased linearly from 1.567 to 1.780 with increasing titania content. However, the Abbe numbers of the hybrid thin films showed an opposite trend. Excellent optical transparence was obtained in the visible region for the prepared hybrid thin films. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3419–3427, 2001     

Metal phosphonates applied to biotechnologies: a novel approach to oligonucleotide microarrays

A new process for preparing oligonucleotide arrays is described that uses surface grafting chemistry which is fundamentally different from the electrostatic adsorption and organic covalent binding methods normally employed. Solid supports are modified with a mixed organic/inorganic zirconium phosphonate monolayer film providing a stable, well-defined interface. Oligonucleotide probes terminated with phosphate are spotted directly on to the zirconated surface forming a covalent linkage. Specific binding of terminal phosphate groups with minimal binding of the internal phosphate diesters has been demonstrated. The mixed organic/inorganic thin films have also been extended for use arraying DNA duplex probes, and therefore represent a viable general approach to DNA-based bioarrays. Ideas for interfacing mixed organic/inorganic interfaces to other bioapplications are also discussed.     

Ordered nanostructured ceramic–metal composites through multifunctional block copolymer-metal nanoparticle self-assembly

A novel strategy for fabrication of ordered ceramic–metal nanocomposites was demonstrated by multifunctional block copolymer/metal nanoparticle self-assembly. Hybrid organic–inorganic block copolymer poly(3-methacryloxypropyl-T8-heptaisobutyl-polyhedral oligomeric silsesquioxane-block-N,N-dimethylaminoethyl methacrylate) was synthesized and used as a bi-functional structure directing agent for ligand-stabilized platinum nanoparticles to form ordered organic–inorganic nanocomposites with dense loading of inorganic species in both microphase separated domains. Subsequently, thin films of the hybrid material were converted to ordered silica (ceramic)–platinum (metal) nanocomposites via UV-assisted ozonolysis. This is the first time ordered ceramic–metal nanocomposites were achieved through a bottom-up approach, opening up opportunities for the design and synthesis of a broad range of ordered inorganic–inorganic nanocomposites.     

Permeation studies on transparent multiple hybrid SiO<Subscript>2</Subscript>-PMMA coatings-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> barriers on PEN substrates

In this work we report the performance of permeation barriers based on organic/inorganic multilayer stacks. We have used PMMA-SiO₂ (poly methyl methacrylate-silica) hybrid films synthesized through a sol–gel route as organic–inorganic components, whereas Al₂O₃ thin films were used as the inorganic component. The hybrid layers were deposited by dip coating and the Al₂O₃ by atomic layer deposition (ALD), films were prepared on polyethylene naphthalene (PEN) substrates. The permeability of the films and stacks is evaluated using helium as the diffusion gas in a custom made ultra-high vacuum system. The results show that permeability for PEN is reduced from 5 × 10⁻³ g/m²-day to about 9 × 10⁻⁵ g/m²-day for the best multiple barrier evaluated. Increased barrier properties are due to the increasing in the path and hence the lag-time of the permeating gas. In particular, we report the surface roughness of the different layers and its impact on the barrier performance. The hybrid layers reduced notably the roughness of the bare PEN substrate improving the quality of the Al₂O₃ layer in the barrier. The optical transmittance of the barriers in the visible region is higher than 80% in all the studied cases.     

Synthesis and structure features of composite silicate and hybrid TEOS-derived thin films doped by inorganic and organic additives

The results of long-term researches of thin films prepared from tetraethoxysilane-derived sols containing inorganic and organic additives are systematized and analyzed. These additives give to films certain physicochemical properties for their application in electronic techniques, optics, power engineering, in biological technologies etc. The influence both inorganic (salts, acids) and organic (polyols, polyionenes, epoxy resin) additives on rheological properties and aggregate stability of sols as well as films surface morphology is minutely considered. The explanations of phenomena during film formation, including spin-coating process, are given. Essential influence of temperature and humidity on films surface morphology is shown. Influence of heat treatment modes on structure and composition of films is analyzed. Recommendations about optimization of thin films sol–gel processing are offered.     

Hybrid sol–gel thin films doped with a pH indicator: effect of organic modification on optical pH response and film surface hydrophilicity

Optical sensors for application in innovative wearable sensing systems such as textile-integrated systems and wireless sensor platforms rely on the development of low-cost multifunctional materials compatible with standard fabrication technologies. We are developing optically responsive pH sensitive sol–gel coatings for integration with a mobile wireless smart tag sensing system. For this application, we have fabricated a range of thin pH sensitive films using bromocresol green (BCG) indicator immobilised in inorganic–organic silica hybrid matrices prepared by a sol–gel method and deposited by spin-coating onto glass substrates. The surface hydrophilicity of the films were varied by using the inorganic sol–gel precursor tetraethoxysilane together with either methyltriethoxysilane, ethyltriethoxysilane, phenyltrimethoxysilane or glycidoxypropyltrimethoxysilane as organically modified sol–gel precursors, co-polymerised in different ratios. Spectral characterisation of the films was performed using visible absorption spectroscopy. The shift in absorption maxima and other spectral changes of the different matrices have been identified, and the apparent pK _app values of the immobilised BCG pH indicator determined. The surface wettability properties of the films have been studied by measuring the contact angle of water, formamide and diiodomethane which has allowed the estimation of the surface free energy (SFE) using three different models: Owens–Wendt, Wu and van Oss-Chaudhury-Good. It is shown that the SFE of the hybrid films is directly related to the type and the degree of organic modification, which in turn has a significant effect on the pH response-time of these sensing films.     

钛金属表面结构可控多层钛酸盐纳米管薄膜的制备和结构稳定性

在水热条件下, 通过控制反应温度和氢氧化钠的浓度, 在钛金属表面得到结构可控的多层钛酸盐纳米管薄膜. 根据扫描电子显微镜和高倍透射电子显微镜的观测结果, 认为钛金属表面多层钛酸盐纳米管薄膜的形成经历以下4个阶段: (1) 钛金属的水合和碱性钛酸盐水凝胶的生成; (2) 碱性钛酸盐水凝胶分解并形成层状Na₂Ti₃O₇; (3) 层状Na₂Ti₃O₇的生长; (4) 层状Na₂Ti₃O₇的劈裂和多层卷曲成轴形成纳米管. 研究了薄膜形成后机械处理对薄膜形貌和结构稳定性的影响, 并利用超声的方法实现了多层膜的层分离.     

Acrylic polymer/silica hybrids prepared by emulsifier‐free emulsion polymerization and the sol–gel process

Acrylic polymer/silica hybrids were prepared by emulsifier‐free emulsion polymerization and the sol–gel process. Acrylic polymer emulsions containing triethoxysilyl groups were synthesized by emulsifier‐free batch emulsion polymerization. The acrylic polymer/silica hybrid films prepared from the acrylic polymer emulsions and tetraethoxysilane (TEOS) were transparent and solvent‐resistant. Atomic force microscopy studies of the hybrid film surface suggested that the hybrid films did not contain large (e.g., micrometer‐size) silica particles, which could be formed because of the organic–inorganic phase separation. The Si? O? Si bond formed by the cocondensation of TEOS and the triethoxysilyl groups on the acrylic polymer increased the miscibility between the acrylic polymer component and the silica component in the hybrid films, in which the nanometer‐size silica domains (particles) were dispersed homogeneously in the acrylic polymer component. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 273–280, 2006     

Structural and mechanical properties of Laponite-PEG hybrid films

Inorganic/organic hybrids were obtained by the sol-gel type organic modification reaction of Laponite sidewalls with poly(ethylene glycol) (PEG) bearing alkoxysiloxy terminal functionality. By casting an aqueous dispersion of the hybrid, the flexible and transparent hybrid films were obtained. Regardless of the inorganic/organic component ratio, the hybrid film had the ordered structure of Laponite in-plane flat arrays. The mechanical strength of hybrid films was drastically improved by the presence of cross-linking among alkoxysilyl functionalities of PEG terminals and the absence of PEG crystallines. Hybrid films, especially those that consisted of PEG with short chain, showed good mechanical properties that originate from quasi-homogeneous dispersion of components due to anchoring of PEG terminal to Laponite sidewall and interaction of PEG to Laponite surface.