Low Molar Mass Research Articles

Fungal Treatment for the Valorization of Technical Soda Lignin

Technical lignins produced as a by-product in biorefinery processes represent a potential source of renewable carbon. In consideration of the possibilities of the industrial transformation of this substrate into various valuable bio-based molecules, the biological deconstruction of a technical soda lignin by filamentous fungi was investigated. The ability of three basidiomycetes (Polyporus brumalis, Pycnoporus sanguineus and Leiotrametes menziesii) to modify this material, the resultant structural and chemical changes, and the secreted proteins during growth on this substrate were investigated. The three fungi could grow on the technical lignin alone, and the growth rate increased when the media were supplemented with glucose or maltose. The proteomic analysis of the culture supernatants after three days of growth revealed the secretion of numerous Carbohydrate-Active Enzymes (CAZymes). The secretomic profiles varied widely between the strains and the presence of technical lignin alone triggered the early secretion of many lignin-acting oxidoreductases. The secretomes were notably rich in glycoside hydrolases and H2O2-producing auxiliary activity enzymes with copper radical oxidases being induced on lignin for all strains. The lignin treatment by fungi modified both the soluble and insoluble lignin fractions. A significant decrease in the amount of soluble higher molar mass compounds was observed in the case of P. sanguineus. This strain was also responsible for the modification of the lower molar mass compounds of the lignin insoluble fraction and a 40% decrease in the thioacidolysis yield. The similarity in the activities of P. sanguineus and P. brumalis in modifying the functional groups of the technical lignin were observed, the results suggest that the lignin has undergone structural changes, or at least changes in its composition, and pave the route for the utilization of filamentous fungi to functionalize technical lignins and produce the enzymes of interest for biorefinery applications.

Morphological selectivity of the films of linear and star-shaped poly (ε-caprolactone)

Films created by poly (e-caprolactone) (PCL) have made a lot of consideration in biomedical applications because of their biodegradability, biocompatibility, incredible flexibility, and nontoxic degradation by-products. In this study, switching behavior of surface morphology of linear and star-shaped PCL as a function of polarity of the substrate, molecular weight of the polymer, solvent vapor annealing, solvent annealing, and thermal annealing were investigated. Films of PCL were prepared by drop casting method and their morphology was visualized through atomic force microscopy (AFM). Although, the whole study is based on AFM imaging, some of the basic morphologies of PCL films as obtained by AFM are also compared with SEM and TEM analysis. The substantial difference in polarity and roughness of mica and silicon wafers leads to different chain orientation of the polymer chains. Morphology transition strongly depends on the molecular weight of the polymer, low molar mass PCL presented larger surface domains compared to their higher molar mass analogs. Annealing of polymer with THF and ethanol vapors has improved the long-range ordering of PCL chains, while hexane and water vapors led to swelling of the films. The morphology of the film has also shown selectivity for the casting solvent. Thermal annealing around the melting temperature of the PCL made polymeric chains more extended and uniformly oriented.

Off-line analysis in the manganese catalysed epoxidation of ethylene-propylene-diene rubber (EPDM) with hydrogen peroxide.

The epoxidation of ethylene-propylene-diene rubber (EPDM) with 5-ethylidene-2-norbornene (ENB) as the diene to epoxidized EPDM (eEPDM) creates additional routes to cross-linking and reactive blending, as well as increasing the polarity and thereby the adhesion to polar materials, e.g., mineral fillers such as silica. The low solubility of apolar, high molecular weight polymers in the polar solvents constrains the catalytic method for epoxidation that can be applied. Here we have applied an in situ prepared catalyst comprising a manganese(ii) salt, sodium picolinate and a ketone to the epoxidation of EPDM rubber with hydrogen peroxide (H2O2) as the oxidant in a solvent mixture, that balances the need for polymer and catalyst/oxidant miscibility and solubility. Specifically, a mixture of cyclohexane and cyclohexanone is used, where cyclohexanone functions as a co-solvent as well as the ketone reagent. Reaction progress was monitored off-line through a combination of Raman and ATR-FTIR spectroscopies, which revealed that the reaction profile and the dependence on the composition of the catalyst are similar to those observed with low molar mass alkene substrates, under similar reaction conditions. The combination of spectroscopies offers a reliable method for off-line reaction monitoring of both the extent of the conversion of unsaturation (Raman) and the extent of epoxidation (FTIR) as well as determining side reactions, such as epoxide ring opening and further, aerobic oxidation. The epoxidation of EPDM described, in contrast to currently available methods, uses a non-scarce manganese catalyst and H2O2, and avoids side reactions, such as those that can occur with peracids.

Kinetics of MMA Atom Transfer Radical Polymerization Initiated by Reducing Agent in Stirred Batch Emulsion Reactor

AbstractAb initio emulsion atom transfer radical polymerization (ATRP) differs from regular emulsion polymerization because the kinetic and thermodynamic aspects of each process are very unlikely alike. This paper presents a kinetic analysis of activator generated by electron transfer (AGET) ATRP of methyl methacrylate (MMA) in a stirred emulsion reactor. The focus of the study is to assess the variation of the monomer content in the organic phase and the rate polymerization for different reaction temperatures, as well as the impact of surfactant content and stirring speed on latex stability. Poly(methyl methacrylate) (PMMA) polymer samples are analyzed by means of gravimetry, dynamic light scattering, gel permeation chromatography, and HNMR techniques to determine monomer conversion, polymer particle diameter, molecular weight distribution, and polymer molecular structure, respectively. The results show the production of PMMA of narrow polydispersity index (Ð) and low molar mass (Mn) for MMA conversion around 60% and detect two‐regions instead of a three‐regions trend of rate of polymerization (Rp) as conventional emulsion polymerization. The reaction rate increases during the nucleation stage and then flattens over an invariant trend which confirms a living feature of the AGET ATRP polymerization. The average number of radicals per latex particle (ñ) is also debated.

New structure host material for phosphorescent OLED devices

New carbazole and quinoxaline based low molar mass bipolar derivative was synthesized, characterized, and tested as host derivative in phosphorescent organic light emitting diodes (OLEDs). The material could form homogeneous amorphous materials (layers) with very high glass transition temperature of 136 °C and also with very high initial thermal decomposition temperature of about 387 °C. The electron photoemission spectra of the layers of the synthesized compound showed ionization potentials of about 5.85 eV. The compound was tested as host material for green Ir(ppy)3 , blue FIrpic, and yellow PO-01 triplet phosphorescent guests. The device with the yellow PO-01 triplet emitter exhibited the best overall performance. The most efficient yellow OLED demonstrated turn-on voltage of 4.9 V, a maximum brightness exceeding 4050 cd/m2 and current efficiency of 10.8 cd/A with power efficiency of 6.9 lm/W at 100 cd/m2.

The Effect of the HLB Value of Sucrose Ester on Physiochemical Properties of Bigel Systems

The current research explored the effect of different sucrose esters (SEs), with different hydrophilic–lipophilic balance (HLB) values, on bigel structure and properties. Bigels consisting of a water phase with glycerol and gelatin and an oil phase with glycerol mono-stearate, lecithin, and SEs with different HLB values were prepared. Rheological and thermal analyses revealed similar gelation-melting transitions governed by glycerol-monostearate crystallization (at ≈55 °C) for all bigel samples. The bigel matrix of the H1 and H2 samples (bigels consisting of SEs with HLBs of 1 and 2, respectively) demonstrated physical gel rheological characteristics of higher elastic and solid-like behavior compared with the H6 sample (bigel consisting SE with HLB 6). A similar trend was observed in the mechanical analysis with respect to hardness, firmness, and spreadability values, which were in the order of H1 > H2 > H6. This behavior was attributed to droplet size observed in the microscopy analysis, revealing significantly smaller droplets in the H1 and H2 samples compared with the H6 sample. These differences in droplet size were attributed to the diffusion kinetics of the low-molecular-weight surfactants. More specifically, the ability of mono-esterified SEs to diffuse faster than fully esterified SEs due to lower molar mass leads to a higher SE content at the oil-in-water (O/W) interface as opposed to the bulk oil phase. The results demonstrate the importance of the interface content in O/W bigel systems, providing an effective way to alter and control the bigel bulk properties.

Influence of the PVOH molar mass on the morphology and functional properties of EVOH/PVOH films prepared by melt blending

AbstractThe influences of the molar mass (low, medium, and high) and content of poly(vinyl alcohol) (PVOH) dispersed by melt‐blending in an ethylene vinyl alcohol (EVOH) copolymer on the morphology, microstructure, thermal, mechanical, and oxygen barrier properties were investigated. Multilayer films with external low‐density polyethylene layers and inner EVOH/PVOH blend layer and respective monolayer films were elaborated and characterized. EVOH/PVOH blends exhibited a good compatibility because of the initial presence of PVOH segments in EVOH. The detailed quantitative analysis of the morphology performed for all blends showed that the finest dispersion was obtained with the PVOH with the lowest molar mass. The properties of the films as a function of the PVOH content and its molar mass were determined herein. Significant improvement of barrier properties was obtained at moderated water activities (up to aw = 0.6) by using the PVOH with the lowest molar mass. Compared to the neat EVOH material, the oxygen permeability coefficients decreased by a factor 2 by adding 15 vol% PVOH while the thermal and mechanical properties remained similar.

Progress in the Free and Controlled Radical Homo- and Co-Polymerization of Itaconic Acid Derivatives: Toward Functional Polymers with Controlled Molar Mass Distribution and Architecture.

Polymeric derivatives of itaconic acid are becoming increasingly more interesting for research and industry because itaconic acid is accessible from renewable resources. In spite of the structural similarity of poly(itaconic acid derivatives) to poly(methacrylates), they are much less reactive, homopolymerize only sluggishly by free radical polymerization (FRP), and are often obtained with low molar masses and conversions. This has so far limited their use. The reasons for the low reactivity of itaconic acid derivatives (including itaconimides, diitaconates, and diitaconamides) are combined steric and electronic effects, as demonstrated by the body of literature on the FRP homopolymerization kinetics of these monomers which is summarized herein. These problems can be solved to a large extent by using controlled radical polymerization (CRP) techniques, notably atom transfer radical polymerization (ATRP) and reversible addition and fragmentation chain transfer radical polymerization (RAFT). By optimizing the reaction conditions for the ATRP and RAFT of itaconic acid derivatives, in particular the reaction temperature, linear relations between molar mass and conversion are obtained in many cases, and homopolymers with high molar masses and reasonably narrow polydispersity indices become accessible. This review presents the state-of-the-art FRP and CRP of itaconic acid derivatives, and highlights functional polymers obtained by these methods.

Evaluation of polymer/bentonite synergy on the properties of aqueous drilling fluids for high-temperature and high-pressure oil wells

The increasing demand for energy sources has led to oil field exploration under inhospitable conditions, where non-aqueous drilling fluids are commonly used due their physical and chemical stability. However, they exhibit a number of environmental constraints and the cuttings produced require expensive treatments before disposal. Aqueous drilling fluids are currently less thermally resistant and generally entail the use of chromium lignosulfonate as clay dispersant, which provides stability to rheological properties and filtration control under high temperature and high pressure (HTHP). This study elucidates the role played by synergic effect of a novel eco-friendly high-performance water-based drilling fluid using bentonite and vinyl polymers (polyvinylpyrrolidone (PVP) and partially hydrolyzed polyacrylamide (PHPA)) as the main constituents. Filtration and rheological properties of the drilling fluids were determined on a HTHP filtration system and on a rotational viscometer, respectively. Systems using high molar mass PVP (HMM PVP) showed higher values for viscosity, gel strength and yield stress, due to promotion of flocculation. On the other hand, dispersed systems were obtained using low molar mass PVP (LMM PVP), through ion-dipole interactions between PVP and clay particles. Dispersed systems provided stable rheological parameters over the entire range of temperature and pressure studied (up to around 120 °C and 3450 kPa). Linear clay swelling tests showed that LMM PVP and water had similar profiles, promoting clay dispersion. Profitable low filtrate volumes (12 mL) were obtained for PVP-based drilling fluids in conditions where non-aqueous fluids are currently applied.

PURIFICACIÓN Y CARACTERIZACIÓN DE INHIBIDORES DE PAPAÍNA PROVENIENTES DE SEMILLAS DE AMARANTO (Amaranthus caudatus) Y FRIJOL (Phaseolus vulgaris)

Los inhibidores de proteasas vegetales con frecuencia son proteínas de baja masa molar, presentes en tejidos de almacenamiento y aéreos de las plantas. Su expresión se induce en respuesta al daño por insectos y microorganismos patógenos y el contenido de estos inhibidores puede ser alto en órganos de cereales y leguminosas. Bajo la premisa de que la combinación de técnicas de purificación de proteínas de baja y alta resolución permite incrementar la actividad específica de inhibidores de proteasas presentes en tejidos vegetales, el objetivo de este estudio fue aislar, purificar y caracterizar bioquímicamente inhibidores de papaína a partir de semillas de amaranto (Amaranthus caudatus) y frijol (Phaseolus vulgaris). El diseño experimental fue completamente al azar para seleccionar las técnicas de baja resolución que incrementan significativamente (p≤0.05) el grado de purificación de los extractos tratados. En todos los estudios se hicieron tres repeticiones y las mediciones se realizaron por triplicado. A partir de harinas de semillas de amaranto y frijol se obtuvieron extractos proteicos crudos que después se ultrafiltraron en membranas de 10 kDa. Las fracciones de baja masa molar se purificaron por cromatografía de afinidad en papaína-glioxil-sepharosa 6B-CL. El extracto crudo de amaranto presentó actividad inhibidora de 1.177 ± 0.067 mU·mL-1 y el de frijol 1.556 ± 0.542 mU·mL-1. Los extractos con purificación parcial de amaranto y frijol se purificaron por cromatografía de afinidad en papaína-glioxil-sepharosa 6B-CL, hasta 137.5 y 79.1 veces, respectivamente. La masa molar estimada fue 7.50 kDa para el inhibidor de amaranto y 8.20 kDa para el de frijol. El inhibidor de amaranto mostró inhibición competitiva con Ki de 0.872 µM, mientras que la del frijol fue no competitiva y con Ki de 0.058 µM. Esto evidencia la presencia de inhibidores de cisteíno proteasas en las semillas de amaranto y frijol.

Preparation of stiffer ternary blends of polypropylene/polyamide 6/biodegradable polymers with improved interfacial adhesion

AbstractBlends of polypropylene (PP), polyamide 6 (PA6), and biodegradable polymers (BPs) such as poly(D,L‐lactic acid) (PDLLA), poly(lactic acid‐co‐ε‐caprolactone) (poly[LA‐co‐ε‐CL]) and poly(ε‐caprolactone) (PCL) were prepared using a twin‐screw mini‐extruder. The composition of the blend PP/PA6 was fixed at a mass proportion of 70/30, and the compatibilized blends contain 5 wt% of each BP. The morphology observed through scanning electronic microscopy, the dynamic mechanical thermal properties (DMTA), and the biodegradation test after composting and performing optical microscopy (OM) of the blends were investigated. The blend PP/PA6 compatibilized with polypropylene grafted with maleic anhydride (PPMA) was also obtained and used as a reference. The results showed that the PP/PA6/PPMA revealed a more homogeneous morphology and resulted in higher modulus; nevertheless, the sample obtained with the lower molar mass PDLLA as an alternative for PPMA showed a storage modulus behavior close to the reference material. Poly(LA‐co‐ε‐CL) and PCL also showed changes in the morphology of the PA6 dispersed phase. Positive results were observed in the biodegradation test examined by OM for all samples containing BPs. The novelty of this work was to employ BPs as compatibilizing agents of the blends comprising PP/PA6, producing ternary blends with superior mechanical properties due to the better dispersion of the phases.

Alternative methods for the pilot-scale production and characterization of chitosan nanoparticles.

This work describes the production/characterization of low molar mass chitosan nanoparticles derived from waste shrimp shells (SSC), as well as from a commercial chitosan (CC). The production of low molar mass nanochitosan employed thermal shock, alternating between 100 °C and ambient temperature, followed by grinding the dry material (SSC and CC) in a ball mill, producing around 500 g of nanochitosan per batch. A highlight of the methodology employed is that it enables nanochitosan to be obtained even from a low quality commercial raw material. All particles had diameters smaller than 223 nm, with an average diameter below 25 nm (determined by DLS), while reductions of molar mass were between 8.4-fold and 13.5-fold. The depolymerization process resulted in a reduction in crystallinity of 38.1 to 25.4% and 55.6 to 25.9% in the CC and SSC samples, respectively. The production of nanochitosans was also confirmed by TEM through the observation of crystalline domains with diameters between 5 and 10 nm. This work perfectly reproduces the results on bench scale from previous research. The simple and inexpensive processes enable easy scale-up, representing an important advance in the production chain of biopolymers. Graphical abstract.

Cationic starch intercalated montmorillonite nanocomposites as natural based adsorbent for dye removal

Cationic starch intercalated montmorillonite (Mt-CST) adsorbent was developed for the removal of basic dyes, namely, Basic Blue (BB66) and Basic Yellow (BY1) from aqueous solution. Cationic starches (CST) containing ammonium groups with the degree of substitution of 0.16 (CST1) and 0.69 (CST2) were successfully prepared from the reaction of low molar mass starch with (3-chloro-2-hydroxypropyl trimethyl) ammonium chloride. A series of Mt-CST nanocomposites were prepared by controlling the mass ratios of Mt:CST. Adsorption of BB66 and BY1 from aqueous solution onto Mt-CST was studied. The adsorption capacity increased with decreasing of cationic groups in the CST or increasing the mass ratios of Mt:CST. The results showed that the Mt-CST11 nanocomposite with the mass ratio of Mt:CST1 of 69: 31 exhibited relatively high adsorption capacities for basic dyes. The results of adsorption behaviors of BY1 on Mt-CST11 and Mt-CST21 indicated that the adsorption processes followed well the Langmuir isotherm.

Catalysis in polymerization of cyclic esters. Catalyst and initiator in one molecule. Polymerization of ε-caprolactone

This study demonstrates that in the cationic ring-opening polymerization of cyclic esters, leading to biocompatible and biodegradable polymers, catalyst and initiator could be efficient when are in the same molecule (CINICAT). This is in contrast to the known processes when organocatalysts (e.g., protonic acids) require addition of an independent initiator and then low molar mass catalyst is left free in polymer. We have shown that hydroxymethyl phosphonic acid and 11-hydroxyundecaphosphonic acid act simultaneously as catalysts and initiators, becoming stable end-groups of the macromolecules (MALDI and DOSY). It follows from kinetic analysis that polymerization with these CINICATs is living/controlled.

Low purity enzymes and ultrasound pretreatment applied to partially hydrolyze whey protein

The hydrolysis of whey protein isolate with low purity enzymes was studied with application of ultrasound pre-treatment. The aim was to increase the degree of hydrolysis and produce new biologically active peptides. The experiments were carried out with hydrolysis times up to 24 h. The influence of temperature, pH, enzymes (pepsin and papain), substrate concentration, and use or not of the ultrasonic probe was investigated. The peptide's structure and profile were examined after exposure to ultrasound. The highest degree of hydrolysis occurred with the use of pepsin for 10 h, 37 °C, and pH 2.5. The ultrasound pre-treatment allowed a reduction of 6 h in the process. After partial enzymatic hydrolysis and ultrasound pretreatment a higher proportion of low molar mass peptides were observed at 1000–2000 g.mol-1. In vitro simulated digestion showed slight differences in peptide profile indicating that active compounds were preserved intact with a slight impact on bioactivity.

Synthesis and simulation of a distillation columns system for the propylene glycols mixtures separation

AbstractFour sequences were synthesized and simulated for the separation process of the propylene glycols mixtures: the direct, the indirect, and two proposed sequences. The simulation of the distillation columns system was performed with PRO/II program using a complete NRTL (nonrandom two‐liquids) thermodynamic model. Two mixtures were subject of the separation: one containing only propylene glycols, and another containing in addition a significant amount of water. The disadvantage of the direct and indirect sequences is that the columns are operated at high temperatures in the bottoms this fact leading to decomposition of propylene glycols. The proposed separation sequences aim to eliminate this disadvantage by taking into account the nearest effect of inert gas that water and propylene glycols with lower molar mass have on the separation mixture. The feed is introduced directly in the reboiler of the first column, where lower glycols and water act as an inert gas on the TePG vaporization. The proposed separation sequence of the propylene glycols and water mixture has a temperature in the reboiler with approximately 13 K lower beside the direct sequence.

Hyaluronic Acid in the Intestinal Tract: Influence of Structure, Rheology, and Mucoadhesion on the Intestinal Uptake in Rats.

Oral hyaluronic acid (HA) is a ubiquitous biopolymer that has gained attention as a treatment for local or systemic diseases. Here, we prepared and characterized structures of free HA (f-HA) with a high (>105 Da), intermediate (≤105 Da), and low (≤104 Da) average molar mass (MM); nanoparticles crosslinked with adipic dihydrazide (n-HA); and mixed formulations (mixed-HA) containing f-HA and n-HA. MM distribution determined the structure, hydrodynamic diameter, and zeta potential of the f-HAs. Crosslinking changed the physicochemical properties in n-HA. In vitro tack adhesion assays, using mucin tablets or a viable rat intestinal mucosa, showed better mucoadhesion with f-HA (intermediate MM) and mixed-HA (25% n-HA), especially in the jejunum segment. High MM f-HA presented negligible mucoadhesion. n-HA showed the deepest diffusion into the porous of the membranes. In vivo results showed that, except for high MM f-HA, there is an inverse relationship between rheological changes in the intestinal membrane macerates resulting from mucoadhesion and the effective intestinal permeability that led to blood clearance of the structures. We conclude that the n-HA formulations are promising for targeting other tissues, while formulations of f-HA (intermediate MM) and mixed-HA are better for treating dysbiosis.

New trivalent phosphorus containing poly(arylene ether)s as alternative reactants for the Mitsunobu reaction

Novel phosphine containing poly(arylene ether)s with trivalent phosphorus are prepared by reaction of bis(4-fluorophenyl) phenylphosphine with 2,2-bis(4-hydroxyphenyl)propane. The reaction conditions are adjusted to avoid partial oxidation of the phosphine derivative during polycondensation. Solution polycondensation results in copolymers with phosphine and phosphorus oxide containing repeating units with high molar contents of phosphine oxide (up to 45 mol% P = O repeating units), while solvent-free melt polycondensation of bis(4-fluorophenyl) phenylphosphine with bis(trimethylsilyl)-2,2-bis(4-oxyphenyl)propane and CsF as catalyst yields 85 mol% phosphine containing repeating units. The weight-averaged molar masses are in the range of 40,000 g/mol.The phosphine containing polymers are used, to illustrate an example, as polymeric reagent in the Mitsunobu reaction for the etherification of 5-hydroxyisophthalic acid dimethylester with henicosaperfluoroicosanol to yield a monomer for semifluorinated polyesters. The Mitsunobu reaction requires triaryl phosphine derivatives as reactants which are oxidized to phosphorus(V) compounds during the course of the reaction. The separation of the oxidized products in the reaction with triphenyl phosphine (TPP) is generally complicated and the application of the novel poly(aryl ether)s results in simplification of the work-up and increase of the yield of the desired product (33% with TPP vs. 55% with the phosphine containing poly(aryl ether) P13). Thus, the applicability of the polymers as polymer-supported phosphine derivatives replacing low molar mass phosphines is demonstrated.

Hydrodynamic Compatibility of Hyaluronic Acid and Tamarind Seed Polysaccharide as Ocular Mucin Supplements.

Hyaluronic acid (HA) has been commonly used in eyedrop formulations due to its viscous lubricating properties even at low concentration, acting as a supplement for ocular mucin (principally MUC5AC) which diminishes with aging in a condition known as Keratoconjunctivitis sicca or “dry eye”. A difficulty has been its short residence time on ocular surfaces due to ocular clearance mechanisms which remove the polysaccharide almost immediately. To prolong its retention time, tamarind seed gum polysaccharide (TSP) is mixed as a helper biopolymer with HA. Here we look at the hydrodynamic characteristics of HA and TSP (weight average molar mass Mw and viscosity ) and then explore the compatibility of these polymers, including the possibility of potentially harmful aggregation effects. The research is based on a novel combination of three methods: sedimentation velocity in the analytical ultracentrifuge (SV-AUC), size-exclusion chromatography coupled to multiangle light scattering (SEC-MALS) and capillary viscometry. HA and TSP were found to have ) kg/mol and ) kg/mol respectively, and and ml/g, respectively. The structure of HA ranges from a rodlike molecule at lower molar masses changing to a random coil for Mw > 800 kg/mol, based on the Mark–Houwink–Kuhn–Sakurada (MHKS) coefficient. TSP, by contrast, is a random coil across the range of molar masses. For the mixed HA-TSP systems, SEC-MALS indicates a weak interaction. However, sedimentation coefficient (s) distributions obtained from SV-AUC measurements together with intrinsic viscosity demonstrated no evidence of any significant aggregation phenomenon, reassuring in terms of eye-drop formulation technology involving these substances.

Rising the molecular mobility of polyvinyl butyral by plasticizers: towards energy storage applications

The versatile behaviour of poly-vinylbutyral (PVB) and its ability to form quasi-solid polymer electrolytes (SPE) with reliable ionic mobility, has been investigated over the temperature range from 120 K to 350 K, by mechanical and dielectric spectroscopic measurements. Enhancements in the polymer chain flexibility, due to the addition of low molar mass organic liquid plasticizers (acetonitrile, AcN, and methoxy-propionitrile, MPN) favouring the long-range motion of charge carriers, give rise to a room temperature ionic conductivity which in the hybrid PVB/MPN/LiI system increases of about 3 and 9 orders of magnitude with respect to the counterparts PVB/LiI and pure dry-PVB system, respectively. This result proves the existence of coupling between cooperative segmental motion and ion dynamics in such kind of materials.