LASER-INDUCED PHASE-TRANSITION IN AQUEOUS-SOLUTIONS OF HYDROPHOBICALLY-MODIFIED POLY(N-ISOPROPYLACRYLAMIDE)

Phase transitions of amphiphilic copolymer solutions can be achieved b y irradiating aqueous solutions of this polymer with an IR-laser beam. As a result, a single microparticle up to 15 mu m is formed, whereas thermal heating of the solution results in submicrometer particles. Bo th the photo-thermal effect (due to absorption of 1064 nm by the H2O o vertone) and the radiation force cause the unusual large particle form ation (up to 15 Gem). Furthermore, the present study shows that the co nformational distribution and associations of polymers in solution can be controlled with the radiation force of a focused laser beam.