Bulk liquid crystal alignment is similar to normal crystal growth in that there is a nucleation site from whence alignment/crystallization is propagated. For liquid crystals this occurs at the interface between the liquid crystal and a surface. Some materials exhibit weak anchoring interactions with the liquid crystal phase and multiple domains of different liquid crystal director orientation are observed. Other materials interact very strongly and induce uniform alignment over large areas and macroscopic distances from the substrate surface. These materials are most useful for electro-optical devices. Surfaces typically used to align liquid crystals are polymerfilms which have been mechanically rubbed 5-9 , patterned 10, 11, 11,
and its effect on the polymer properties is essential -. This impacts the perform- ance in polymer formulations  - . The properties and applications of co- polymer materials and polymerfilms in the presence of water have been investigated extensively using several techniques including NMR-methods  -. NMR has been used to estimate the amount of water as well as water self-diffusion in porous polymer materials    . Different parts of the pore structure can be probed through the partial immobility of the liquid in pores. NMR diffusion is a very useful technique for studying the translational motion in the liquid state on the micrometer length scale  -. The translational motion of water in a porous medium is af- fected by the restriction geometry and this approval has been used to determine the surface to volume ratio, pore size, and tortuosity of porous materials -. The method has also been applied to natural biopolymers and other materials as well - .
The spectral distributions of the absorbance (A), the transmittance (T), and the reflectance (R) of the Phenol Red dye doped polymerfilms at different concentrations were plotted as a function of the wavelength in Figures 2-4, respectively. In Figure 2, the absorbance spectra of dye doped polymerfilms at the concentrations 0.30 mM and 0.40 mM exhibited broad band centered at 418 nm, while at the low dye concentration 0.05 mM, the absorbance spectrum does not show clear absorption peak. The transmittance reached to 80% - 90% for the Phenol Red dye doped polymerfilms at the low dye concentration 0.05 mM and it decreased with increased the dye concentra- tion, as shown in Figure 3 for the dye concentrations 0.30 mM and 0.40 mM. It is seen from Figure 4 that the spectrum curves of the reflectance of the Phenol Red dye doped polymerfilms show behaviors similar to those of the absorbance; this is attributed to the correlation between reflectance and the absorbance. The value of R at the low dye concentration 0.05 mM is only 5% in the visible wavelengths region and increases with increasing the dye concentration. This value reached to 21% at the dye concentration 0.40 mM; at wavelength 418 nm. The absorbance (A) of light by an optical medium is quantified by its absorption coefficient (α). This is defined by the Beer-Lambert’s law  :
Usually physical vapour deposition and chemical vapour deposition (CVD) are used to prepare thin films. Plasma polymerization, which is a luminous CVD process, is often used to make polymer thin films . The plasma polymerization may also be termed as a “chemical glow discharge” since the polymers are deposited as a thin film onto surfaces in the immediate environment of a glow discharge of the constituent organic gases. Plasma polymerization is an important technique for fabricating thin polymerfilms since it may be employed for almost any organic vapour . Plasma polymerisation results in high quality thin films that have demonstrated desirable properties including generally being homogenous, pin hole free, chemically inert, insoluble, mechanically tough and thermally stable . The quality of the film can be controlled by adjusting instrument parameters such as monomer flow rate, current density, Radio Frequency (RF) power and vacuum pressure. However, the implementation of devices based on organic thin films has been hampered by poor thermal and chemical stabilities, as well as poor mechanical properties . There remain many challenges in developing polymer thin films of high quality for implementation in electronic and optical applications.
The TGA curves of polymer alloy films are wider and show that the weight loss occurs in more than two steps. The first weight loss indicates the evaporation of water. The second loss occurs above 385 0 C with a maximum decomposition rate at 457 0 C and 489 0 C for polymer alloy films containing calcium polymethacrylates. It was observed that the initial temperature for second stage degradation is higher with higher MMA content in polymer film. Table-3
converted into heat. This assumption was confirmed experimentally for polyethylene terephthalate (PET) (Andrianova et al. 1978). However, usually some fraction of the produced work is accumulated as internal energy. The typical ratio of the generated heat to the produced work, Q / A , for polymer drawing is 0.7 to 0.9 (Godovsky 1992; Salamatina et al. 1989). The ratio Q /А for low- density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), and polyamide-6 does not depend on the drawing rate (Godovsky 1992). In contrast, for amorphous PET, the ratio Q /А increases from 0.95 at low drawing rates, V , to 1.3-1.35 at V = 120 mm/min. Q /А exceeds unity due to crystallization of PET at high drawing rates (Godovsky 1992).
As devices are being developed with a view towards making them smaller, thinner and lighter in dimension, thin polymerfilms are found to be in more stringent demand in various applications, such as diffusion bar- riers, dielectric coatings, electronic packing, and so on . Therefore, understanding the elastic modulus in confined geometries, such as in thin films, is critical to the stability of the structures of the actual devices. A growing demand exists for the determination of the mechanical properties of thin films and coatings at a rapid pace. Recent researches primarily focusing on the confinement effect of the glass-transition temperature T g in thin films [2-7], have presented inconsistent
In order to hot emboss the polymerfilms, dry film photoresist stamps were employed, which were rapidly and simply fabricated without the use of cleanroom facilities. These photoresist layers also proved effective as an etch mask for deep glass etching, which enabled us to produce embossing stamps made from glass without having to employ more complicated multi-layer masks. Although the production of shallow etched feature using thin resist masks is relatively straightforward, the production of deep etched structures is notoriously difficult because most masking materials are either attacked by the HF, detach from the substrate or contain
Exposure of the precursor to the highly reactive plasma environment initiates a wide range of reactions that include fragmentation, rearrangement, oligomerisation, and polymerisation. The extent of precursor fragmentation is highly dependent on the amount of energy delivered into the plasma chamber, which is in turn, directly related to the applied RF power. The dissociation is initiated by highly energetic electrons, rather than by means of thermal excitation or chemical reaction, giving rise to a unique assortment of chemically reactive species that may not be obtainable under other processing conditions. These reactive species can undergo recombination inside and outside of the plasma region, e.g., at the surface of the substrate, enabling the formation of the polymer thin film on its surface. Given the abundance of chemically-diverse species, and the presence of functional groups typically associated with conventional polymerisation, the polymerisation process follows multiple pathways, including conventional polymerisation, as well as fragment- recombination triggered by the plasma-generated and surface-attached reactive ions, and free radicals. This gives rise to a more complex polymer structure, potentially rich in free radicals trapped in a three dimensional network. The surface topography of the thus-formed polymer is influenced by the intensity of plasma-generated ion bombardment, which is again linked to the applied RF energy. Considering the intimate link between biological activity of the surface and its surface chemistry and nanoscale topography, it is possible that the combination of these properties in polymerfilms fabricated at 10 W prevent bacterial fouling. Chemical characterisation showed that these surfaces bared a larger proportion of hydroxyl functional groups compared to the samples fabricated at 50 W. It has previously been shown that S. aureus cells preferentially attached to surfaces bearing carboxylic and methyl functional groups than those containing –OH functionality . This is also supported by the thermodynamically predicted preference of hydrophobic cells for hydrophobic substrates. 5. Conclusions
Herein, we are interested in studying the influence of a honeycomb structure of Laponite clay discs on the water barrier properties of the nanocomposite polymerfilms made from poly(styrene-co-n-butyl acrylate) latex particles armored with the clay discs. The advantage of using armored particles is that the thin layer of silicates is pre-positioned around the polymer particles, hereby enforcing the formation of a continuous silicate network. This control of arrangement of the Laponite discs throughout the nanocomposite “soft” poly(styrene-co-n-butyl acrylate) films will potentially show intriguing effects on both the water vapor adsorption/release profiles, and also the water vapor barrier properties. An important property of this silica-based ceramic material is its capacity to retain and adsorb water molecules and its potential barrier toward oxygen permeability. 14 These two factors are of key importance for example for the food packing industry. In our study we try to understand the phenomenon of water adsorption/desorption in waterborne hybrid polymerfilms. In addition water vapor barrier properties through the hybrid polymer nancomposites are investigated.
All the electrochemical measurements were performed using a potentiostat /galvanostat (Autolab 101) equipped with NOVA software at room temperature. Perkin Elmer’s Fourier transform infrared (FTIR) spectrometer designed with Universal Attenuated Total Reflectance (UATR) accessory was used to study the composition of the films. The Raman spectra of the films were recorded on Alpha300 R microscopic confocal Raman spectrometer (WITec GmbH) equipped with a 633 nm laser line. Surface morphology of the polymerfilms were determined via scanning electron microscope JEOL JSM 6400 and Leo 1455 VP-SEM model.
Electrochemical experiments were performed using BAS100B and BASi Epsilon electrochemical analyzers and a three – electrode cell a glassy carbon disc working electrode (GCE, = 3.0 mm), a Pt wire auxiliary electrode, and a second Pt wire pseudo reference electrode. Spectroelectrochemical experiments were performed using a specially designed quartz cuvette cell (1 mm 10 mm, Bioanalytical Systems, Inc) and the Nicolet E100 UV/vis absorption spectrometer (Thermo-Electron Corporation). In this case the working electrode was an ITO coated glass and the auxiliary electrode was a platinum-gauze. The ITO/glass (7 mm 50 mm 0.6 mm, R ≤ 10 Ω) was supplied by Delta Technologies Inc (Loveland, USA) and used as received after rinsing with deionized water. Atomic force microscopy (AFM) imaging of polymerfilms electrodeposited on the ITO electrodes were done using a Veeco NanoMan V model AFM microscope with a silicon tip of spring constant 1-5 N/m and resonance frequency 60 – 100 kHz.
AFM studies of the topographical features of the sur- faces, Figure 3a-c, revealed that the SAM-Au/quartz sur- faces were uniformly coated with MIP and REF films. The roughness values for the REF and MIP films were 20.6 and 20.3 Å, respectively. Ellipsometry was used to determine the average thicknesses of the films 33.95 ± 4.40 Å and 40.28 ± 12.40 Å (standard error of the mean) for MIP and reference polymers, respectively (n = 3). Im- portantly, as shown by SEM-studies, the polymerfilms were uniformly coated over the substrate (Figure 3d). FT-IR studies on the polymerfilms revealed that the MIP and REF copolymers both possessed functionalities corresponding to the monomers, MBA and AMPS (Figure 3e). Typical ν(N-H) stretching was observed as a broad peak at around 3300 cm −1 . In addition, the bands arising from ν(C = O) and δ(N-H) of MBA were located at 1668 and 1531 cm −1 , respectively. The presence of the sulfonic acid moiety (AMPS) can be inferred from the asymmetric as well as symmetric stretches of ν(SO 2 )
Thin polymerfilms display distinct differences from their bulk matrix, including those related to crystallization [1, 2], physical cross-linking in polymers , thermal expansion coefficients [4–7], and physical aging [8–12]. Decreasing the thickness of thin films below 10 nm, the physical and chemical properties of ultrathin films are significantly dif- ferent in comparison with thin films due to the thickness confinement effect [13–15]. To explore such a thickness- dependent effect, a great deal of effort has been devoted to investigating the molecular mobility and relaxation dynamics within ultrathin polymerfilms [14, 16–18]. Previous studies have revealed that the surface relaxation dynamics in ultrathin films were apparently different from that in bulk materials and normal thin films [19, 20]. The glass transition temperature (T g ) of ultrathin films was far
Increasing attention is being directed towards the modification of existing polymers to produce novel materials with desired properties. 27,53 Nanocomposites are the most recent class of composite materials, defined as particle-filled polymers containing dispersed units, such as silica nanoparticles, semiconducting nanocrystals, or nanotubes, with at least one dimension in the nanometer range. Nanocomposites have been reported to improve optical, thermal and mechanical behaviour of the polymer, as well as other properties. 32,53 QDs can be functionalized with specific organic ligands to improve their compatibility with polymer systems in order to produce nanocomposites with improved properties. 40,46 However, the performance of QDs have not been examined in polymerfilms suitable for greenhouse applications. The proposed experimental nanocomposite greenhouse films have the potential to enhance the optical properties of greenhouse plastic by adjusting the naturally available light spectrum in order to improve crop quantity and quality without additional electricity input, creating more efficient, sustainable greenhouses.
The surface morphology of the plasticized polymer complexes were investigated by using scanning electron microscope (JOEL JSM-6380LV) at 20 kV. The polymerfilms were gold coated under vacuum by electron beam gold palladium source (80% Au, 20% Pd) by JEOL coater (Model JFC-1600) to make them conducting and mounted onto circular aluminum stubs with double side sticky tapes. Fourier transform infrared (FT-IR) spectra of the prepared samples were recorded in the wavenum- ber range of 400 - 3000 cm –1 using single beam FT-IR
at the center of the film would remain primarily highly ductile. These results are significant as until now there has been very limited research in non-block copolymers that consider how the vertical segregation within a film effect overall film ductility. Importantly, the improved mechanical capability of the blend system does not degrade charge transport characteristics within the film, but instead enables strain oriented films. Mobility in the direction of applied strain increases compared to the unstrained film. The resulting anisotropy is a result of increased polymer backbone alignment in the direction of applied strain, where charge transport is the most efficient. A significant channel length dependence phenomena arises within the 1:1 PCDTPT:P3HT film but is significantly less dominant in the 1:4 PCDTPT:P3HT film. This difference in channel length behavior between the two blend systems can be directly attributed to the nanoscale fractures around the PCDTPT aggregates. As charge transport occurs within the film it must hop between chains and disordered regions. For short channel lengths the amount of hops that the charge must undertake is minimal. As the channel length increases the amount of chains, discontinuities from fractures and grain boundary disorder the charge must overcome increases. Thus, it is inevitable that some charges will be lost and charge transport for these longer channel length devices will be significantly less efficient.
cole) plots. It was observed that the magnitude of conductivity increased both with the increase in the salt concentration and the temperature. The charge transport of these electrolytes is mainly due to ions which were confirmed by the transference number experiment. Using this electrolyte, cells were fabricated and their discharge profiles were studied under constant load. Several cell parameters associated with the cells were evaluated and compared with earlier reports. Keywords: Polymer blend electrolyte, XRD analysis, AC conductivity studies, Transference numbers, Discharge profiles.