Butyl Rubber Nanocomposites with Monolayer MoS2 Additives: Structural Characteristics, Enhanced Mechanical, and Gas Barrier Properties

Emerging two-dimensional (2D) materialsm, such as molybdenum disulfide (MoS2), offer opportunities to tailor the mechanical and gas barrier properties of polymeric materials. In this study, MoS2 was exfoliated to monolayers by modification with ethanethiol and nonanethiol. The thicknesses of resulting MoS2 monolayers were 0.7 nm for MoS2-ethanethiol and 1.1 nm for MoS2-nonanethiol. MoS2 monolayers were added to chlorobutyl rubber to prepare MoS2-butyl rubber nanocomposites at concentrations of 0.5, 1, 3, and 5 phr. The tensile stress showed a maximum enhancement of about 30.7% for MoS2-ethanethiol-butyl rubber and 34.8% for MoS2-nonanethiol-butyl rubber when compared to pure chlorobutyl rubber. In addition, the gas barrier properties were increased by 53.5% in MoS2-ethanethiol-butyl rubber and 49.6% in MoS2-nonanethiol-butyl rubber. MoS2 nanosheets thus enhanced the mechanical and gas barrier properties of chlorobutyl rubber. The nanocomposites that are presented here may be used to manufacture pharmaceutical stoppers with high mechanical and gas barrier properties

Design of an Interpenetrating Polymeric Network Hydrogel Made of Calcium-Alginate from a Thermos-Sensitive Pluronic Template as a Thermal-Ionic Reversible Wound Dressing

Polymer-based hydrogels demonstrate superior performance when used as wound dressing. An ideal dressing should possess an active healing function, absorb wound exudates, and provide a moist interface on the wound for rapid injury repair and the prevention of pain and injury during replacement of the dressing. Thus, the aim of this study was to develop a novel, reversible, smart, interpenetrating polymeric network (IPN) by utilizing the thermosensitive network of pluronic F127 (PF127) as a template to regulate the conformation of calcium-ion-crosslinked alginate. We found that the IPN hydrogels formed soft and elastic thermosensitive networks, retaining their form even after absorbing a large amount of wound exudate. The exterior of the hydrogels was made up of a rigid calcium alginate network that supported the entire hydrogel, promoting the stability of the vascular endothelial growth factor (VEGF) payload and controlling its release when the hydrogel was applied topically to wounds. Raman spectroscopy confirmed the layered structure of the hydrogel, which was found to easily disintegrate even after moderate rinsing of the wound with cold phosphate-buffered saline. Taken together, these results show that the IPN hydrogel developed in this study could be a promising delivery platform for growth factors to accelerate wound healing

Sterically Polymer-Based Liposomal Complexes with Dual-Shell Structure for Enhancing the siRNA Delivery

The sterically polymer-based liposomal complexes (SPLexes) were formed by cationic polymeric liposomes and pH-sensitive diblock copolymer were studied for their capabilities in improving the stability with high efficiency of siRNA delivery. The SPLexes were formed a dual-shelled structure and uniform size distribution. The PEGylated outer shell could mitigate the phagocytosis and reduce the cytotoxicity. Moreover, the folated SPLexes improved 42.9× accumulation in vitro and 1.7× tumor uptake in vivo in contrast with nonfolated SPLexes. The protonated copolymer at low pH would improve the siRNA released into cytoplasm following SPLexes fusion with the endo/lysosome membrane and inhibited the protein expression to 75.6 ± 4.5% efficiently. Results of this study significantly contribute to efforts to develop lipoplexes based siRNA delivery systems