Surface modification of different polymer fibres and membranes with poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)-co-(N-hydroxymethylacrylamide)

Temperature sensitive polymer poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide)-co-(N-hydroxymethylacrylamide ) grafted filter and membrane materials were produced and studied. Polyester and polypropylene multi-filament filter fabrics and polypropylene micro filtration membrane as well as polyethersulphone ultra filtration membrane were used as substrate materials. The surface modification of the substrates was carried out by activating the fabric surface with corona discharge treatment and polymerisation there after. The amount of the temperature sensitive polymer grafted on the substrate was determined by gravimetry and the surface morphology was analysed using SEM. The surface morphology was also analysed with FTIR-ATR spectroscopy. The amount of grafted polymer varies between 0,07 and 0,44 mg/cm2 on the polyester multi-filament filters. Based on the SEM-pictures, the grafted polymer seemed to localise mainly between the fibres, in fibre intersections and also in some occasions as spherical structures bound to the fibres. The results suggest that it is possible to produce membranes or filters in which the pore size and thus, the flow rate can be controlled by changing temperature. The studies have so far concentrated mainly on the surface modification of polyester and polypropylene multi-filament filter fabrics. However, the study will also be focused on the development of temperature sensitive functional membranes.