Fang Wu

Composition dependence of physical properties of biodegradable poly(ethylene succinate) urethane ionenes

To obtain an excellent comprehensive performance of poly(ethylene succinate) (PES), we have synthesized a series of poly(ethylene succinate) (PES) urethane ionenes (PESUIs) with various content of urethane ionic group by the chain extension reaction of dihydroxyl-terminated poly(ethylene succinate) and diethanolamine hydrochloride with hexamethylene diisocyanate as a chain extender, and we systematically investigated the composition dependence of the physico-chemical properties of PESUI through a series of characteristic techniques. The results of thermal and crystallization behaviors suggest that the incorporation of urethane ionic group slightly affects the glass transition temperature, melting temperature, and thermal stability, and significantly accelerates the crystallization rate of PES without changing the crystallization mechanism. The fastest crystallization rate was reached with the incorporation of 4 mol% urethane ionic groups. Spherulitic morphology observation indicates that nucleation density significantly increased, while spherulitic growth rate gradually decreased with increase in urethane ionic group content. Both complex viscosity and storage modulus initially increased and then decreased with increase in urethane ionic group content, and their maximum values were observed for the sample with 4 mol% of urethane ionic group. Mechanical properties slightly varied with urethane ionic group content.

Synthesis and characterization of a polyurethane ionene/zinc chloride complex with antibacterial properties

The 1,6-bis(N′,N-dimethyl-3-hydroxylpropyl) ammonium chloride (BQAC–diol)/zinc chloride complex was first synthesized and used as an ionic monomer to synthesize a polyurethane ionene/zinc chloride (PUI/ZnCl2) complex via its polymerization with poly(ethylene glycol) (PEG), 1,4-butanediol (BDO), and 4,4′-diphenylmethane diisocyanate (MDI). The structure and properties of the PUI/ZnCl2 complex were characterized systematically by NMR, intrinsic viscosity, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarized optical microscopy (POM), and tensile testing, and the antibacterial properties were investigated using a cylinder-plate method. The results indicated that the crystallization rate of PUI/ZnCl2 increased gradually with increasing content of ionic units, which was ascribed to the increased crystal growth rate as evidenced by POM observation. The morphology analyzed by scanning electron microscopy indicated that no apparent microphase separation occurred for the complex and ZnCl2 dispersed at a molecular level in the PUI matrix, since no particle-like species can be observed. Antibacterial properties measurement showed that the PUI containing quaternary ammonium salt cation has no antibacterial activity but the coexistence of ZnCl2 and cation exhibit a synergetic effect with respect to the antibacterial activity.

Antibacterial coordination polymer hydrogels composed of silver(I)-PEGylated bisimidazolylbenzyl alcohol

Herein, antibacterial coordination polymer hydrogels were conveniently fabricated in water via coordination between silver nitrate and PEGylated bisimidazolylbenzyl alcohol (1a–c). These coordination polymer hydrogels exhibit much better antibacterial activity than silver nitrate against both Gram-negative and Gram-positive pathogens including multidrug-resistant pathogens. The coordination polymer Ag/1c with a long PEG chain (PEG1000) was demonstrated to be the most effective antibacterial material, and its minimum inhibition concentrations (MICs) could be as low as 15.2 times for common Staphylococcus aureus and 4.8 times for methicillin-resistant Staphylococcus aureus over that of silver nitrate. With improved antibacterial performance, easy preparation method, improved stability, sustained releasability, outstanding ductility and low cytotoxicity, the as-prepared coordination polymer hydrogels should find various potential applications such as in clinical burn and wound dressings, biofilms, bioadhesives, and coatings of biomedical materials.