Synthesis of Organosilicon Polymers Based on Carbamide Formaldehyde Resin

The article presents the synthesis of organosilicon compounds based on industrial secondary raw materials of urea-formaldehyde resin and tetraethoxysilane. The structural characteristics of the synthesized hydrophobic polymer have been studied. Compositions of hydrophobic compositions based on synthesized poly (oligomers) have been developed and tested in concrete mixtures.

Comparing C2=O and C2=S Barbiturates: Different Hydrogen-Bonding Patterns of Thiobarbiturates in Solution and the Solid State

Carbonyl-centered hydrogen bonds with various strength and geometries are often exploited in materials to embed dynamic and adaptive properties, with the use of thiocarbonyl groups as hydrogen-bonding acceptors remaining only scarcely investigated. We herein report a comparative study of C2=O and C2=S barbiturates in view of their differing hydrogen bonds, using the 5,5-disubstituted barbiturate B and the thiobarbiturate TB as model compounds. Owing to the different hydrogen-bonding strength and geometries of C2=O vs. C2=S, we postulate the formation of different hydrogen-bonding patterns in C2=S in comparison to the C2=O in conventional barbiturates. To study differences in their association in solution, we conducted concentration- and temperature-dependent NMR experiments to compare their association constants, Gibbs free energy of association ∆Gassn., and the coalescence behavior of the N-H‧‧‧S=C bonded assemblies. In Langmuir films, the introduction of C2=S suppressed 2D crystallization when comparing B and TB using Brewster angle microscopy, also revealing a significant deviation in morphology. When embedded into a hydrophobic polymer such as polyisobutylene, a largely different rheological behavior was observed for the barbiturate-bearing PB compared to the thiobarbiturate-bearing PTB polymers, indicative of a stronger hydrogen bonding in the thioanalogue PTB. We therefore prove that H-bonds, when affixed to a polymer, here the thiobarbiturate moieties in PTB, can reinforce the nonpolar PIB matrix even better, thus indicating the formation of stronger H-bonds among the thiobarbiturates in polymers in contrast to the effects observed in solution.

Fabrication and optimization of PCL/PVP nanofibers with Lawsonia inermis for antibacterial wound dressings

Anti-infection ability and desirable air permeability (AP) are the important aspects of wound dressings that should be regulated with regard to primary polymers and antibacterial agents. This study aims to fabricate and optimize a wound dressing with antibacterial properties. For this purpose, polycaprolactone (PCL) as a hydrophobic polymer and polyvinylpyrrolidone (PVP) as a hydrophilic polymer were electrospun with Lawsonia inermis (Henna) extract as an antibacterial component based on the experiments proposed by Design-Expert software. The morphology and properties of the wound dressing were studied by scanning electron microscopy, Fourier transform infrared, and AP. The response surface method (RSM) was used to determine the optimal fiber diameter and AP of the samples as a function of the polymer concentration and feed rate. The optimal PCL/PVL/Henna wound dressing has antibacterial properties against Gram-positive and Gram-negative bacteria while being biocompatible according to the MTT assay. These fibrous structures can be used as a wound dressing to prevent infection and accelerate wound healing; thanks to proper Henna release, breathability, swelling ratio, and mechanical performance.

Studies on the modification of fly ash structure with alkaline pre-treatment as a green composite flame retardant filler

A green composite made up of renewable and recyclable materials has become one of the advanced material’s attractive topics. The smooth fly ash surface used in the green composite for flame retardancy enhancement are hard to bind with hydrophobic polymer. Thus, the surface modification of this filler is needed to increase its surface roughness and pore size to be more compatible with its polymer matrix. In this research study, the alkaline pre-treatment of fly ash has been performed by using sodium hydroxide solution (NaOH) with various concentrations (5 w/w%, 10 w/w%, 15 w/w%, 20 w/w%). For pore size and morphological of the filler’s evaluation, few analyses such as Scanning Electron Microscopy-Energy Dispersive X-Ray (SEM-EDX), Barret-Joyner-Halenda (BJH) and Brunauer-Emmett-Teller (BET) pore size and volume analysis were conducted. Treated fly ash with 20 w/w% sodium hydroxide concentration gives the better morphological structure in terms of pore diameter, volume, area and high composition of aluminium, silicon with lower calcium and sulphur contents compared to others. Hence, the potential of the physiochemical properties of the green composite produced by using this modified filler will be improved as the adhesiveness of the filler with its matrix increased.