Morphology-controlled stabilised polyaniline nanoparticles and their electrorheological properties

Nanoparticles and sub-microparticles of the conducting polymers polyaniline (PANI), polyanisidine (PoANIS) and their copolymers were synthesised, deprotonated and dispersed in viscous media in order to study the influence of their synthetic conditions and of steric stabilisers (cellulose-based materials) on the physical, chemical and morphological characteristics of the polymers. Electrorheological (ER) measurements were performed and related to the polymer properties. The polymer particles had various loadings of stabilisers, depending on the polymer/stabiliser interactions and the stabiliser concentration. When stabilised with hydroxyethylcellulose (HEC), the PANI particles contained traces of HEC, while PoANIS, less stabilised by the electron-rich HEC molecules, did not. Stabilised PANI-HEC synthesised at 0°C readily formed small fibres that, when deprotonated, displayed a large electrorheological response (yield stress ca. 800 Pa at 3.2 kV.mm−1). PoANIS prepared under the same conditions yielded a polydisperse cenospheric material with no ER activity. </jats:p

Cell morphology and growth observation studies on novel, chemically unmodified and patterned polymer surfaces for advanced tissue culture applications

Creation of more physiologically relevant cell models in tissue culture is a requisite for advancing medical research. It can involve complex substrates, expensive manufacturing and largely inaccessible methods of increasing surface energy and patterning of materials that may be unnecessary in many circumstances. An array of various different adherent cell lines (human, mammalian, healthy and disease states) were grown on simple sterilised but otherwise untreated thin film surfaces as well as on electro-hydrodynamically patterned surfaces to produce topographically patterned culture surfaces. Room temperature cure epoxy resin and unmodified poly(methyl methacrylate) (PMMA) thin film surfaces were used for cell growth and morphological observations. Differing responses in growth, morphology and adherence were observed in a surface- and cell-specific manner. With no complex and expensive modifications required, we demonstrate the application of novel, suitable and easily patterned materials for use in more advanced tissue culture applications for a variety of clinically relevant cell lines showing unique responses and potentially new and wide-reaching applications

Exfoliation and Raman Spectroscopic Fingerprint of Few-Layer NiPS3 Van der Waals Crystals

The range of mechanically cleavable Van der Waals crystals covers materials with diverse physical and chemical properties. However, very few of these materials exhibit magnetism or magnetic order, and thus the provision of cleavable magnetic compounds would supply invaluable building blocks for the design of heterostructures assembled from Van der Waals crystals. Here we report the first successful isolation of monolayer and few-layer samples of the compound nickel phosphorus trisulfide (NiPS(3)) by mechanical exfoliation. This material belongs to the class of transition metal phosphorus trisulfides (MPS(3)), several of which exhibit antiferromagnetic order at low temperature, and which have not been reported in the form of ultrathin sheets so far. We establish layer numbers by optical bright field microscopy and atomic force microscopy, and perform a detailed Raman spectroscopic characterization of bilayer and thicker NiPS(3) flakes. Raman spectral features are strong functions of excitation wavelength and sample thickness, highlighting the important role of interlayer coupling. Furthermore, our observations provide a spectral fingerprint for distinct layer numbers, allowing us to establish a sensitive and convenient means for layer number determination