Enhanced Molecular Alignment in Poly-l-Lactic Acid Nanotubes Induced via Melt-Press Template-Wetting

Abstract

Molecular ordering in polymers can have a drastic effect on their properties, and can be used to induce or enhance functionality. In the case of poly-L-lactic acid (PLLA), which is a widely used polymer in biomedicine, sensors and actuators, preferential orientation of chains can lead to significantly enhanced electromechanical properties. In this context, template-wetting is a straightforward method of producing polymer nanostructures, which can lead to some degree of molecular order in the polymer. Template-wetting of PLLA has not been fully explored, especially in terms of morphological and/or structural characterisation. In this work, PLLA nanotubes are grown via a modification of the template-wetting process, referred to here as melt-press template-wetting. The nanotubes are thoroughly characterised with wide-angle X-ray diffraction, isothermal differential scanning calorimetry and polarised light optical microscopy. This characterisation indicates that the polymer chains in these PLLA nanotubes are aligned parallel to the cylindrical axis of the nanotube, which may be beneficial in certain applications.