Synthesis and Characterization of Block Copolymer PNIPAM-b-PDMAEMA Using RAFT and Study of Its Responsivity toward pH and Temperature Rida Hasna Fadhilah, Ivandini Tribidasari Anggraningrum, Noverra Mardhatillah Nizardo
Universitas Indonesia
Abstract
Stimuli responsive block copolymers of poly(N-isopropylacrylamide)-block-poly(2-dimethylamino)ethyl methacrylate) (PNIPAM-b-PDMAEMA) were successfully synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization by varying the chain length of the second block (PDMAEMA), and studied its effect on the phase transition temperature (Tc) as well as pH- and thermo-responsive behavior. Characterization using 1H-NMR and FTIR indicate the product of block copolymers PNIPAM21-b-PDMAEMA2 and PNIPAM21-b-PDMAEMA7 were successfully formed. Unusual result detected by GPC analysis which showed that the GPC traces of block copolymers shifted toward lower molecular weight in comparison with macro-CTA. Thermo- and pH-responsive behavior of block copolymers was investigated in phosphate buffer of varying pH and temperature using UV-Visible spectrophotometer. The results showed that the hydrophilic carboxyl end group and the hydrophobic dodecyl end group had an effect on the resulting Tc. There was an increasing trend of Tc when pH increased from pH 5 to pH 7.4 while Tc was constant at pH 7.4 and 9 due to the effect of pH-dependent PNIPAM and PDMAEMA blocks. Diameter particle of block copolymers PNIPAM21-b-PDMAEMA2 in pH 5 and 9 increased along with heating based on particle size analyzer (PSA) results. Moreover, the synthesized block copolymers open up new potential in drug delivery system.
