Author(s): Faria, Jaime Moreira Machado
Date: 2016
Persistent ID: http://hdl.handle.net/10362/21758
Origin: Repositório Institucional da UNL
Subject(s): PVP; PNIPAAm; Composites; Microgels; Colloidal electrospinning; Fibers; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais
Electrospinning technique has proven to be a suitable approach to produce high surface area to volume ratio polymeric membranes with tailored architecture. To increase its functionality, a straightforward strategy can be the confinement of externally stimuli responsive systems, such as microgels. This combination enables the production of multifunctional composite systems. This thesis reports the development of composite fibres through colloidal electrospinning constituted by polyvinylpyrrolidone (PVP) containing poly(N-isopropylacrylamide) (PNIPAAm) microgels. The focus of the dissertation deals with the optimization of the fibre precursor, PVP. In the first stage, an extensive study towards the production of PVP non-woven mats with high surface area to volume ratio was performed. The obtained non-woven mats were crosslinked using UV irradiation, a green and cost-effective technique, to ensure structure stability in the presence of a solvent (prevent dissolution). Non-woven mats were further characterized in terms of morphological, mechanical and swelling properties. In addition, the fibre precursor, PVP, was analysed through a process-dependent comparative study: non-woven mats vs. films. The most suitable electrospinning parameters were further used to confine PNIPAAm thermoresponsive microgels in PVP fibres through colloidal electrospinning. The system was further crosslinked and fully characterized to obtain a multiresponsive composite system. This versatile approach is a starting point to design and produce composite multifunctional systems that could be tailored for a wide range of applications.
