Characterisation of Blends Based on Hydroxyethylcellulose and Maleic Acid-alt-Methyl Vinyl Ether

Interpolymer Complexes Based on Cellulose Ethers: Application

Interpolymer complexes based on cellulose ethers have gained significant interest in recent years due to their versatile applications. These complexes are formed by combining different polymers through non-covalent interactions, resulting in stable structures. This article provides an overview of the various fields where IPCs based on cellulose ethers find application. IPCs based on cellulose ethers show great potential in drug delivery systems. These complexes can encapsulate drugs and enable controlled release, making them suitable for sustained drug delivery. They offer advantages in terms of precise dosage and enhanced therapeutic efficacy. Coatings and adhesives also benefit from IPCs based on cellulose ethers. These complexes can form films with excellent mechanical strength and enhanced water resistance, providing durability and protection. They have applications in various industries where coatings and adhesives play a crucial role. In food packaging, IPCs based on cellulose ethers are highly relevant. These complexes can form films with effective barrier properties against oxygen and water vapor, making them ideal for packaging perishable foods. They help extend to shelf life of food products by minimizing moisture and oxygen transfer. Various methods, such as solvent casting, coacervation, and electrostatic complexation, are employed to synthesize IPCs based on cellulose ethers.

Temperature/pH-Sensitive Double Cross-Linked Hydrogels as Platform for Controlled Delivery of Metoclopramide

Novel double cross-linked (DC) hydrogels with pH-/temperature-sensitive properties were designed and developed. Therefore, linear pH-sensitive poly(methyl vinyl ether-alt-maleic acid) (P(VME/MA)) macromolecules were absorbed within a thermosensitive poly(N-isopropylacrylamide-co-hydroxyethylacrylamide)-hydrogel (PNH) and, subsequently, cross-linked together through a solvent-free thermal method. As a novelty, double cross-linked hydrogels were obtained from previously purified polymers in the absence of any solvent or cross-linking agent, which are generally harmful for the body. The new DC structures were characterized by FT-IR spectroscopy, SEM, swelling kinetic measurements, and mechanical tests. The resulting scaffolds exhibited interconnected pores and a flexible pattern, compared to the brittle structure of conventional PNH. The swelling kinetics of DC hydrogels were deeply affected by temperature (25 and 37 °C) and pH (7.4 and 1.2). Furthermore, the hydrogels absorbed a great amount of water in a basic environment and displayed improved mechanical properties. Metoclopramide (Met) was loaded within DC hydrogels as a model drug to investigate the ability of the support to control the drug release rate. The results obtained recommended them as convenient platforms for the oral administration of drugs, with the release of the largest part of the active principle occurring in the colon.

High Yield Poly(ethylene-alt-maleic acid) Grafting to Wood Pulp while Minimizing Fiber/Fiber Wet Adhesion

Heating bleached kraft pulps treated with poly(ethylene-alt-maleic acid) (PEMAc) can lead to high yields of carboxylated polymer grafted to fibers. However, in many cases, the cured, dry pulp cannot be effectively repulped (redispersed in water) because the wet strength is too high. Impregnation with PEMAc solutions at pH 4 followed by high temperature (120-180 °C), catalyst-free curing for short times can give fixation yields >85% while maintaining repulpability. The combination of high fixation yields with low wet strength is possible because the extent of curing required for high grafting yields is less than the curing requirement for high wet strength. Two challenges in moving this technology to practicable applications are (1) identifying the optimum laboratory pulp curing conditions and (2) translating laboratory curing conditions to industrial processes. A modeling tool was developed to meet these challenges. The model is based on the observation that for curing conditions giving high fixation yields the wet tensile indices of grafted pulp sheets showed a power-law dependence on the βΓ product where β is the conversion of the succinic acid moieties in PEMAc to the corresponding succinic anhydride groups in the curing step and Γ is the amount of polymer applied to the pulp. For two PEMAc molecular weights and two pulp types, the power-law slopes were 0.6; however, the pre-exponential terms depended upon the specific polymer and pulp type combination. We propose that the relationships between the wet tensile index and βΓ, from polymer-treated, laboratory pulp handsheets, can be used to predict if proposed curing conditions for larger-scale processes will produce a repulpable product.

A new sponge-type hydrogel based on hyaluronic acid and poly(methylvinylether-alt-maleic acid) as a 3D platform for tumor cell growth

A new sponge-type hydrogel was obtained by cross-linking hyaluronic acid (HA) and poly(methylvinylether-alt-maleic acid) P(MVE-alt-MA) through a solvent-free thermal method. The sponge-type hydrogel was characterized and checked as a support for cell growth. The influence of concentration and weight ratio of polymers on the morphology and hydrogel stability was investigated. The total polymers concentration of 3% (w/w) and the weight ratio of 1:1 were optimal for the synthesis of a stable hydrogel (HA³P50) and to promote cell proliferation. The swelling measurements revealed a high-water absorption capacity of the hydrogel in basic medium. Diphenhydramine (DPH), lidocaine (Lid) and propranolol (Prop) were loaded within the hydrogel as a model drugs to investigate the ability of drug transport and release. In vitro studies revealed that HA³P50 hydrogel promoted the adhesion and proliferation of human hepatocellular carcinoma cell line HepG2, providing a good support for 3D cell culture to obtain surrogate tumor scaffold suitable for preclinical anti-cancer drug screening.

Design of Polymer Blends Based on Chitosan:POZ with Improved Dielectric Constant for Application in Polymer Electrolytes and Flexible Electronics

There is a considerable demand for the development and application of polymer materials in the flexible electronic- and polymer-based electrolyte technologies. Chitosan (CS) and poly(2-ethyl-2-oxazoline) (POZ) materials were blended with different ratios to obtain CS:POZ blend films using a straightforward solution cast technique. The work was involved a range of characteristic techniques, such as impedance spectroscopy, X-ray diffraction (XRD), and optical microscopy. From the XRD spectra, an enhancement in the amorphous nature in CS:POZ blend films was revealed when compared to the pure state of CS. The enhancement was verified from the peak broadening in CS:POZ blend films in relative to the one in crystalline peaks of the CS polymer. The optical micrograph study was used to designate the amorphous and crystalline regions by assigning dark and brilliant phases, respectively. Upon increasing POZ concentration, the dielectric constant was found to increase up to ɛ′ = 6.48 (at 1 MHz) at 15 wt.% of POZ, and then a drop was observed beyond this amount. The relatively high dielectric constant and dielectric loss were found at elevated temperatures. The increase of POZ concentration up to 45 wt.% made the loss tangent to shift to the lower frequency side, which is related to increasing resistivity. The increases of dielectric constant and dielectric loss with temperature were attributed to the increase of polarisation. The loss tangent peaks were found to shift to the higher frequency side as temperature elevated. Obvious relaxation peaks were observed in the imaginary part of electric modulus, and no peaks were found in the dielectric loss spectra. The concentration dependent of M″ peaks was found to follow the same trend of loss tangent peaks versus POZ content. The relaxation process was studied in terms of electric modulus parameters.

Characterization, mechanistic analysis and improving the properties of denture adhesives

OBJECTIVE

Denture adhesives are widely used to avoid the detachment and sliding of dentures. However, the adhesion properties can be affected by variation in mouth conditions such as the level of salivation. The objective of this study was to understand the effect of environmental conditions on the adhesion properties of a commercially available denture adhesive named as Poligrip^® Free manufactured by GlaxoSmithKline Ltd., UK and to identify the reasons for the observed variation in its adhesion strength.

METHODS

The failure mechanisms of denture adhesive have been assessed through using different physical, mechanical and thermal characterization experiments. All methods were used in different pH, temperatures, and salivation conditions and at the end, a strategy was proposed to overcome the failure of the paste in hyposalivation as well.

RESULTS

In vitro models mimicking the denture gingival interface were designed to evaluate the adhesion properties of the investigated adhesive. Changes in the adhesion strength in response to three major factors related to the oral conditions including level of salivation, pH, and temperature were measured. The results of lap shear, tensile test, and internal interactions suggested a cohesion failure, where the lowest adhesion strength was due to hyposalivation. Fourier transform infrared spectroscopy (FTIR) and rheological analysis confirmed the importance of hydrogen bonds and hydration in the adhesion strength of the paste.

SIGNIFICANCE

The investigated scenarios are widely observed in patient using denture adhesives and the clinical reports have indicated the inconsistency in adhesion strength of the commercial products. After identifying the potential reasons for such behavior, methods such as the addition of tripropylene glycol methyl ether (TPME) to enhance internal hydrogen bonds between the polymers are proposed to improve adhesion in the hyposalivation scenario.

Synthesis and Characterization of Polyaniline/Graphene Composite Nanofiber and Its Application as an Electrochemical DNA Biosensor for the Detection of Mycobacterium tuberculosis

This article describes chemically modified polyaniline and graphene (PANI/GP) composite nanofibers prepared by self-assembly process using oxidative polymerization of aniline monomer and graphene in the presence of a solution containing poly(methyl vinyl ether-alt-maleic acid) (PMVEA). Characterization of the composite nanofibers was carried out by Fourier transform infrared (FTIR) and Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM images revealed the size of the PANI nanofibers ranged from 90 to 360 nm in diameter and was greatly influenced by the proportion of PMVEA and graphene. The composite nanofibers with an immobilized DNA probe were used for the detection of Mycobacterium tuberculosis by using an electrochemical technique. A photochemical indicator, methylene blue (MB) was used to monitor the hybridization of target DNA by using differential pulse voltammetry (DPV) method. The detection range of DNA biosensor was obtained from of 10⁻⁶–10⁻⁹ M with the detection limit of 7.853 × 10⁻⁷ M under optimum conditions. The results show that the composite nanofibers have a great potential in a range of applications for DNA sensors.

Poly(vinyl alcohol)–Gantrez® AN cryogels for wound care applications

Cryotropic gelation is a low cost, well-known technique that has been used for decades for the preparation of cryogels based on poly(vinyl alcohol).

Antimicrobial hydrogels based on autoclaved poly(vinyl alcohol) and poly(methyl vinyl ether-alt-maleic anhydride) mixtures for wound care applications

Novel antimicrobial hydrogels with good mechanical and physical properties were synthesized by autoclaving aqueous mixtures of poly(vinyl alcohol) and poly(methyl vinyl ether-alt-maleic anhydride).