Thermoresponsive aggregation behavior of NiPAAm/glyco monomer block copolymers studied by dynamic light scattering

Block and random copolymers containing N-isopropylacrylamide and (L-D-glucofuranosyl)-6-methacrylamido units were analyzed according to their temperature dependent aggregation behavior. Whereas a 45:55 random copolymer does not exhibit any LCST behavior below 100 °C due to the incorporation of the hydrophilic glyco monomer units, the phase transition could be retained in the physiological range in block copolymers even at a glyco monomer content above 55 mol%. DSL studies revealed that the aggregates of about 50 nm are stabilized above the transition temperature when the glyco monomer block dominates, whereas a glyco block molar ratio of 45% is not sufficient to prevent precipitation of the polymers as evidenced by turbidity measurements. Temperature dependent DLS studies revealed further that below the phase transition temperature an equilibrium between single macromolecules and aggregates is formed.