posted on 2019-03-08, 00:00authored byHirohmi Watanabe, Mariko Takahashi, Hideyuki Kihara, Masaru Yoshida
Photocurable
urushiol analogues were synthesized using eugenol
(an ingredient of clove oil) as the starting material. Photo-induced
radical polymerization with 2,2-dimethoxy-2-phenylacetophenone as
a photo-initiator took place in the film prepared from the urushiol
analogue-bearing methacryloxy groups at the ends of their side chains.
Successful polymerization was confirmed by infrared spectroscopy measurements
of the film before and after photo-irradiation. Strain-induced elastic
buckling instability for mechanical measurement tests revealed that
the Young’s moduli of the photo-irradiated samples were 4–5
times higher than the films without photo-irradiation. This was attributed
to the formation of a highly cross-linked structure through polymerization
of the methacrylic moieties and oxidative polymerization of the catechol
moieties. Photo-induced surface texturing was also performed for the
films prepared on a substrate using a photomask. Negative-tone patterns
were successfully obtained after development by soaking in cyclohexanone
over several minutes. The preparation of such patterned surfaces was
of particular relevance as the obtained surface can serve as a scaffold
for cell adhesion, protein immobilization, and the immobilization
of other chemicals with spatial disposition.