Thermal analysis of disulfonated poly(arylene ether sulfone) plasticized with poly(ethylene glycol) for membrane formation

Effect of Plasticization/Annealing on Thermal, Dynamic Mechanical, and Rheological Properties of Poly(Lactic Acid)

This study investigates the use of low molecular weight poly(ethylene glycol) (PEG) as a plasticizer for poly(lactic acid) (PLA). PLA/PEG blend films were prepared using the solvent casting method with varying mixing ratios. The films were analyzed using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and dynamic rheological analysis. The results indicate that the addition of PEG as a plasticizer affects the thermal and mechanical properties of the PLA/PEG blend films. The study found that the glass transition and cold crystallization temperatures decreased with increasing PEG content up to 20 wt%, while the crystallinity and crystallization rate increased. The blends with up to 20 wt% PEG were miscible, but phase separation occurred when the plasticizer content was increased to 30 wt%. Subsequently, amorphous samples of neat PLA and PLA plasticized with 10 wt% of PEG underwent annealing at various temperatures (Ta = 80-120 °C) for durations ta of 1 and 24 h. The samples were then analyzed using DSC and DMA. The addition of PEG to PLA altered the content of α' and α crystalline forms compared to neat PLA at a given (Ta; ta) and favored the formation of a mixture of α' and α crystals. The crystallinity achieved upon annealing increased with increasing Ta or ta and with the incorporation of PEG.

Ductile, High-Lignin-Content Thermoset Films and Coatings

In the context of transitioning toward a more sustainable use of natural resources, the application of lignin to substitute commonly utilized petroleum-based plastics can play a key role. Although lignin is highly available at low cost and presents interesting properties, such as antioxidant and UV barrier activities, its application is limited by its low reactivity, which is a consequence of harsh conditions normally used to extract lignin from biomass. In this work, the use of glyoxylic acid lignin (GA lignin), rich in carboxylic acid groups and hence highly reactive toward epoxy cross-linkers, is presented. GA lignin, which is directly extracted from biomass via a one-step aldehyde-assisted fractionation process, allowed the preparation of thermoset films and coatings via a simple reaction with sustainable poly(ethylene glycol) diglycidyl ether and glycerol diglycidyl ether cross-linkers. This allows one to prepare freestanding films containing up to 70 wt % lignin with tunable mechanical properties and covalently surface-attached coatings containing up to 90 wt % lignin with high solvent resistance. Both films and coatings display antioxidant properties and combine excellent UV barrier activity with high visible transparency, which is attractive for applications in sustainable food packaging.

Insights into the formulation properties, biocompatibility, and permeability of poorly water-soluble methoxyflavones with PEG400 and propylene glycol

Herein, thermal and non-thermal techniques were used to elucidate the putative physical and chemical interactions between poorly water-soluble Kaempferia methoxyflavones and PEG400/propylene glycol. Additionally, the biocompatibility of methoxyflavone-glycol solutions was evaluated using Caco-2 cells whereas the absorptive transport was investigated by measuring the apparent permeability coefficient (P app) of the methoxyflavones and transepithelial electrical resistance (TEER) of the Caco-2 cell monolayer. Data from differential scanning calorimetry, Fourier-transform infrared (FTIR), and proton nuclear magnetic resonance (1H NMR) spectroscopic analysis revealed physico-chemical compatibility between the three methoxyflavones and PEG400/propylene glycol. Furthermore, PEG400 and propylene glycol solutions of the methoxyflavones were shown to be compatible with Caco-2 cells at pharmacologically effective concentrations. In vitro transport studies across the Caco-2 cell monolayer revealed high P app values of 24.07 × 10-6 to 19.63 × 10-6 cm s-1 for PEG400 solutions of the methoxyflavones. The TEER values of the Caco-2 cell monolayers indicated that the increased drug transport was partly due to increased tight junction openings, but without compromising the epithelial barrier integrity. The good pharmaceutical and biocompatibility profiles, as well as improved transport of the methoxyflavones in PEG400 and propylene glycol solutions, are suggestive of the worthiness of this approach for further consideration pertaining to the development of these drugs into oral liquid dosage forms.

Synthesis of Sulfonated Poly(Arylene Ether Sulfone)s Containing Aliphatic Moieties for Effective Membrane Electrode Assembly Fabrication by Low-Temperature Decal Transfer Methods

The purpose of this study was to investigate the effect of the aliphatic moiety in the sulfonated poly(arylene ether sulfone) (SPAES) backbone. A new monomer (4,4'-dihydroxy-1,6-diphenoxyhexane) was synthesized and polymerized with other monomers to obtain partially alkylated SPAESs. According to differential scanning calorimetry analysis, the glass transition temperature (Tg) of these polymers ranged from 85 to 90 °C, which is 100 °C lower than that of the fully aromatic SPAES. Due to the low Tg values obtained for the partially alkylated SPAESs, it was possible to prepare a hydrocarbon electrolyte membrane-based membrane electrode assembly (MEA) with Nafion® binder in the electrode through the use of a decal transfer method, which is the most commercially suitable system to obtain an MEA of proton exchange membrane fuel cells (PEMFCs). A single cell prepared using this partially alkylated SPAES as an electrolyte membrane exhibited a peak power density of 539 mW cm-2.

Metal-Organic Decomposition-Mediated Nanoparticulate Vanadium Oxide Hole Transporting Buffer Layer for Polymer Bulk-Heterojunction Solar Cells

In this study, a solution-processable compact vanadium oxide (V₂O₅) film with a globular nanoparticulate structure is introduced to the hole transport layer (HTL) of polymer bulk-heterojunction based solar cells comprised of PTB7:PC₇₀BM by using a facile metal-organic decomposition method to replace the conventionally utilized poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). For this, a biocompatible structure-determining agent, polyethylene glycol (PEG, M_n 300), is used as an additive in the precursor to form the nanoparticulate compact V₂O₅ (hereafter referred to as NP-V₂O₅) film, which possesses an outstandingly smooth surface morphology. The introduction of NP-V₂O₅ HTL via the solution process with a neutral pH condition successfully improved the stability by preventing the decomposition of indium tin oxide (ITO) glass and the penetration of heavy-metal components and moisture, which are considered as the crucial drawbacks of using PEDOT:PSS. Over 1440 h (60 days) of the stability test, an organic solar cell (OSC) with NP-V₂O₅ showed a significant durability, maintaining 82% of its initial power conversion efficiency (PCE), whereas an OSC with PEDOT:PSS maintained 51% of its initial PCE. Furthermore, due to the positive effects of the modified surface properties of NP-V₂O₅, the PCE was slightly enhanced from 7.47% to 7.89% with a significant improvement in the short-circuit current density and fill factor.

Investigation of dissolved cellulose in development of buccal discs for oromucosal drug delivery

Mucoadhesive formulations have a wide scope of application for both systemic and local treatment of various diseases. In the case of recurrent aphthous stomatitis, to ensure effective therapy, the concentration of corticosteroids, and/or anesthetics at the mouth ulcer side should be maintained with minimal systemic absorption. Therefore, the aim of the study was to investigate cellulose-based formulations, in achieving suitable hardness, mucoadhesiveness, and sustained release of the active ingredients directed towards the mucosa for an extended period of time (∼4 h). This was examined by creating polymer reinforced cellulose composites which consisted of porous cellulose discs (CD) and different polymer components namely polyethylene glycol 6000 (PEG6000), polyethylene glycol 400 (PEG400), and ethyl cellulose. Empty CDs were formed by dropping dissolved cellulose into coagulation medium. The empty porous CDs were immersed into different drug loading solutions which were prepared by dissolving three different concentrations of triamcinolone acetonide and lidocaine hydrochloride in five different ratios of PEG 6000:PEG 400:ethanol (w:w:w %) solutions. All formulations were investigated regarding drug content, release, hardness, and mucoadhesive properties. The results indicate that the non-dispersing buccal discs had sufficient hardness, drug content and in vitro release properties, but further studies are needed to achieve proper mucoadhesiveness.

Practical Considerations for Determination of Glass Transition Temperature of a Maximally Freeze Concentrated Solution

Glass transition temperature is a unique thermal characteristic of amorphous systems and is associated with changes in physical properties such as heat capacity, viscosity, electrical resistance, and molecular mobility. Glass transition temperature for amorphous solids is referred as (T g), whereas for maximally freeze concentrated solution, the notation is (T g'). This article is focused on the factors affecting determination of T g' for application to lyophilization process design and frozen storage stability. Also, this review provides a perspective on use of various types of solutes in protein formulation and their effect on T g'. Although various analytical techniques are used for determination of T g' based on the changes in physical properties associated with glass transition, the differential scanning calorimetry (DSC) is the most commonly used technique. In this article, an overview of DSC technique is provided along with brief discussion on the alternate analytical techniques for T g' determination. Additionally, challenges associated with T g' determination, using DSC for protein formulations, are discussed. The purpose of this review is to provide a practical industry perspective on determination of T g' for protein formulations as it relates to design and development of lyophilization process and/or for frozen storage; however, a comprehensive review of glass transition temperature (T g, T g'), in general, is outside the scope of this work.