Photochemical properties of UV-absorbing chemicals in phase-controlled polymer microspheres

In this study, a different UV (ultra-violet) ray absorption system is presented in which butyl methoxydibenzoylmethane (BMDM, a model UV-A absorbent, 320-400 nm) is stabilized in phase-controlled poly(methyl methacrylate) (PMMA) microspheres. The photochemistry of BMDM in the microspheres was investigated considering its phase characteristics therein. Analysis by differential scanning calorimetry and X-ray diffraction showed that the BMDM in the microspheres was present in a non-crystalline state. The phase control of BMDM in the polymer microspheres has an excellent ability to protect against UV-A, whilst maintaining its photostability and thermal stability. The results obtained in this study illustrate well that the phase control of the UV absorbents in polymer microspheres is another key factor that determines their photochemistry and photostability in the final formulations.