Transparent Poly Vinyl Alcohol Research Articles

Phosphor‐Loaded Triboelectric Film‐Based Multipurpose Triboelectric Nanogenerators for Highly‐Efficient Energy Harvesting, Sensing, and Self‐Illumination Applications

AbstractA novel approach is proposed for combining phosphor materials with triboelectric nanogenerators (TENGs) for mechanical energy harvesting and illumination applications. For this purpose, strongly reddish‐orange‐emitting Ba0.5Sr0.5Nb2O6:0.25 mol Eu3+ (BSNb:0.25Eu) phosphor materials are synthesized. The photoluminescence properties of the synthesized BSNb:0.25Eu are analyzed. The synthesized BSNb:0.25Eu is utilized as a dielectric filler inside a polydimethylsiloxane polymeric film due to its high dielectric properties to improve the overall dielectric properties of the composite film (CF). TENG devices are fabricated using phosphor‐loaded CFs as the tribonegative layer, transparent polyvinyl alcohol as the tribopositive layer, and aluminum as the conductive electrode. All the TENGs operate in a contact‐separation mode, and the highest electrical output is attained by optimizing the phosphor filler concentration in the CF. The optimized TENG exhibits excellent stability in long‐term operational tests, under varying harsh ambient temperatures. Indium tin oxide sputtered on both triboelectric films as an electrode and combined with a transparent hard substrate to obtain a fully transparent TENG. A self‐illuminating TENG (SI‐TENG) is fabricated by integrating near‐ultraviolet light‐emitting diodes between two identical TENGs. The SI‐TENG can harvest the mechanical energy available in the surrounding environment and illuminate it as a light source. Additionally, the proposed phosphor‐loaded polymer films can be employed for optical thermometry and mechanical energy harvesting via SI‐TENG on a large scale.

Efficient Hydrolysis of Cottonseed Oil with Amano Lipase Entrapped on Hydrolysed Polyvinyl Alcohol Gel Pellets Optimized via Factorial Design

Abstract: The aim of this study was to obtain the optimum hydrolysis of cottonseed oil via immobilized lipases (Lipases Rhizopus oryzae, SL from Pseudomonas (Burkholderia) cepacia, Amano lipase from Mucor javanica, ANL from Aspergillus niger lipase, TL from Pseudomonas stutzeri, QLM from Alcaligenes sp., Triacylglycerol lipase (EC 3.1.1.3), PL from Alcaligenes sp., AL from lysosomal acid lipase, Candida antarctica (CA), and Candida cylindrea (CC)) on hydrolysed polyvinyl alcohol (PVA) gel pellets. : The production of free fatty acids by the hydrolysis of triglycerides from several sources is an important component in the economic exploitation of naturally produced renewable raw materials. : Herein, various lipases, including Rhizopus oryzea, SL, Amano lipase from Mucor javanica, ANL, TL, QLM, EC, PL, AL, CA, and CC were screened for optimum hydrolysis of cottonseed oil. Following the selection of lipase for hydrolysis of cottonseed oil, transparent PVA gel was synthesized by physical gelation method employing Dimethyl sulfoxide and a water system. In the last step, immobilization of selected lipase i.e. Amano lipase for cotton seed oil was carried out at 4oC for one hour. After successful synthesis and immobilization, the PVA gel was characterized by FTIR and SEM analysis. Finally, factorial design was employed for optimization of experimental variables such as pH, time and amount of cotton seed oil hydrolysis by lipase immobilized PVA. : The obtained results indicated that lipase Amano was found better with higher free fatty acids (FFA) yields (with 98.38%) in 5 hours using 3 g of cottonseed oil, suggesting that PVA immobilized Amano lipase is an efficient catalyst to hydrolyze the cottonseed oil. : The overall study indicated that hydrolysed PVA gel is an effective biocompatible solid support for immobilization of lipases to obtain higher FFA from cottonseed oil following hydrolysis reaction.

Antibacterial Activity of PVA Hydrogels Embedding Oxide Nanostructures Sensitized by Noble Metals and Ruthenium Dye.

Nanostructured oxides (SiO2, TiO2) were synthesized using the sol-gel method and modified with noble metal nanoparticles (Pt, Au) and ruthenium dye to enhance light harvesting and promote the photogeneration of reactive oxygen species, namely singlet oxygen (1O2) and hydroxyl radical (•OH). The resulting nanostructures were embedded in a transparent polyvinyl alcohol (PVA) hydrogel. Morphological and structural characterization of the bare and modified oxides was performed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), UV-Vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). Additionally, electrokinetic potential measurements were conducted. Crystallinity data and elemental analysis of the investigated systems were obtained through X-ray diffraction and X-ray fluorescence analyses, while the chemical state of the elements was determined using XPS. The engineered materials, both as simple powders and embedded in the hydrogel, were evaluated for their ability to generate reactive oxygen species (ROS) under visible and simulated solar light irradiation to establish a correlation with their antibacterial activity against Staphylococcus aureus. The generation of singlet oxygen (1O2) by the samples under visible light exposure can be of significant importance for their potential use in biomedical applications.

Flame‐resistant and tough polyvinyl alcohol film with ultraviolet‐absorbing capacity

AbstractFireproofing the polyvinyl alcohol (PVA) membrane is an essential and urgent reinforcement to ease the restriction in flame‐resistant requirements. The traditional method by the physical and heterogenous introduction of a large number of metal hydroxides, halogenated and organic compounds efficiently enhance the flame‐retardancy but severely weakens the biocompatibility, mechanical strength, and transparency of PVA membranes. In this work, two bio‐extracted compounds, phytic acid (PA) and creatine (CR) are employed to construct a fireproof, tough and transparent PVA membrane. The LOI of the PVA/PACR membrane increases from 18% to 30% and reaches a V–0 grade in UL‐94 testing. Meanwhile, the mechanical strength receives 20% reinforcement due to a chemical crosslinking between PVA, PA, and CR. Intriguingly, unsaturated chemical bonds from PA and CR endow a favorable UV‐absorbing capacity to the PVA membrane, which will benefit the anti‐aging and food freshness retaining demands in advanced packaging applications.

Optically transparent polyvinyl alcohol composite film obtained by self-reinforcing and self-toughening with electrospun polyvinyl alcohol nanofibers: A solution processing strategy

Optically transparent polyvinyl alcohol (PVA) films with high tensile strength and toughness are urgently needed in optical field. However, the combination of good optically transparency and excellent mechanical properties is still an obstacle for the PVA films. Herein, PVA composite film obtained by self-reinforcing and self-toughening with electrospun PVA nanofibers possessing various solubility via a solution strategy is proposed to tackle this challenge. The uniaxially aligned PVA nanofibers were electrospun by a narrow roller; thereafter, the PVA composite films were fabricated by solution impregnation technique and mould pressing. Owing to the strong interface binding, entangled molecular chains, and close refractive index between PVA nanofiber and PVA matrix, the as-prepared PVA-based composite film showed satisfactory light transmittance of above 85% in the 400–800 nm wavelength range with the tensile strength and elongation at break achieving 70 MPa and 160.1%. This work proposed a new solution-based strategy to efficiently fabricate PVA composite films for optical applications.

Using novel polymer microspheres as an efficient UV filter and blue light converter for constructing multifunctional transparent polyvinyl alcohol films

Overexposure to ultraviolet (UV) light can pose a threat to human health and lead to the photodegradation of organic materials, thereby there is great interest in the development of UV-shielding and UV-to-visible light converting materials. In this study, a novel polymer microsphere with both UV-shielding and blue-light-emitting characteristics was fabricated by grafting disodium 4,4′-bis[(4-anilino-6-hydroxyethylamino-1,3,5-triazin-2-yl) amino] stilbene-2,2′-disulphonate (VBL) onto poly (maleic anhydride-co-α-methyl styrene) (PMAS) microspheres via an esterification reaction. The as-prepared PMAS-VBL microspheres were then incorporated into polyvinyl alcohol (PVA) to prepare composite films. The introduction of PMAS-VBL endowed PVA with excellent UV-shielding and fluorescent properties, which are mainly derived from the UV-to-blue light converting ability of VBL. PVA films containing 7 wt% PMAS-VBL microspheres can block almost 100% UV light while the visible light transmittance was maintained at 66.9% and the absolute quantum yield of the films reached up to 74.26%. This work opens up a new pathway for fabricating UV filters and blue light converters, which are very promising for a diversity of UV-shielding and fluorescence-based applications.

Tough, Transparent, and Slippery PVA Hydrogel Led by Syneresis.

Slippery and transparent polyvinyl alcohol (PVA) hydrogels with mechanical robustness exhibit broad applications in artificial biological soft tissues, flexible wearable electronics, and implantable biomedical devices. Most of the current PVA hydrogels, however, are unable to integrate these features, which compromises its performance in biological and engineering applications. To achieve such purpose, herein, a novel tactic is proposed, salting-out-after-syneresis of PVA, to realize a mechanically robust and highly transparent slippery PVA hydrogel. The syneresis of PVA sol is first conducted to form highly dense and transparent PVA polymer networks, then the salting-out effect tunes the aggregation of the polymer chains to rapidly induce the phase separation and crystallization. The resultant hydrogels show the transparency up to 98% in the visible region, the tribological coefficient down to 0.0081, and the excellent mechanical properties with strength, modulus, and toughness of 26.72±1.05, 6.66±0.29MPa, and 55.21±1.62MJm-3 , respectively. To reveal the potentials, PVA contact lens that combine remarkable lubrication, anti-protein adhesion, biocompatibility, and drug-loading functions are demonstrated. This strategy provides a simple and new avenue for developing the mechanically robust, transparent, and hydrated hydrogels, showing the potential in biomedicine and wearable devices.

Light-enhanced transparent hydrogel for uric acid and glucose detection by four different analytical platforms

The lack of solid-phase media limits the portability of colorimetric sensing platforms. In this study, a series of transparent polyvinyl alcohol (PVA) hydrogels encapsulated antimony tin oxide nanoparticles (ATO NPs) and 3,3′,5,5′-tetramethylbenzidine (TMB) were developed as the solid-phase sensing media for glucose and uric acid. Under the conditions of H2O2 and UV light, the hydrogel presented a multicatalytic ability (photo Fenton-like and peroxidase-like activities), which accelerated the oxidation of TMB, turning the hydrogel from colorless to blue and finally enhancing the detection signal. The plasticity of the hydrogel allowed it to be designed into various shapes (membrane, microsphere etc.) to adapt multiple detection platforms (a liquid/solid-phase UV spectrophotometer, a NanoPhotometer, and smartphone spectroscopy). The hydrogel sensing media exhibited excellent tunability and enhanced the photocatalytic ability. The proposed material was successfully applied to detect glucose and uric acids in real samples by four detection platforms to evaluate its practicability.

A Polyvinyl Alcohol-Tannic Acid Gel with Exceptional Mechanical Properties and Ultraviolet Resistance.

Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)-tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by a combination of freeze-thaw treatment and a tannic acid compound. The effect of tannic acid on mechanical properties of prepared PVA-TA gels was investigated and analyzed. When the mass fraction of PVA was 20.0 wt% and soaking time was 12 h in tannic acid aqueous solution, tensile strength and the elongation at break of PVA-TA gel reached 5.97 MPa and 1450%, respectively. This PVA-TA gel was far superior to a pure 20.0 wt% PVA hydrogel treated only with the freeze-thaw process, as well as most previously reported PVA-TA gels. The toughness of a PVA-TA gel is about 14 times that of a pure PVA gel. In addition, transparent PVA-TA gels can effectively prevent ultraviolet-light-induced degradation. This study provides a novel strategy and reference for design and preparation of high-performance gels that are promising for practical application.

Controllable construction of laser-induced colorful patterns based on thermal energy transfer between carbon nanotubes substrate and polymer interface

Laser irradiation technology has been widely used in the field of polymer material patterning. Improving the laser response of polymer is the key to realize laser patterning. The traditional doping process cannot achieve pattern colors other than black and white, and will affect the performance of polymer matrix. In this paper, the locally controllable laser-induced pattern transfer between the substrate and the polymer interface is realized by preparing a carbon nanotubes (CNTs) substrate with high photothermal conversion effect. The laser beam was irradiated on the interface between the CNTs substrate and the transparent polyvinyl alcohol (PVA) film. The CNTs substrate absorbed laser energy and transferred to PVA film to produce a carbonized pattern in situ. Further, colorful inorganic pigments can be transferred from the substrate to the polymer surface layer based on this interfacial transfer technique, which makes a breakthrough to realize the colorful laser-induced pattern of polymers. Moreover, the repeatability test further proves the reliability and recycling performance of the CNTs substrate. This study provides a positive approach for the industrialization of laser-induced colorful patterns on polymers.

Multicolor Emitting Carbon Dot-Reinforced PVA Composites as Edible Food Packaging Films and Coatings with Antimicrobial and UV-Blocking Properties.

Active food packaging has become attractive because of the possibility to provide a longer shelf-life by loading functional agents into the packages to maintain the quality of food products. Herein, photoluminescent and transparent polyvinyl alcohol (PVA)-based composites embedding multicolor fluorescent carbon dots (CD/PVA) were prepared by the solvent casting method. The prepared CDs emit a strong and stable fluorescence in solution while the CD/PVA composite films were transparent, flexible, and showed UV-blocking activity with a strong fluorescence emission. Blue color-emitting CDs showed the highest UV blockage at UVA (87.04%), UVB (87.04%), and UVC (92.22%) regions while PVA alone absorbed only less than 25% of the light in all UV regions. UV blockage capacity was shown to be decreased by half, in line with the emission color shift from blue to red. Thermal properties of the PVA film were improved by the addition of CDs to the polymer, and in vitro cell viability tests showed that none of the CDs were cytotoxic against the human lung fibroblast healthy cell line (MRC-F cells) when integrated into the PVA. The antimicrobial activity of CD/PVA nanofilms was qualitatively determined. The prepared films exhibited good antimicrobial activity against both Gram-positive and Gram-negative bacteria with mild antioxidant and metal chelating activity, and significant inhibition of biofilm formation with a strong link with emitted color and the concentration of the composites. Green- and red-emitting CD/PVA with the highest antimicrobial activity were then analyzed and compared with the plane PVA employing their effect on the shelf-life of strawberries as a model for perishable foods. Fresh strawberries dip coated with CD/PVA and PVA were monitored over time, and virtual evaluations showed that CDs/PVA film coating resulted in reduced weight and moisture loss and significantly inhibited the fungal growth and spoiling for over 6 days at RT and 12 days at fridge conditions maintaining the visual appearance and natural color of the fruit. The findings in this work indicated the potential of reported CD as non-cytotoxic, UV-blocking antimicrobial additives for the development of edible coatings and packages for their use in the food industry, as well as pharmaceutical and healthcare applications.

Structural and photoluminescence properties of a trivalent rare earth Sm ion-doped PVA/PVP blend polymer films

Transparent polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP) and various concentrations of Sm3+ ion-doped PVA/PVP blend-polymer films were prepared using the solution cast method. The structural properties were studied by using XRD and FTIR. Optical UV-Vis, photoluminescence, and decay studies were carried out for prepared PVA/PVP blend polymer films. The XRD confirms the structural change in PVA/PVP blend-polymer with the doping of Sm3+ ion. From FTIR, Sm3+ ion forms the complex formation within the PVA/PVP polymer structure. The allowed band gap decreased from 5 to 4.6 eV, and the refractive index increased from 2.4 to 2.45, increasing Sm3+ ion concentration. From the energy band gap, the bonding parameters ( and δ) were calculated to find the covalent/ionic bond nature of the prepared polymer films. The emission spectra were measured for Sm3+: PVA/PVP with the excitation of 402 nm wavelength (6H5/2→4F7/2). 4G5/2→ 6H7/2 shows maximum intensity at 0.4 wt % of Sm3+, and beyond concentration, quenching was noticed. It is observed from the decay curve that the lifetime of PVA/PVP samples doped with Sm3+ at all concentrations decreases with the increase of Sm3+ ion concentration. It was noticed from CIE chromaticity that Sm3+: PVA/PVP blend polymer films are more appropriate for enhancing reddish-orange photonic emission. Based on the above results, Sm3+: PVA/PVP blend polymer films are suitable for reddish-orange luminescent applications.

Transparent polyvinyl-alcohol cryogel as immobilisation matrix for continuous biohydrogen production by phototrophic bacteria

BackgroundPhototrophic purple non-sulfur bacteria (PNSB) have gained attention for their ability to produce a valuable clean energy source in the form biohydrogen via photofermentation of a wide variety of organic wastes. For maturation of these phototrophic bioprocesses towards commercial feasibility, development of suitable immobilisation materials is required to allow continuous production from a stable pool of catalytic biomass in which energy is not diverted towards biomass accumulation, and optimal hydrogen production rates are realised. Here, the application of transparent polyvinyl-alcohol (PVA) cryogel beads to immobilisation of Rhodopseudomonas palustris for long-term hydrogen production is described. PVA cryogel properties are characterised and demonstrated to be well suited to the purpose of continuous photofermentation. Finally, analysis of the long-term biocompatibility of the material is illustrated.ResultsThe addition of glycerol co-solvent induces favourable light transmission properties in normally opaque PVA cryogels, especially well-suited to the near-infrared light requirements of PNSB. Material characterisation showed high mechanical resilience, low resistance to diffusion of substrates and high biocompatibility of the material and immobilisation process. The glycerol co-solvent in transparent cryogels offered additional benefit by reinforcing physical interactions to the extent that only a single freeze–thaw cycle was required to form durable cryogels, extending utility beyond only phototrophic bioprocesses. In contrast, conventional PVA cryogels require multiple cycles which compromise viability of entrapped organisms. Hydrogen production studies of immobilised Rhodopseudomonas palustris in batch photobioreactors showed higher specific hydrogen production rates which continued longer than planktonic cultures. Continuous cultivation yielded hydrogen production for at least 67 days from immobilised bacteria, demonstrating the suitability of PVA cryogel immobilisation for long-term phototrophic bioprocesses. Imaged organisms immobilised in cryogels showed a monolithic structure to PVA cryogels, and demonstrated a living, stable, photofermentative population after long-term immobilisation.ConclusionTransparent PVA cryogels offer ideal properties as an immobilisation matrix for phototrophic bacteria and present a low-cost photobioreactor technology for the further advancement of biohydrogen from waste as a sustainable energy source, as well as development of alternative photo-bioprocesses exploiting the unique capabilities of purple non-sulfur bacteria.

Swelling Resistance and Mechanical Performance of Physical Crosslink‐Based Poly(Vinyl Alcohol) Hydrogel Film with Various Molecular Weight

ABSTRACTThe present work aimed to develop polyvinyl alcohol (PVA) hydrogel films with physically crosslinking through controllable entanglement density of the polymer chains. The viscoelasticity of PVA aqueous solutions was investigated over a broad range in molecular weight. The chain length between the crosslinks in the hydrogel () and entanglement density was determined by the plateau modulus (G'). The value of () increased with the PVA molecular weight, which can be attributed to the enhanced entanglement associated with the hydrogen bonds between inter‐ and interchains. The melting and crystallization of the transparent PVA hydrogel films showed that the crystallinity was below 30%, which indicated that microcrystallites formed. Therefore, the entanglement effect and microcrystallization enhanced the stable crosslinked hydrogel network, which further improved by an increase in the molecular weight. Altogether, the PVA with the molecular weight higher than 88,000 g/mol can be envisioned as a promising material for preparing the hydrogel film possessing excellent performance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1673–1683

Film formation and mechanical properties of an opaque titanium dioxide and transparent polyvinyl alcohol composite films

AbstractMechanical, optical, and film formation properties of titanium dioxide/polyvinyl alcohol (TiO2/PVA) composites were studied. Two identical experimental sets of % TiO2 content were prepared that one set is in the range of 1, 3, 5, 7, 10, 13, and 20 wt% for the film formation and the second set is 5 and 50 wt% for the mechanical measurements. Photon transmission technique (PT) at room temperature was used for the film formation process after annealing for 10 min at the temperatures changing from 100 to 270°C. The increase and decrease in the transmission light intensity (Itr) from the composite films were attributed to void closure and interdiffusion models, respectively. The results were consistent with the data obtained from the film formation processes and mechanical measurements that the addition of TiO2 in PVA had remarkable improvement on mechanical properties, for example, increment in the Young's modulus and the rigidity as TiO2 content increased from 5 to 50 wt%, and it had also good film forming especially above 10 wt% TiO2 for the void closure processes leading to lower the activation energy. It was observed that for the lower content of TiO2 such as 5 wt%, the tensile strength and Young's modulus increased remarkably for heating temperature increased up to 150°C. However, with the increase of TiO2 content, the maximum values of the mechanical strength and modulus were shifted to 180°C for 50 wt% TiO2 from 150°C for 5 wt% TiO2 because of the thermal stability of TiO2.

Biomaterial characteristics and application of silicone rubber and PVA hydrogels mimicked in organ groups for prostate brachytherapy

It is definite that transparent material with similar structural characteristics and mechanical properties to human tissue is favorable for experimental study of prostate brachytherapy. In this paper, a kind of transparent polyvinyl alcohol (PVA) hydrogel and silicone rubber are developed as suitable substitutions for human soft tissue. Segmentation and 3D reconstruction of medical image are performed to manufacture the mould of organ groups through rapid prototyping technology. Micro-structure observation, force test and CCD deformation test have been conducted to investigate the structure and mechanical properties of PVA hydrogel used in organ group mockup. Scanning electron microscope (SEM) image comparison results show that PVA hydrogel consisting of 3g PVA, 17g de-ionized water, 80g dimethyl-sulfoxide (DMSO), 4g NaCl, 1.5g NaOH, 3g epichlorohydrin (ECH) and 7 freeze/thaw cycles reveals similar micro-structure to human prostate tissue. Through the insertion force comparison between organ group mockup and clinical prostate brachytherapy, PVA hydrogel and silicone rubber are found to have the same mechanical properties as prostate tissue and muscle. CCD deformation test results show that insertion force suffers a sharp decrease and a relaxation of tissue deformation appears when needle punctures the capsule of prostate model. The results exhibit that organ group mockup consisting of PVA hydrogel, silicone rubber, membrane and agarose satisfies the needs of prostate brachytherapy simulation in general and can be used to mimic the soft tissues in pelvic structure.

Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea

Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt.

Size dependent optical characterization of semiconductor particle: CdS embedded in polymer matrix

We report the optical investigation and analysis of both nano-sized and micrometer size Cadmium Sulphide particles which is embedded in a transparent polyvinyl alcohol (PVOH) dielectric host material. A designed and fabricated laser based light scattering system using a He-Ne laser of wavelength 632.8nm was used for the measurement and study of the scattering properties of the particles as a function of the scattering angle at this wavelength. An attempt was made to experimentally determine the most significant elements of the Mueller scattering matrix using combinations of randomly and linearly polarized incident laser beam and subsequent analyzers in corresponding orientations. The analysis of the experimental data was done by the method of comparison with theoretically generated data. Novel computational technique, involving single scattering for spherical particles using Mie-theory, was developed and applied. The theoretical data was found to be in good agreement with the experimental data within an acceptable margin of error. The results have proved that the combination of the experimental setup and associated computational method is a highly efficient and reliable in-situ system for monitoring size growth of semiconductor particles in the laboratory.

Size quantification of sub-micron ZnSe semiconductor particles by laboratory scattering methods

A novel route has been developed to synthesize sub-micron Zinc Selenide semiconductor particles through elemental solvothermal process. Transparent polyvinyl alcohol matrix was chosen as host material for embedding these ZnSe particles in order to stop agglomeration of the particles as well as to facilitate optical characterization. Structural and morphological characterizations were carried out through high resolution electron microscopy and UV-vis spectroscopy. In order to understand light scattering phenomena of these particles, they were investigated by a custom made set up which uses a He-Ne laser of wavelength 632.8nm and an array of Silicon photodetectors. An attempt was made to experimentally determine the most significant element of the Mueller scattering matrix. Novel computational technique, involving single scattering for spherical particles using T-matrix theory was applied. The analysis of the experimental data was done by the method of comparison with theoretically generated data. The theoretical prediction was found to agree well qualitatively with the experimental data. Our results validitate that within an acceptable margin of error of the experimental results, the combination of experimental setup and associated computational method is an efficient and reliable in-situ system for size quantification of sub- micron semiconductor particles in the laboratory.

Polydiacetylenevesicles functionalized with N-heterocyclic ligands for metal cation binding

Self assembled poly diacetylene (PDA) based blue vesicles LS-Terpy, LS-DPA, LS-DP and LS-DEA with metal chelating sites have been prepared and characterized. Their response to the presence of metal cations in buffered aqueous solution has been investigated by monitoring changes of colour, UV-Vis absorption and emission. The addition of zinc, manganese, cadmium, mercury or silver salts to solutions of the vesicles induces a colour change from blue to red observable by the naked eye, while the addition of other metal salts, containing ions like Li(+), Na(+), K(+), Mg(2+), Ca(2+), Cr(2+), Ni(2+), Fe(2+), Co(2+), Cu(2+) or Pb(2+), failed to show any changes. The metal ion coordination selectivity of the ligands is slightly different for the vesicle surface immobilized ligands compared to the reported metal cation binding of the corresponding ligands in solution, which may be due to the special environment at the lipid-solution interface. The vesicles aggregate upon metal ion coordination to the embedded ligands as shown by dynamic light scattering (DLS) particle size analysis. The functionalized PDA vesicles retain their response to the presence of aqueous solutions of metal ions if immobilized in transparent polyvinyl alcohol films or on paper.