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Surface characterization of binary graft copolymers (PP-g-DMAEMA)-g-NIPAAm and(PP-g-4VP)-g-NIPAAm by Using SEM and AFM

Abstract:

In the present work, thermal-pH dependent binary graft copolymers (PP-g-DMAEMA)-g-NIPAAm and (PP-g-4VP)- g-NIPAAm at different degree of grafting (DG, %) of N-isopropylacrylamide (NIPAAm) (DG of 30, 90, 200 and 400 %) were characterized by scanning electron microscope (SEM), atomic force microscope (AFM) and swelling studies. SEM images showed formation of NIPAAm crosslinked network at degree of grafting greater than 90 %. Also, when the graft reaction time is increased, NIPAAm crosslinking is increased. Higher NIPAAm crosslinking resulted in lower swelling ratio. In addition, the AFM technique was used in order to obtain information on the changes in surface topography and roughness under different degree of grafting. Both binary graft copolymers presented larger surface roughness than their precursor single graft copolymers, though surface roughness decreased at degree of grafting higher than 200 %. These results of SEM, AFM and swelling studies suggest that both binary graft copolymers, (PP-g-DMAEMA)-g-NIPAAm and (PP-g-4VP)-g-NIPAAm, have potential in biopplications and that a relatively lower degree of grafting around 90 % is the optimal value. © 2010 American Chemical Society.