Photo-dimerization characteristics of coumarin pendants within amphiphilic random copolymer micelles

The photo-dimerization characteristics of coumarin pendants within amphiphilic random copolymer micelles in aqueous solution was comprehensively investigated using various selected wavelength light in the UV-Vis-NIR region.The time-dependent photo-dimerization degree(PD) changes in the photo-dimerization experiments showed saturating behaviors with intensity-independent of PDmax values at 28%,44%,92%,85%,36%,35%,32% and 31% for 254,288,320,360,400,500,650 and 900 nm irradiations,respectively.The irradiation experiments at 254 and 288 nm announced the occurring of an asymmetric equilibrium of photo-dimerization and photo-cleavage at the used conditions.Both the alternative irradiation cycles of 360 and 254 nm,650 and 254 nm showed a partially,but evidently reversible photo-dimerization tendency.