Four photoreactive coumarin derivatives were successfully synthesized from 7‐hydroxy‐coumarin and 7‐hydroxy‐4‐methylcoumarin, i.e., 7‐propionyloxy‐4‐methylcoumarin (M1), 7‐palmitoyloxy‐4‐methylcoumarin (M2), 7‐propionyloxycoumarin (M3), and 7‐palmitoy‐loxycoumarin (M4). Reversible photodimerization (350 or 300 nm) and photocleavage (254 nm) of these coumarin derivatives dispersed in poly(vinyl acetate) (PVAc) were investigated by tracing their UV absorbance variations at 310 nm. The M2 and M4 with long palmitoyl chain show much better photoreaction reversibility than M1 and M3 with short propionyl chain. Moreover, photodimerization rate (under 350 nm) of M2 is greater than 200 times of that of M1. This has been explained by the formation of suitable conformation for revers‐ible photodimerization due to the hydrophobic interactions. Photodimerization of M2 is ca. 3 times quicker than that of M4, indicating 4‐methyl substitution enhances pho‐todimerization. The influence of photodimerization wavelength (350 and 300 nm) and photosensitizer (benzophenone) have also been investigated in detail. © 1995 John Wiley & Sons. Inc.
|Number of pages||10|
|Journal||Journal of Polymer Science Part A: Polymer Chemistry|
|Publication status||Published - 1995 Nov 30|
All Science Journal Classification (ASJC) codes
- Polymers and Plastics
- Organic Chemistry
- Materials Chemistry