Current Applied Polymer Science - Volume 5, Issue 1, 2022

Superparamagnetic nanoparticles, such as magnetite (Fe3O4) and maghemite (γ-Fe2O3), have been used to produce magnetic nanocomposites with several polymeric matrices including magnetic styrene-divinylbenzene nanocomposites. Through the incorporation of these nanoparticles, the nanocomposite presents superparamagnetism, low coercivity, and high magnetic susceptibility. Due to these features, magnetic nanomaterials can be removed from the site where they are inserted through an external magnetic field, thus distinguishing them from conventional systems such as those used to treat oily water, which require expensive chemical agents for removal. These properties depend directly on the size distribution of the nanoparticles and the presence or absence of interactions between the surface of the polymeric matrix and the contaminants. These materials have many applications. The objective of this article is to present a bibliographic review of the state-of-the-art evolution of magnetic styrene-divinylbenzene nanocomposites over the years. According to the reports in the literature, these systems are superior to those applied conventionally in the sectors of biotechnology, agriculture, oil/gas, and nuclear chemistry, mainly for the removal of toxic metals from aqueous media.

Piezoelectric materials are gradually becoming attractive materials for research as far as energy harvesting technologies are concerned. The piezoelectric effect is a pressure-driven phenomenon that is exhibited by various kinds of crystals, ceramics, polymers, and composites. However, polymers are preferred in piezoelectric applications owing to their flexibility and lightweight. They can easily be incorporated into electronic wearables that cover the demand for flexibility which is one of the most important requirements to improve technology. In this regard, the piezoelectric polymers are found as suitable candidates for energy harvesting. The present review provides a conclusive outlook of polymer-based piezoelectric materials in terms of doping of different fillers in different piezoelectric polymers with a special focus on polyvinylidene fluoride [PVDF] polymer to develop flexible energy harvesters. Moreover, the electrospinning process, a composite fabrication technique has been discussed to cover all the aspects of processing and optimization. Based on significant energy storage capacity PVDF-based flexible electrospun web could be effectively used in day-to-day life.

Background: Tramadol HCl (TH) is a centrally acting analgesic that is used to treat moderate to severe pain intestinal disorders. Its use is limited orally due to instability.

Objective: The study aims to develop TH Pectin-coated chitosan LDH bionanocomposite beads for colon targeting.

Methods: LDH-TH intercalation was done by precipitation reaction and it was used to prepare bionanocomposite beads of TH. The developed beads were characterized for bulk density, tap density, angle of repose, HR, CI, particle size, SEM, swelling study, drug loading, and EE. In vitro release study in pH 1.2 HCl buffer, pH 6.8 buffer, and pH 7.4 buffer was performed. The compatibility study was performed using FTIR and DSC studies.

Results: The optimised formulation (F8) was found to be spherical and smooth. All other micromeritics properties were found within the acceptable range with the particle size of 543µm to 888 µm. The amount of swelling is greatly influenced by the pectin concentration employed in the coating process. Drug loading of batches F1 to F8 ranged from 52.37% to 90.25%. % EE of batches F1 to F8 ranged from 71.92% to 88.78. FTIR and DSC studies showed no physical incompatibility between the drug and used excipients. Batch (F8) showed a more controlled release pattern at the highest coating concentration of pectin (1.5%). The stability study also revealed that there was no change in the drug release profile.

Conclusion: The developed beads can be used to target the colon to prolonged-release characteristics.

Background: Poly (methyl methacrylate) (PMMA) bone cement is widely used in orthopaedic procedures of vertebroplasty (VP) balloon kyphoplasty (BKP) and cemented total joint arthroplasty (TJA). While only very few PMMA bone cement brands are approved (by the appropriate regulatory authority) for VP and BKP, many are approved for cemented TJA. Selection of cement for these applications must be done considering a very large number of clinically relevant properties, such as injectability, setting time, maximum polymerization temperature, polymerization rate, compressive strength, fracture toughness, fatigue life, and cytocompatibility. In the literature, there is a shortage of studies on methodologies for the selection of PMMA bone cement.

Purpose: The present work addresses the aforementioned shortcoming of the literature.

Methods: Three material selection methodologies (Desirability, Utility, and Weighted Property Index Methods) were applied to two study sets. Study Set 1 comprised three experimental types of bone cement for VP or BKP and five in vitro values of clinically-relevant cement properties and Set 2 comprised six approved antibiotic-loaded bone cement (ALBC) brands for cemented TJA and in vitro values of four clinically-relevant cement properties.

Results: For each of the study sets, slight differences in the ranks of the materials were found depending on the selection methodology used, but when all the selection methodologies were considered, there was clear differentiation in ranks. The relative attractions and challenges of the three selection methodologies used are highlighted.

Conclusion: Decision makers in orthopaedic hospitals and clinics as well as orthopaedic surgeons, should find the results of the present study useful.

Background: The published models were sophisticated and described the expansion in dependence on time only in the first stage. The object was to explain the discrepancy between foaming under pressure release XPS and foaming by heat supply EPS by model calculations.

Methods: The rate of expansion of small samples comprising blowing agent and polystyrene was measured by buoyancy in a silicone bath at 110 °C and that of extrusion on photographs of the volume increase after the nozzle. A viscosity model and a diffusion model were established, and experimental data were compared with calculated data.

Results: The expansion rate in the silicone bath was about 100 times slower than that in extrusion at the same nozzle temperature. The velocity of foaming in the bath by heat supply was observed to be dominated by viscosity and that of foaming under pressure release in extrusion to be stirred by diffusion. Calculations according to the viscosity model allowed the description of foaming in silicone, and the diffusion model reproduced the data of extrusion.

Conclusion: The common feature of both models was their simplicity. According to the models, the efficiency of blowing agents was only dependent on the molecular weight and on the solubility. The time determining influence on foaming was diffusion in extrusion of XPS and viscosity for expansion of EPS in silicone bath and water vapor.

Aims: The objective of the present work is to understand the structural stability (i.e., H-bonding and other weak noncovalent interactions) and electronic features of new model substrates, such as methyl orange (MO), vanadium oxide (V), surfactants as Triton-X100 (TX-100), and their allied substrate-surfactant model complexes (MO-V, MO-TX100, V-TX100, and (MO-V)-X100) with the deployment of density functional theory (DFT) method followed by electronic structure calculations and quantum theory of atoms in molecules (QTAIM) approaches.

Background: Significant interactions appear to play a major role in reducing the energy gap between the model substrates Methyl Orange (MO)/Vanadium Oxide (V)/MO-V) and surfactant/catalyst Triton-X100 (TX-100) and enhancing the catalytic behaviour of the surfactant/catalyst TX-100.

Objective: The main objective of the present report is to conduct computational experiments on the designing, characterization, structure, stability, and electronic feature analyses of substrates-surfactant model complexes constituted from Methyl Orange (MO), Vanadium Oxide (V), Triton-X100 (TX-100) units which could indeed help in synthesizing novel materials as a catalyst, controlling the reaction path by tuning such interesting interactions between a catalyst/surfactant and substrate.

Methods and Material: The quantum chemical calculations have been performed using Gaussian 09 electronic structure calculations program. B3LYP exchange-correlation functional in conjunction with 6-31G(d,p) basis set has been employed along with the incorporation of the effective core potential (ECP) based basis set for vanadium ‘V’ atom.

Results: In the present report, the computational experiments have been conducted to probe the structural, stability, and electronic features of four substrates-surfactant model complexes (SSMC) [MO-V, MO-TX-100, V-TX-100, and (MO-V)-TX-100] acquired from the substrates MO and V or the combination of both as MO-V and surfactant/catalyst TX-100. The HOMO-LUMO energy gap of the (MO-V)-TX-100 SSMC complex (0.679 eV) is found to be the lowest among all [MO-V (3.691 eV), MO-TX-100 (3.321 eV), and V-TX-100 (3.125 eV)] SSMCs, which appears mainly due to the presence of surfactant/catalyst (TX-100), thus showing its high reactivity/catalytic behaviour.

Conclusion: The calculated binding energy, change in Gibbs free energy, natural charges, and the QTAIM based topological parameters show the most favourable stabilization (H-bonding and noncovalent interactions, including metal/non-metal bonding) and interactions in the (MO-V)-TX-100 SSMC, indicating the presence of the TX-100 surfactant.

Background: Polyhydroxyesters prepared from epoxy and organic acids are vitrimers that can rearrange their topology from exchange reactions enhanced by catalysts, forming crosslinked networks that can be deformed and remolded.

Objectives: In this work, the curing kinetics and thermal properties of polyhydroxyesters vitrimers based on polyethylene glycol diglycidyl ether (PEGDGE), citric acid (CA), and sebacic acid (SA) in the presence and absence of tin octoate (Sn(Oct)2) were investigated.

Methods: Differential scanning calorimetry (DSC) non-isothermal experiments and Ozawa models were used for the curing kinetic studies, and thermogravimetry analysis (TGA) and thermomechanical analyses (TMA) were employed to investigate the thermal behavior of the networks.

Results: The highest curing enthalpy of these exothermic reactions was observed in the binary system PEGDGE:CA without catalyst (326 J/g). The addition of Sn increases the reaction enthalpy for formulations with SA and decreases it for formulations rich in CA. The lowest activation energy was shown for the formulation PEGDGE:CA = 3:2 containing 1 mol% of Sn (56 kJ/mol). The polyhydroxyesters presented Tg ranging from -24 to -48 °C, and the Tg decreased when the proportion of SA was increased in the formulation. The thermal stability was increased when the SA content increased and decreased when the content of Sn increased from 1 to 5 mol%.

Conclusion: Esterification of PEGDGE and organic acids (SA and CA) occurs even in the absence of catalyst, producing rubbery polyesters, but the use of Sn(Oct)2 decreases the curing time. Ternary networks of polyhydroxyesters containing Sn showed a discontinuity in the thermal expansion around 180°C attributed to exchange reactions, similarly to what was theorized for this class of vitrimer material.