CHEMICAL AND OPTICAL MECHANISM OF MICROPARTICLE FORMATION OF POLY(N-VINYLCARBAZOLE) IN N,N-DIMETHYLFORMAMIDE BY PHOTON PRESSURE OF A FOCUSED NEAR-INFRARED LASER-BEAM

We focus our attention to the laser-controlled association process of poly(N-vinylcarbazole) by ''pure'' photon pressure effect. A few wt % N,N-dimethylformamide solution of the polymer was irradiated with a fo cused 1064 nm laser beam of sub wattage power, and a resultant condens ation (microparticle formation) at a focal point of the microscope was initially probed by backscattering of Pie-Ne laser and later observed by transmission image of the microscope. To understand in detail the behavior of the polymer induced by the photon force, the relation betw een laser power and particle diameter, as well as repeated irradiation effect, were investigated. The laser-controlled association was succe ssfully demonstrated even for short polymer chains of about 20 mean de grees of polymerization. Fluorescence spectra and their I ise and deca y curves were measured microspectroscopically for a formed micropartic le. The results are different from those of the polymer in solution, s uggesting the association structure is characteristic of photon pressu re effect.