Influence of Hard Segments on the Thermal, Phase-Separated Morphology, Mechanical, and Biological Properties of Polycarbonate Urethanes

Synthesis of Poly(Trimethylene Carbonate) from Amine Group Initiation: Role of Urethane Bonds in the Crystallinity

Semi-crystalline poly(trimethylene carbonate) (PTMC) can be efficiently prepared by ring-opening polymerization (ROP) initiated by amine using various catalysts. More promising results were reached with the one-step process of stannous octanoate unlike the two-step one-pot reaction using TBD and MSA catalysts. The ROP-amine of TMC consists in a simple isocyanate free process to produce polycarbonate-urethanes, compatible with the large availability of amines ranging from mono- to multifunctional until natural amino acids. ROP-amine of TMC leads to urethane bonds monitored by FTIR spectroscopy. The relationship between the nature of amines and the crystallinity of PTMC was discussed through X-ray diffraction and thermal studies by DSC and TGA. The impact of the crystallinity was also demonstrated on the mechanical properties of semi-crystalline PTMC in comparison to amorphous PTMC, synthesized by ROP initiated by alcohol. The semi-crystalline PTMC synthesized by ROP-amine opens many perspectives.

Modelling the Stiffness-Temperature Dependence of Resin-Rubber Blends Cured by High-Energy Electron Beam Radiation Using Global Search Genetic Algorithm

Modelling the influence of high-energy ionising radiation on the properties of materials with polymeric matrix using advanced artificial intelligence tools plays an important role in the research and development of new materials for various industrial applications. It also applies to effective modification of existing materials based on polymer matrices to achieve the desired properties. In the presented work, the effects of high-energy electron beam radiation with various doses on the dynamic mechanical properties of melamine resin, phenol-formaldehyde resin, and nitrile rubber blend have been studied over a wide temperature range. A new stiffness-temperature model based on Weibull statistics of the secondary bonds breaking during the relaxation transitions has been developed to quantitatively describe changes in the storage modulus with temperature and applied radiation dose until the onset of the temperature of the additional, thermally-induced polymerisation reactions. A global search real-coded genetic algorithm has been successfully applied to optimise the parameters of the developed model by minimising the sum-squared error. An excellent agreement between the modelled and experimental data has been found.

Synthesis and property of polyurethane elastomer for biomedical applications based on nonaromatic isocyanates, polyesters, and ethylene glycol

Polyurethane (PU) elastomers were synthesized by the reaction of HDI or IPDI diisocyanates and poly(ε-caprolactone) (PCL or poly(ethylene adipate) (PA) diols and ethylene glycol as a polymer chain extender. IR, 1H, and 13C NMR spectroscopy and X-ray analysis were used for the structural analysis of the formed films. The molecular weight distribution was examined by GPC chromatography. Based on the measured contact angles, free surface energy parameters were calculated. The obtained results were analyzed for the possible use of these polyurethanes as biomaterials. The most promising in this respect was PU-3, which was synthesized from IPDI and PCL. This was due to its high molecular weight of approximately 90,000, the presence of a crystalline phase, and the relatively high hydrophobicity, with a SEP value below 25 mJ/m2. These films showed a good resistance to hydrolysis during incubation in Baxter physiological saline during 6 weeks. Both Gram-positive (Bacillus sp.) and Gram-negative (Pseudomonas sp.) types of bacterial strains were used to test the biodegradation property. Synthesized PUs are biodegradable and showed moderate or even mild cytotoxicity against human normal fibroblasts (BJ) and immortalized keratinocytes (HaCaT), estimated with direct contact assay. The most biocompatible was PU-3 film, which revealed rather mild reactivity against both cell lines, and the least was PU-2 film, synthesized from HDI and PA (severe toxicity for HaCaTs).

Synthesis and Characterization of Polyfumarateurethane Nanoparticles for Sustained Release of Bupivacaine

Biodegradable polyfumarateurethane (PFU) for use as a bupivacaine delivery vehicle, synthesized using di-(2-hydroxypropyl fumarate) (DHPF), polyethylene glycol (PEG) and 1,6-hexamethylene diisocyanate (HMDI), was designed to be degradable through the hydrolysis and enzymatic degradation of the ester bonds in its polymer backbone. Using a water-in-oil-in-water double emulsion techniques, nanoparticles encapsulating water or fluorescein isothiocyanate (FITC) were fabricated to avoid the immune system owing to the presence of PEG on their surface. The morphologies of these nanoparticles were characterized by DLS, TEM, FE-SEM, and fluorescent microscopies. The present study explored the encapsulation, loading efficiency and in vitro drug release of bupivacaine encapsulated with biodegradable PFU nanoparticles for the treatment of local anesthesia. Various concentrations of bupivacaine were encapsulated into nanoparticles and their encapsulation efficiencies and drug loading were investigated. Encapsulation efficiency was highest when 2.5% bupivacaine was encapsulated. Drug release behavior from the bupivacaine-loaded PFU nanoparticles followed a sustained release profile.

Preparation and characterization of soybean oil-based waterborne polyurethane/acrylate hybrid emulsions for self-matting coatings

This work aims to explore the feasibility of self-matting coatings based on soybean oil.

Mussel-inspired fabrication of pH-sensitive biomimetic hydrogels based on greenhouse gas carbon dioxide

Biomimetic hydrogels were prepared from carbon dioxide using a facile method. The PPC block and catechol groups contained in PPC-PU-LDA enable the hydrogel to have good cell compatibility and adhesion.