A periodic striping pattern with microscale pore size is observed on the surface of thin films prepared by spin-casting from a polystyrene (PS) and polyethylene glycol (PEG) blend solution. The pattern is created by the convection generated by thermal gradients in the solution between the substrate and film solution during solvent evaporation, the radial flow of the spin-coated solution, and the primary and secondary phase separation of the PS and PEG solutions. The formation mechanism of the periodic porous stripe pattern is discussed, wherein the effects of the polymer blend weight ratio, polymer concentration, and drying rate on the formation of the periodic porous striping pattern are investigated using scanning electron and atomic force microscopy. 相似文献
This article presents a simple, fast and low-cost method to fabricate a flexible UV light photomask. The designed micropatterns were directly printed onto transparent hybrid composite film of biaxially oriented polypropylene coated with silica oxide (BOPP-SiOx) by an inkjet printer. Compared to the conventional chrome-mask, it is of advantages such as suitable for non-planar substrates, scalable for large area production, and extreme low cost. Combined with the confined photo-catalytic oxidation (CPO) reaction, the printed flexible BOPP-SiOx photomask was successfully used to pattern the shape of wettability of organic polymer surfaces, and then polyaniline patterns were deposited on the modified substrates with strong adhesion. With the above photomasks, the polyacrylic acid graft chains were duplicated on the poly (ethylene terephthalate) (PET) and BOPP substrates by photografting polymerization. We grafted polyacrylic acid (PAA) on a non-planar plastic substrate with this soft and thin plastic photomask. Scanning electron microscopy (SEM) and optical microscopy were used to characterize the surface morphology and thickness of ink layers of the printed photomask. Optical microscopy was used to characterize the deposition polyaniline micropatterns. It was found that the desired patterns were precisely printed on the modified polymer films and were applied in modifying organic polymer substrates. The printed photomask could be exploited in the fields such as prototype microfluidics, micro-sensors, optical structures and any other kind of microstructures which does not require high durability and dimensional stability. 相似文献
The performance of organic photovoltaic devices based upon bulk heterojunction blends of donor and acceptor materials has been shown to be highly dependent on the thin film microstructure. In this tutorial review, we discuss the factors responsible for influencing blend microstructure and how these affect device performance. In particular we discuss how various molecular design approaches can affect the thin film morphology of both the donor and acceptor components, as well as their blend microstructure. We further examine the influence of polymer molecular weight and blend composition upon device performance, and discuss how a variety of processing techniques can be used to control the blend microstructure, leading to improvements in solar cell efficiencies. 相似文献
The plasma polymerization of aniline on different surface functionlized low-density polyethylene (LDPE) substrates was investigated, and the resulting polymer was characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. The results showed that the structure of plasma-polymerized polyaniline was rather different from polyaniline synthesized by conventional chemical and electrochemical methods. This difference may be due to extensive coupling reactions and cross-linking reactions during the plasma polymerization process. The use of acrylic acid graft copolymerized LDPE substrate significantly enhanced the adhesion of the polyaniline to the substrate over that observed with pristine LDPE. The plasma polymerized polyaniline can be rendered electrically conductive if the polymerization is carried out on a polystyrenesulfonic acid-coated LDPE substrate. Conductivity can also be induced by acid protonation of the polyaniline by HClO(4). The reaction of the plasma-polymerized polyaniline with viologen grafted on the substrate under UV irradiation and with AuCl(3) and Pd(NO(3))(2) in acid solutions was also investigated. 相似文献
The surface structure of thin polymer blend films of deuterated polystyrene (dPS) and polyparamethylstyrene (PpMS) after annealing above the glass transition temperature was investigated. With scanning force microscopy (SFM) the surface topography originated by a dewetting process is detected. The sample surface is covered with small droplets consisting of several polymer molecules. Utilizing grazing incidence small angle neutron scattering (GISANS) the topographical information as well as the in‐plane composition is probed. For thin confined blend films a substructure of the droplets resulting from an additional phase separation process at different length scales is detected. 相似文献
Poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene), PBTTT, is a semiconducting polymer that forms thin film transistors (TFTs) with high field effect mobility on silicon dioxide dielectrics that are treated with alkyltrichlorosilanes ( approximately 0.2 to 0.5 cm2/V s) but forms TFTs with poor mobility on bare silicon dioxide (<0.005 cm2/V s). The microstructure of spin-coated thin films of PBTTT on these surfaces was studied using synchrotron X-ray diffraction and atomic force microscopy. PBTTT crystallizes with lamellae of pi-stacked polymer chains on both surfaces. The crystalline domains are well-oriented relative to the substrate in the as-spun state and become highly oriented and more ordered with thermal annealing in the liquid crystalline mesophase. Although the X-ray scattering from PBTTT is nearly identical on both surfaces, atomic force microscopy showed that the domain size of the crystalline regions depends on the substrate surface. These results suggest that electrical transport in PBTTT films is strongly affected by the domain size of the crystalline regions and the disordered regions between them. 相似文献
Silicon substrates with (100) orientation were modified with amino-silane self-assembled monolayer (SAM) to provide amino (NH(2)) moieties at the substrate surface. Self-organization of polyaniline during chemical polymerization, on this modified surface, leads to the growth of highly oriented films at the substrate-polymer interface. The morphology studied using scanning electron microscopy and atomic force microscopy revealed the formation of polymer film with well faceted pyramidal crystallites. XPS and FTIR spectroscopy were used to analyze the chemical structure of the film. X-ray diffraction measurements show the crystalline nature of the polyaniline, whose lattice parameters are in agreement with the reported values. This study underlines the importance of a SAM in deciding the structure and morphology of the deposited polymer. 相似文献
In the present work broadband dielectric relaxation spectroscopy measurements were employed to investigate the dielectric properties of polymer composites. A polyethylene/polyoxymethylene (PE/POM) thermoplastic blend was used as a matrix, while the inclusions were iron (Fe) particles. For comparison, the two pure polymers- PE and POM- were used as a matrix, too. In the PE/POM-Fe composites, the polymer matrix is two-phase and the filler particles are localized only in the POM phase, resulting in an ordered distribution of the dispersed filler particles within the blend. In PE-Fe and POM-Fe composites, the filler spatial distribution is random. The behaviour of all the composites studied is described in terms of the percolation theory. The PE/POM-Fe composites, based on the PE/POM blend, demonstrate different electrical behaviour compared to that of POM-Fe and PE-Fe systems. The percolation threshold value of the PE/POM-Fe composites was found much lower than that of the other two systems. The results were related to the microstructure of the composites. A schematic model for the morphology of the composites studied has been proposed. This model explains the peculiar behaviour of the PE/POM-Fe composites by taking into account the ordered distribution of the filler particles in a binary polymer matrix. Optical microscopy photographs confirm this model. 相似文献
Summary: We report an artful method to form a stable pattern of chiral polyaniline nanocomposites (CPANs). It consists of the preparation of a diazoresin (DR)/poly(acrylic acid) (PAA) thin buffer layer on an Si substrate by self‐assembly, followed by the deposition of a multi‐layer film by spin‐assembly, leading to the formation of a (DR/PAA)2DR/(CPAN/DR)n film on the substrate. After selective exposure to UV light through a photomask and the development process, a defined pattern is formed.
Scanning electron microscopy image of the patterned (CPAN/DR)5 thin film on Si wafer. 相似文献
Structural regular polyaniline was synthesized via a modified-chemical oxidative polymerization reaction. Highly hydrophilic polyaniline (PANi) and polyaniline-poly(vinylidene fluoride) blend (PANi-PVDF) membranes were prepared by solution casting and phase inversion techniques. Both of the mechanical and filtration properties of the membranes depend on the polymer composition and doping level of the blends. The elasticity of the membrane is greatly improved upon introducing poly(vinylidene fluoride) into the blend. The water permeability of the blend membranes is further enhanced when the membranes are doped with hydrochloric acid. The PANi-PVDF blend membranes are capable of recovering metallic gold from the acid/halide leaching streams spontaneous and sustainably, and are promising candidates for wastewater treatments in electronic industries. 相似文献
In the present work, physico-chemical properties of conducting polyaniline (PANI) prepared by laccase-catalyzed oxidative polymerization in water dispersions of sodium dodecylbenzenesulfonate micellar solutions were studied. The polymer was characterized using FTIR spectroscopy, cyclic voltammetry, termogravimetry, transmission electron microscopy, and electron diffraction. The antistatic properties of the obtained polyaniline were also studied. 相似文献
Two-dimensional palladium (Pd) nanostructures have been fabricated by electrochemical deposition of Pd onto an indium tin oxide glass substrate modified with a thin flat film of polypyrrole or a nanofibril film of polyaniline. The experimental results demonstrated that the morphology of Pd nanoparticles strongly depended on the properties of conducting polymers and the conditions of electrochemical deposition. Two-dimensional nanostructures composed of flower-like (consisting of staggered nanosheets) or pinecone-like Pd nanoparticles were successfully synthesized. They can be used as substrates for surface-enhanced Raman scattering after partly decomposing the polymer components by heating in air, and the enhancement factor of the substrate composed of flower-like Pd nanoparticles was measured to be as high as 105 for 4-mercaptopyridine. 相似文献
Polymer/nanoparticle composite films are receiving growing attention thanks to their potential for application in ultra-thin
electronic and optical devices. Polymer blend demixing has been shown to be a suitable technique for the structuring of polymer
thin films and the patterning of nanoparticles (NP) within them. In this work we show that the morphology of thin polymer
films made by spin-casting a polymer blend solution containing NP fillers on a surface depends strongly on the concentration
of NP fillers. More specifically, polystyrene/polymethylmethacrylate (PS/PMMA) films formed from a toluene solution, and which
demix following a nucleation and growth mechanism, were studied. It was found that both the height and the surface density
of PMMA domains increased as the concentration of CoPt:Cu NPs in the film was increased. We find that similar effects are
induced in a NP-free PS/PMMA demixed film upon increasing the molecular weight of the PS molecules. This suggests that under
certain conditions the NPs and the polymer molecules in the blend do not behave as separate species but form aggregates. 相似文献