The design, preparation, and properties of planar multilayer structures composed of various combinations of sequentially deposited polyelectrolyte (PE) chains and self-assembled layers of individual block copolymer aggregates (vesicles, micelles, or large compound micelles (LCMs)) are described. The aggregates contain negatively or positively charged corona chains while the PE multilayers contain alternating polyanionic or polycationic chains deposited on silicon wafers. The final structures consist of combinations of layers of various charged species: multilayers of alternating PEs of poly(allyl hydrochloride) (PAH) and poly(acrylic acid) (PAA) as well as vesicles, micelles, or large compound micelles of ionized poly(styrene)-b-poly(4-vinylpyridine) (PS-b-P4VP) or of poly(styrene)-b-poly(acrylic acid) (PS-b-PAA). Two types of layer-by-layer (LbL) multilayer structures were studied: individual aggregate layers sandwiched between PE multilayers and layers of individual aggregates of various morphologies and of different corona chain charges, deposited on top of each other without intermediate multilayers or individual layers of PEs. The strong interactions between the successive layers are achieved mainly by electrostatic attraction between the oppositely charged layers. The planar LbL multilayers containing block copolymer aggregates could, potentially, be used as carriers for multiple functional components; each aggregate layer could be loaded with hydrophobic (in the core of the micelles, LCMs, or vesicle walls) or hydrophilic functional molecules (in the vesicular cavities). The overall thickness of such planar LbL multilayers can be controlled precisely and can vary from tens of nanometers to several micrometers depending on the number of layers, the sizes of the aggregates, and the complexity of the structure.
Properties PDLA PLLA PDLLA Solubility All are soluble in benzene, chloroform, acetonitrile, tetrahydrofuran (THF), dioxane etc., but insoluble in ethanol, methanol, and aliphatic hydrocarbons Crystalline structure Crystalline Hemicrystalline Amorphous Melting temperature (T m )/ °C ~180 ~180 Variable Glass transition temperature (T g )/ °C 50-60 55-60 Variable Decomposition temperature/°C ~200 ~200 185-200 Elongation at break/ (%) 20-30 20-30 Variable Breaking strength/ (g/d) 4.0-5.05.0-6.0Variable Half-life in 37°C normal saline 4-6 months 4-6 months 2-3 months Table 1.Selected physical and chemical properties of PLA.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Abstract Skin wounds on stretchable parts of the body including the elbows, knees, wrists, and nape usually undergo delayed and poor healing due to the interference of their frequent motion. Ordinary dressings that are not flexible enough face difficulty to promote wound healing due to the mismatching between the mechanics of the dressing materials and the wounds. In this study, an injectable, biocompatible, self‐healable, and conductive material poly(3,4‐ethylenedioxythiophene): poly(styrenesulfonate)/guar slime (PPGS) is developed for healing wounds with various kinds of movements. As a proof‐of‐principle assay, the healing effect of PPGS is explored on a skin wound model on the nape of rats that often experiences frequent movements. PPGS, which can be prepared within 1 min, successfully accelerates the healing of the wounds. The results suggest that PPGS has great potential in the fields of tissue engineering and biomedicine.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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