Abstract
Linear water-soluble stimuli-responsive double hydrophilic block copolymers, poly(N-isopropylacrylamide)-block-poly(acrylic acid) [abbreviated as PNIPAM-b-PAA (degree of polymerization (DP) of PNIPAM = 149 and DP of PAA = 46 or 85)] were synthesized using reversible addition−fragmentation chain transfer (RAFT) polymerization technique and characterized by gel-permeation chromatography (GPC) and nuclear magnetic resonance (1H NMR) spectroscopy. Turbidimetry, spectral, and scattering studies showed that block copolymers remain as molecularly dissolve in water below the lower critical solution temperature (LCST) of PNIPAM block (~32 °C). Turbidimetry results confirm the formation of aggregates with PNIPAM core and PAA as a shell in the presence of NaCl, CaCl2 and at temperatures above the LCST of PNIPAM. The cloud point temperature (TC) of both block copolymers increases with an increase in DP of PAA in neutral and basic pH and decreases at low pH. Small angle neutron scattering (SANS) data confirmed the formation of worm- or thread-like micelles in the presence of a cationic surfactant dodecyltrimethylammonium bromide (DTAB).
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