Preparation and Characterization of Biodegradable Polyurethane Nanocomposites Based on Poly(3-hydroxybutyrate) and Poly(Butylene Adipate) Using Reactive Organoclay

Polyurethane nanocomposites were synthesized using one-step solution polymerization of poly(3-hydroxybutyrate)-diol, poly(butylene adipate)-diol using 1,6-hexamethylene diisocyanate. Nanocomposites were prepared using an in-situ polymerization method. The structure was verified using FTIR and ¹HNMR. Morphology was examined by XRD and TEM methods. Thermal properties were examined using DSC and TG. DSC showed that all samples were semicrystalline. The Cloisite 30B enhanced the melt crystallization of PHB segments while hindering those of the PBA segments. Thermal stability was improved compared to the neat PUs samples. The Coats-Redfern model was used to calculate the activation energy. Mechanical properties were improved with incorporation of organoclays.     

Synthesis and characterization of a new compound bearing ketone and hydroxyl groups for preparation of ambient temperature self-crosslinking waterborne polyurethanes

A new crosslinker for polyurethane, N-[(1,1-dimethyl-2-acetyl)ethyl]-β-dihydroxy ethylamino propanamide (DDP), was synthesized by Michael reaction using diethanolamine (DEA) and diacetone acrylamide (DAAM). DDP is a dihydroxyl-containing compound with ketone moiety, which crosslinks during film formation through a reaction between ketone of DDP and hydrazide in water-soluble dihydrazide compound, added upon preparation of waterborne polyurethane. The optimal ratio of DEA/DAAM for Michael reaction, determined by gas chromatography (GC), was of 1.05 mol; highest yields (80%) were obtained with this ratio when the reaction was carried out at 90 °C with 12 h of reaction time using acetonitrile as solvent. Experimental conditions of DDP separation from the reaction mixture were predetermined first through thin-layer chromatography, and DDP separation was conducted by column chromatography. DDP with 97% of purity or higher was obtained. The structure of DDP was fully characterized by IR and NMR. The elemental composition and molecular weight of DDP were confirmed by high resolution GC–MS and HPLC–MS, respectively. Polyurethane latexes with DDP and post-added dihydrazide were prepared, and polymer film properties compared with DDP-free latex film. Tensile strength increased with a decrease in elongation in crosslinked polymers. Higher performance in water and solvent adsorptions was also detected.     

Fabrication and evaluation of polyurethane cationic surfactants,and their potential on silver nanoparticles stability,surface activity,and biological activity

The aggregation behavior and stability of silver nanoparticles (AgNs) are important considerations when exposed to various environments. AgNs have significant interests due to their unique properties. The cationic polymeric surfactants were investigated to coat or cape AgNs with a semi-permeable layer. Using Fourier Transform Infrared Spectroscopy and Gel permission chromatograph, the chemical structures were verified. Through the use of transmission electron microscopy, ultraviolet spectroscopy, particle size distribution, zeta potential, surface activities, and anti-bacterial activity, the produced cationic PUQOS and PUQLS surfactants containing silver nanoparticles were assessed. The results indicate that silver nanoparticles were stabilized in solution for seven days without aggregation using the prepared surfactants by coating their surfaces. The coating processes altered the zeta potential. The prepared polymeric surfactants with silver nanodispersion demonstrated practical activities against various standard G (+ve) and G (?ve) bacteria, yeast, and fungi.