Enhancement Of Poly Research Articles

Enhancement of Poly(vinyl alcohol) Hydrogel Properties by N-Succinyl Chitosan and Mesona chinensis Extract for Use as Wound Dressings

Hydrogels composed of different ratios of poly(vinyl alcohol), N-succinyl chitosan (NSC), and Mesona chinensis extract, for use as a wound dressing, were synthesized via thermal polymerization. Potassium persulfate was chosen as the initiator and glutaraldehyde as the crosslinking agent. NSC was prepared by modification of chitosan with succinic anhydride. It was found that this preparation method gave a high gel fraction percentage. The structures of the prepared hydrogels were characterized by Fourier-transform infrared spectroscopy, and their morphology by scanning electron microscopy (SEM). In addition, water transport properties, mechanical properties and cytotoxicity were also studied. The SEM results show that the hydrogels exhibited porous structures and that pore size and size distribution increased with increasing NSC content. Hydrogel-water interactions and water transport properties were also studied in terms of swelling ratio, equilibrium water retention, and water vapour transmission rate. These showed an increase, from 637 to 1240 %, 17.8 to 21.4 %, and 110 to 121 g h−1 m−2 respectively with an increase in NSC content. These gels exhibit a lower water vapour transmission rate compared to that of second and third degree burns but higher than normal skin. Similarly, NSC improved the mechanical properties, presented in terms of stress and percentage strain, of the hydrogels. The stress, percentage strain, and Young’s modulus were found to increase from 15 to 32 kPa, 197 to 294 %, and 0.078 to 0.133 kPa respectively. The hydrogels can be considered to be non-toxic based on the in vitro cytotoxicity assay results. In conclusion, the results showed that, by varying composition, hydrogel properties can be tuned to the specific requirements of an ideal wound dressing.

Effect of Nanostructures Addition and Enhancement of Poly (Vinylidene Difluoride) (PVDF) Energy Harvesting

Effect of Nanostructures Addition and Enhancement of Poly (Vinylidene Difluoride) (PVDF) Energy Harvesting

Photorefractive Response Enhancement in Poly(triarylamine)-Based Polymer Composites by a Second Electron Trap Chromophore.

Photorefractive (PR) performances are affected by the components of the photoconductor, sensitizer, nonlinear optical dye, and plasticizer. A photoconductor with high hole mobility promises a faster response time, whereas it induces higher photoconductivity, which leads to easy dielectric breakdown. Adding a second electron trap is effective in controlling photoconductivity. In this study, the role of a second electron trap 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene (TmPyPB) was investigated in a PR composite consisting of a photoconductor of poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] with a high hole mobility, a nonlinear optical chromophore of piperidinodicyanostyrene, a plasticizer of (2,4,6-trimethylphenyl)diphenylamine, and a sensitizer of [6,6]-phenyl C61 butyric acid-methyl ester. The minimum time response with the maximum optical diffraction efficiency and sensitivity was measured at a 1 wt % content of TmPyPB. These results were consistent with the number of charge carriers trapped per unit volume and per unit time Nc (cm–3 s–1), which is defined as the ratio between the initial trap density Ti (cm–3) and response time τ (s), at a 1 wt % content of TmPyPB. A faster response time of 149 μs, optical diffraction of 24.1% (external diffraction of 4.8%), and a sensitivity of 2746 cm2 J–1 were measured at 50 V μm–1 for the sample with 1 wt % TmPyPB. High loading of 5 wt % TmPyPB led to a large decrease in photoconductivity and effectively suppressed the dielectric breakdown under a stronger electric field, whereas a slower response time with lower diffraction efficiency was observed for optical diffraction.

Electroactive phase enhancement in poly(vinylidene fluoride‐hexafluoropropylene)/polycarbonate blends by hybrid nanofillers

AbstractElectroactive β phase content of poly(vinylidene fluoride‐hexafluoropropylene) (PHP) was enhanced by blending approach with polycarbonate (PC) combined with application of barium titanate–multi‐walled carbon nanotubes (BT–MWCNT) hybrid nanofillers to boost the dielectric performance of PHP. The samples were melt‐blended at 90/10 and 70/30 wt% (PHP/PC) in the presence of BT and/or MWCNT. Scanning electron microscopic (SEM) results indicated compatibilization of the structure by adding BT or MWCNT; however, the best refinement in morphology was obtained in (90/10)/1.5/1.5 (PHP/PC)/BT/MWCNT nanocomposite. Transmission electron microscopy (TEM) micrographs illustrated the selective localization of BT at PHP and MWCNT at PC while some of both nanofillers were found at the interphase. Fourier transform infrared spectroscopy and X‐ray diffraction analysis results depicted the increase in β/α ratio of the nanocomposites with a synergistic effect in (90/10)/1.5/1.5 nanocomposite, attributed to the combined utilization of BT and MWCNT and their selective localization in the PHP/PC immiscible blends. Differential scanning calorimetry analysis substantiated the nucleating effects of BT and MWCNT and consistency with SEM and TEM observations in nanofillers selective localization. The findings of this work suggest that simultaneous introduction of ceramic and conductive nanofillers with their selective localization in PHP/PC blends is efficacious in improving electroactive phase of composites at low filler content.

Eliminating the Detrimental Effect of Secondary Doping on PEDOT : PSS Hole Transporting Material Performance.

Secondary doping has a long history of use in conductivity enhancement in poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS). However, very little research has addressed its detrimental effect on application performance of PEDOT : PSS in organic solar cells. Herein, it was shown that the uneven drying of secondary dopant-water mixture results in a nonuniform/continuous film structure, causing severe damage to the device efficiencies (dropping about 8 and 23 % for poly[(2,6-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)-benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))] (PBDB-T) : 3,9-bis(2-methylene-(3-(1,1-dicyanomethylene)-indanone))-5,5,11,11-tetrakis(4-hexylphenyl)-dithieno[2,3-d:2',3'-d']-s-indaceno[1,2-b:5,6-b']dithiophene (ITIC) and poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithio-phene))-co-(1,3-di(5-thiophene-2-yl)-5,7-bis(2-ethylhexyl)-benzo[1,2-c:4,5-c']dithiophene-4,8-dione))](PM6) : (3,9-bis(1-oxo-2-methylene-3-(1,1-dicyanomethylene)-5,6-difluoroindanone)-5,5,11,11-tetrakis(4-n-hexylphenyl)-dithieno[2,3d:2',3'd']-s-indaceno[1,2b:5,6b']dithiophene (IT-4F) cells, respectively) and thermal stabilities. Moreover, a simple yet robust dialysis treatment was proposed to solve the issue of noncontinuity and retain the secondary doping's advantages of quinoid structure simultaneously, thus demonstrating a significant enhancement in device performance. This study will be of great importance to the future exploration of the next generation of post-treatment strategy.

Efficiency enhancement in polymer solar cells using combined plasmonic effects of multi-positional silver nanostructures

Abstract Achieving high absorption enhancement in a broad wavelength range without increasing the thickness of active layer is essential for improving the performance of polymer solar cells. In this work, we report efficiency enhancement in poly({4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno [3,4-b]thiophenediyl}): [6,6]-phenyl C71-butyric acid methyl ester active layer based polymer solar cells by incorporating silver nanostructures simultaneously in cathode buffer layer and active layer. Efficiency of the device was increased from 6.53% to 7.53% after incorporating the nanostructures. The plasmonic devices exhibited superior performance in a broad wavelength range from 450 nm to 750 nm. Photoluminescence measurements were carried out to confirm the improvement in light harvesting capability of the devices. Finite-difference time-domain simulations and Raman spectroscopy were employed to verify the electric field intensity enhancement around the nanostructures. The performance enhancement mechanism was realized based on theoretical simulations and optical measurements.

Polyaniline (PANI) mediated cation trapping effect on ionic conductivity enhancement in poly(ethylene oxide) based solid polymer electrolytes with application in solid state dye sensitized solar cells

The ionic conductivity enhancement in solid polymer electrolytes due to introduction of polyaniline (PANI) conducting polymer is demonstrated using poly(ethylene oxide) (PEO) based solid polymer electrolyte comprising tertapropylamonium iodide (Pr4NI) and iodine (I2). The electrolyte with optimized composition has been characterized by ionic conductivity measurements, DC polarization test, Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Differential Scanning Calorimetry (DSC). About eight-fold increase in the ionic conductivity from 9.33 × 10−6 Scm−1 to 8.61 × 10−5 Scm−1 at room temperature was obtained by the addition of 1.5 wt% of PANI to the PEO solid polymer host. FTIR measurements suggest that Pr4N+ cations are able to coordinate not only with oxygen atoms of PEO, but also with nitrogen atoms of the PANI polymer effectively immobilizing or “trapping” the bulky Pr4N+ cations and promoting ionic dissociation. DSC studies show that PANI, also acting as a plasticizer, reduces the crystallinity of PEO and lower it's melting temperature. The DC polarization tests confirmed the increased iodide ion conductivity evidently mediated by PANI due to the combined effect of cation trapping and plasticizing. Solid state dye sensitized solar cells fabricated with optimized electrolyte composition incorporating PANI exhibited the highest energy conversion efficiency of 5.01% compared to 3.52% for the DSSC without PANI.

β‐Polymorph enhancement in poly(vinylidene fluoride) by blending with polyamide 6 and barium titanate nanoparticles

AbstractPolyamide 6 (PA6) as a cost‐effective polar polymer and barium titanate (BT) as piezoelectric ceramic nanofiller were melt compounded with poly(vinylidene fluoride) (PVDF) matrix to enhance the β electroactive phase. A series of samples with two blending ratios of PVDF/PA6 (90/10 and 70/30 [wt%/wt%]) each containing 1, 3, and 5 wt% of BT were prepared. The SEM results revealed that the addition of BT to the neat blends refined the biphasic morphology which is mainly due to selective localization of BTs in PA6 dispersed phase as confirmed by TEM observation and wetting parameter predictions. The EDX analysis demonstrated a uniform distribution of BT nanoparticles in the filled systems. FTIR and XRD results showed that β content increased as a result of blending while the α phase was suppressed. The BT nanoparticles inclusion to the blends showed a synergistic effect on the β‐polymorph content. These results in combination with the data derived from DSC (indicating reduction of the total crystallinity) complement the idea of β enhancement by the addition of BT nanoparticles and PA6 into PVDF.

Tuning the sensitivity of fluoroionophore-based K+ sensors via variation of polymer matrix: A comparative study

Optical sensors were prepared via immobilization of K+ fluoroionophore (K+FI) into different hydrophilic polymers and their properties (luminescence brightness, stability, sensitivity, cross talk to sodium, dynamic range, response time) were investigated. Depending on the character of the used polymeric matrix, the fluorescence quantum yields for the K+-fluoroionophore complex (500 mM K+) span from 44 % in commercial polyurethane hydrogel D1 to 18 % in poly(2-hydroxyethyl methacrylate). Dynamic intensity measurements show reversibility of the sensors and response times (t90) below 1 min for most of the materials. Blending of poly(2-hydroxyethyl methacrylate) with polyurethane hydrogels is necessary to ensure compatibility of the indicator and the matrix. Comparison of dissociation constants (Kd) reveals moderate sensitivity enhancement in more hydrophilic polyurethane hydrogel D1 (Kd 51.8 mM) and much stronger enhancement in poly(2-hydroxyethyl methacrylate) (Kd 15.4 mM) compared to previously used hydrogel D4 (Kd 60.4 mM). Drastic increase in the sensitivity upon addition of negatively-charged aliphatic sulfonates is observed (Kd < 3 mM). In case of the latter, the enhancement in the sensitivity is significantly lower in presence of sodium ions. Modification of a commercially available polyurethane hydrogel with sulfonate groups enables preparation of stable sensors with improved binding ability (Kd 11.1 mM). This study demonstrates the fundamental role of the polymer matrix in characteristics of the solid-state optical potassium sensors and provides the guidelines for general design of ion sensors with improved characteristics.

Enhancement of poly(vinyl alcohol) using delaminated layered double hydroxide for the formulation of mechanically strong nanocomposite hydrogel

ABSTRACTIn this work, a new type of nanocomposite hydrogel (NCH) has been prepared by crosslinking poly(vinyl alcohol) (PVA) with delaminated layered double hydroxides (LDHs). The LDH was first intercalated with sodium dodecyl sulfate to facilitate delamination. The intercalated LDH was synthesized via coprecipitation followed by subsequent hydrothermal treatment and delamination in dimethyl sulfoxide. The mechanical properties of PVA–NCH with 0.1 wt % LDH were significantly enhanced. The tensile strength of PVA–NCH containing 0.1 wt % LDH was remarkably increased by threefold, while the value of Young's modulus was recorded to be the highest compared to other ratios. The morphologies and microstructures of the PVA–NCH were further investigated by scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared, and X‐ray diffraction. TEM image showed the LDH was delaminated into single nanosheets. It was demonstrated that the delaminated LDH played an important role in increasing physical crosslinking with PVA macromolecules to form strong hydrogel through hydrogen bonding network.RESEARCH HIGHLIGHTS A fast and simple intercalation process of layered double hydroxides (LDHs) with dimethyl sulfoxide to delaminate the organically modified LDH at room temperature. Delaminated Mg2Al–LDH was used as a nanocrosslinker to produce mechanically strong poly(vinyl alcohol) nanocomposite hydrogel. Enhanced mechanical properties in terms of tensile strength and modulus of elasticity (Young's modulus) were observed with the addition of 0.1% sodium dodecyl sulfate–LDH. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48637.

Enhancement of Poly(vinyl chloride) Electrolyte Membrane by Its Exposure to an Atmospheric Dielectric Barrier Discharge Followed by Grafting with Polyacrylic Acid

A poly(vinyl chloride) (PVC) membrane was exposed to atmospheric-pressure dielectric barrier discharge and subsequently wet-chemically grafted with poly(acrylic acid) (PAA) and then consumed with poly(ethyleneimine) (PEI). The thus modified membrane was characterized by measurement of the static water contact angle, by scanning electron microscopy, infrared spectroscopy (ATR-FTIR), thermogravimetry (TGA) and electrolytic responses. The TGA favors a thermally stable grafted PVC membrane. The ATR-FTIR revealed the existence of an ultra-thin PAA layer grafted onto the surface of the plasma-modified PVC membrane. The ion exchange capacity measurement of the grafted poly(vinyl chloride) (PVC–PAA) sample was close to that of additionally wet-chemically aminated with PEI for 12 h or more (PVC–PAA–PEI). It means that PVC–PAA membranes do not need necessarily further modifications. As concomitant helpful effect, it was observed that the swelling degree of the PVC membrane was reduced after plasma exposure due to plasma-induced crosslinking.

Plasmonic effects of Ag nanoparticles for absorption enhancement in polymer solar cells with MoO3 passivation layer

In this work, we numerically demonstrate absorption enhancement in poly (3-hexylthiophene-2,5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly ({4,8-bis [(2-ethylhexyl)oxy]benzo [1,2-b:4,5-b′]dithiophene-2,6-diyl}{3-fluoro-2-[(2-ethylhexyl)-carbonyl]-thieno-[3,4-b]thiophenediyl}) (PTB7):[6,6]-phenyl-C71-butyric acid methyl ester (PC70BM) based polymer solar cells (PSCs) by utilizing plasmonic effects of Ag nanoparticles (Ag NPs) incorporated at the interface between indium-tin-oxide (ITO) anode and an ultra-thin MoO3 anode buffer layer. The influence of factors such as particle size, spacing between neighboring particles, thickness of the active layer and the thickness of the MoO3 layer on the optical absorption enhancement has been investigated. Including 75 nm sized Ag NPs at the interface between ITO and 1 nm thick MoO3 layer resulted in 18.6% and 22.6% absorption enhancement in 80 nm thick P3HT:PCBM and PTB7:PC70BM active layers, respectively. PSCs have been fabricated using PTB7:PCBM as the active layer and 75 nm sized Ag NPs as the absorption enhancers for demonstrating performance enhancement. An improvement in device efficiency from 5.44% to 6.74% has been achieved by optimizing the number density of Ag NPs. Present study reveals that incorporating Ag NPs at the ITO/MoO3 interface is an effective approach to eliminate exciton quenching and charge carrier recombination problems while retaining most of the absorption enhancement induced by the Ag NPs.

Synergistic effects of polyethylene glycol and organic montmorillonite on the plasticization and enhancement of poly(lactic acid)

ABSTRACTPoly(lactic acid) (PLA)/polyethylene glycol (PEG)/organic montmorillonite (OMMT) composites were prepared by melt blending, and their mechanical, rheological behavior, crystalline behavior, and thermal stability were investigated. Results showed that the elongation‐at‐break and notch‐impact strength of PLA/15PEG/1.5OMMT were 466.45% and 4.34 kJ m−2, respectively, which were nearly 42 and 2 times higher than those of PLA, respectively. The elongation‐at‐break of PLA/15PEG/1.5OMMT was also 33 times higher than that of PLA/15PEG and 30 times that of PLA/1.5OMMT. With addition of PEG, PLA chains could insert to OMMT effectively and increase the layer space of OMMT. The characteristics of dynamic behavior and fracture morphology showed that the plasticizer PEG could soften the PLA matrix, leading to easy plastic deformation. OMMT was well distributed in the PLA matrix and able to transfer the stress of external forces, thereby contributing to the matrix yielding initiation and expansion of polymer composites. The synergistic effect of OMMT and PEG was determined by studying the mechanical properties of PLA/PEG/OMMT composite. Differential scanning calorimetry and thermogravimetry studies revealed that OMMT as a nucleating agent improved crystallization and thermal stability. Thus, the synergistic effect of OMMT and PEG balanced the stiffness and toughness of PLA. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47576.

Non-additive separation selectivity enhancement in poly(4-methyl-2-pentyne) in relation to C1-C4-alkanes

This study examines the fundamental and practical aspects of C1-C4 hydrocarbons separation (pure or in binary or ternary mixtures), using highly permeable glassy 1,2-disubstituted polyacetylenes. Poly(4-methyl-2-pentyne) (PMP) was chosen as the main object of study. An attempt is made here to carry out a systematic comparative study of the PMP permeability target parameters using correlation detection and a thermodynamic gas/polymer model. A non-isothermal application method was used, which allowed us to work with each gas individually and with various mixtures to obtain an experimental value for the dependence on temperature of the permeability of C1, C3, C4 hydrocarbons. This is the first time that this method has been used for the study of glassy polymers with high free volume. An interesting phenomenon of an increase in non-additive separation selectivity α was shown (for a value of α of between ∼10 and ∼8000 units) with increase of butane activity (p/psat) from 0.02 to 0.94 in the feed gas mixture. In the current study, an explanation is given for the increase in non-additive selectivity for PMP membrane separation. Modelling was carried out of the separation process of a binary butane/methane mixture using this non-additive phenomenon, which gives rise to concentrated components.

Staphylococcus aureus lipoproteins augment inflammatory responses in poly I:C-primed macrophages

Secondary bacterial infection contributes to severe inflammation following viral infection. Among foodborne pathogenic bacteria, Staphylococcus aureus is known to exacerbate severe inflammatory responses after infection with single-stranded RNA viruses such as influenza viruses. However, it has not been determined if S. aureus infection enhances inflammatory responses after infection with RNA enteric viruses, including rotavirus, which is a double-stranded RNA virus. We therefore investigated the molecular mechanisms by which a cell wall component of S. aureus enhanced inflammatory responses during enteric viral infection using poly I:C-primed macrophages, which is a well-established model for double-stranded RNA virus infection. S. aureus lipoproteins enhanced IL-6 as well as TNF-α production in poly I:C-primed macrophages. Pam2CSK4, a mimic of Gram-positive bacterial lipoproteins and S. aureus lipoproteins, also significantly enhanced IL-6 production in poly I:C-primed macrophages. While IFN-β expression was increased in poly I:C-primed macrophages treated with Pam2CSK4 or S. aureus lipoproteins, the level of IL-6 enhancement in poly I:C-primed macrophages was decreased in the presence of anti-IFN-α/β receptor antibody, suggesting that IFN-β plays an important role in enhanced IL-6 production. Phosphatidylinositol-3-kinase, Akt, ERK and NF-κB were also involved in the enhanced IL-6 production. Collectively, these results suggest that S. aureus lipoproteins induce excessive inflammatory responses in the presence of poly I:C.

A comparative study on the morphology of P3HT:PCBM solar cells with the addition of Fe3O4 nanoparticles by spin and rod coating methods

Our previous study presented up to 20% power conversion efficiency (PCE) enhancement of poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester (P3HT:PCBM) solar cells under the Fe3O4 nanoparticles (NPs) self-assembly (SA) effect by spin coating. Fe3O4 NPs (about 11 nm hydrodynamic diameter) form a thin layer at the top interface of the light absorbing active layer, which results in the generation of PCBM rich region improving the charge transport (Zhang et al. Sol Energ Mat Sol C 160:126–133, 2017). In order to investigate the feasibility of this Fe3O4 NPs SA effect under large-scale production condition, a smooth rod was implemented to mimic roll-to-roll coating technique and yield active layers having about the same thickness as the spin-coated ones. Small angle neutron scattering and grazing incidence X-ray diffraction were employed finding out similar morphologies of the active layers by these two coating techniques. However, rod-coated solar cell’s PCE decreases with the addition of Fe3O4 NPs compared with the one without them. This is because PCBM rich region is not created at the top interface of the active layer due to the absence of Fe3O4 NPs, which is attributed to the weak convective flow and low diffusion rate. Moreover, in the rod-coated solar cells, the presence of Fe3O4 NPs causes decrease in P3HT crystallinity, thus the charge transport and the device performance. Our study confirms the role of spin coating in the Fe3O4 NPs SA effect and enables researchers to explore this finding in other polymer nanocomposite systems.

Enhancement of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) accumulation in Arxula adeninivorans by stabilization of production

BackgroundIn recent years the production of biobased biodegradable plastics has been of interest of researchers partly due to the accumulation of non-biodegradable plastics in the environment and to the opportunity for new applications. Commonly investigated are the polyhydroxyalkanoates (PHAs) poly(hydroxybutyrate) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHB-V). The latter has the advantage of being tougher and less brittle. The production of these polymers in bacteria is well established but production in yeast may have some advantages, e.g. the ability to use a broad spectrum of industrial by-products as a carbon sources.ResultsIn this study we increased the synthesis of PHB-V in the non-conventional yeast Arxula adeninivorans by stabilization of polymer accumulation via genetic modification and optimization of culture conditions. An A. adeninivorans strain with overexpressed PHA pathway genes for β-ketothiolase, acetoacetyl-CoA reductase, PHAs synthase and the phasin gene was able to accumulate an unexpectedly high level of polymer. It was found that an optimized strain cultivated in a shaking incubator is able to produce up to 52.1% of the DCW of PHB-V (10.8 g L−1) with 12.3%mol of PHV fraction. Although further optimization of cultivation conditions in a fed-batch bioreactor led to lower polymer content (15.3% of the DCW of PHB-V), the PHV fraction and total polymer level increased to 23.1%mol and 11.6 g L−1 respectively. Additionally, analysis of the product revealed that the polymer has a very low average molecular mass and unexpected melting and glass transition temperatures.ConclusionsThis study indicates a potential of use for the non-conventional yeast, A. adeninivorans, as an efficient producer of polyhydroxyalkanoates.

Enhancement of poly(L-lactide)-degrading enzyme production by Laceyella sacchari LP175 using agricultural crops as substrates and its degradation of poly(L-lactide) polymer

Optimization of the medium for poly(L-lactide) (PLLA)-degrading enzyme production in shake flask experiments was investigated using agricultural products as substrates. Cassava chips and soybean meal were the best carbon and nitrogen sources, respectively, as determined by the one-factor-at-a-time method. Enzyme production was significantly enhanced by the addition of phosphates, but was suppressed by the addition of ammonium salt. The maximum enzyme production, 65.5 U/mL, was obtained from the optimized medium consisting of 4.64 g/L cassava chips, 1.53 g/L soybean meal and 0.31 g/L PLLA powder using central composite design in the basal medium. The optimal physical factors in 3 L airlift fermenter were 50 °C, pH 7.0 and 0.5 vvm aeration rate for 18 h, yielded 94.4 U/mL. The crude enzyme was shown to be able to hydrolyze PLLA powder (91%) at 50 °C in 72 h which showed high efficiency for recycling of PLLA polymer and reducing the global environmental problem.

Enhancement in Organic Photovoltaics Controlled by the Interplay between Charge-Transfer Excitons and Surface Plasmons.

In this work, we investigate plasmonic enhancement in poly(3-hexylthiophene):phenyl-C61-butyric acid methyl ester organic photovoltaics (OPVs) by integrating shape- and size-controlled bimetallic gold core–silver shell nanocrystals (Au–Ag NCs) into the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate hole-transport layer. We observed that the best-performing Au–Ag NC-incorporated OPVs improved the power conversion efficiency by 9% via a broadband increase in photocurrent throughout the visible spectrum. Our experimental and computational results suggest that the observed photocurrent enhancement in plasmonic OPVs originates from both enhanced absorption and improved exciton dissociation and charge collection. This is particularly achieved by placing metal NCs near the interface of the active layer and hole-transport layer. The impedance spectroscopy results suggest that Au–Ag NCs reduce recombination and also increase the internal exciton to carrier efficiency by driving the dissociation of bound charge-transfer states to free carriers.

Effective Exfoliation of Expanded Graphite in Rigid Poly(methyl methacrylate) and Its Dispersion and Enhancement in Poly(vinylidene fluoride)

Effective Exfoliation of Expanded Graphite in Rigid Poly(methyl methacrylate) and Its Dispersion and Enhancement in Poly(vinylidene fluoride)