Kanji Suyama

Photo-induced polarity alteration and photodegradation behavior of O-acryloyl acetophenone oxime and phenyl vinyl ketone copolymers

Photochemical reactions of copolymers of O-acryloyl acetophenone oxime (AAPO) and phenyl vinyl ketone (PVK) in the solid phase were investigated. The decrease of molecular weight of these copolymers in the photolysis was limited compared to that of PVK homopolymer. Results of IR and elemental analyses showed that pendant acyloxyimino (AOI) groups were phototransformed into the pendant amino groups. These behavior suggests that PVK units in this copolymer worked as a sensitizer for the photolysis of AOI groups. The energy transfer from PVK units to AOI groups was confirmed to proceed via an excited triplet state by the quenching study of phosphorescence of a PVK homopolymer by a model compound, O-cyclohexanecarbonyl acetophenone oxime. Dissolution alteration of AAPO copolymers before and after irradiation was also investigated.

Photo-initiated thermal crosslinking of copolymers bearing pendant base generating groups

The solubility change of copolymers bearing photobase generating groups on irradiation and post-exposure bake (PEB) in the presence of benzophenone groups was investigated. Pendant amino groups were obtained from the copolymers of acetophenone O-acryloyloxime (AAPO) on irradiation followed by hydrolysis. The photolysis of acyloxyimino (AOI) groups in AAPO was sensitized by benzophenone or copolymerized 4-acryloyloxybenzophenone (ABP). Although irradiated films of copolymers of AAPO and styrene containing benzophenone were soluble in tetrahydrofuran (THF), they turned insoluble by PEB. When benzophenone unit was incorporated into polymers as ABP, films turned insoluble only by irradiation, and degree of the insolubilization was enhanced by PEB. However, although copolymers of ABP and styrene turned insoluble on irradiation, the enhancement by PEB was not observed. From these results, it is clear that amino groups obtained by photo-transformation of AOI groups were effective for their post-thermal crosslinking, and that benzophenone groups were necessary for their photo-crosslinking. The role of amino groups on the thermal insolubilization was examined in detail, and we considered that the insolubilization was induced by interaction between resulting amino groups by hydrogen bonding. Copyright

Image formation by dyeing of copolymers bearing photogenerated acid and base groups with dye bath containing acid and basic dyes

Copolymers bearing photoacid generating groups and/or photobase generating groups were dyed after UV irradiation with a dye bath containing both an acid dye and a basic dye. Acetophenone O-acryloyloxime (AAPO) was used as a monomer bearing acyloxyimino (AOI) group that generates a primary amino group upon irradiation, which is followed by hydrolysis. Phenacylsulfonylstyrene (PSSt) and 1,2,3,4-tetrahydronaphthylideneamino p-styrenesulfonate (NISS) were chosen as monomers having β-keto sulfone (β-KS) and iminosulfonate (IS) groups, respectively, which yielded acid groups when irradiated. Copolymers of AAPO and methyl methacrylate (MMA) were dyed with only the acid dye, and those of PSSt or NISS were dyed with only the basic dye after irradiation. AAPO-PSSt-MMA films became dyeable with the acid dye when irradiated for a short time and with the basic dye with further irradiation. However, AAPO-NISS-MMA copolymers showed the reverse dyeing behavior. IR spectra revealed that AOI groups were photochemically decomposed prior to the β-KS groups for AAPO-PSSt-MMA, and AOI and IS groups decomposed simultaneously for AAPO-NISS-MMA. These results suggested the possibility of adsorption of different ionic dyes on the films by a change of irradiation time; in fact, color patterns could be obtained in a single staining process using the dye bath.

Effects of crosslinking by quinones on dyeing of irradiated films of copolymers bearing photobase generating groups

Films of copolymers of methyl methacrylate and O-acryloyl acetophenone oxime (AAPO), which is a monomer bearing photobase generating groups, were UV-irradiated and dyed in the presence ofp -benzoquinone or 1,4-naphthoquinone. Acyloxyimino groups in AAPO units were transformed into pendant amino groups on irradiation, and films became well dyeable with an acid dye. The quinones in the films caused crosslinking, which reduced the damage of the films during the dyeing processes compared to those without quinones. Sublimed p-benzoquinone was also introduced into heated films after irradiation, which resulted in the success of lowering the surface roughness of the films during the dyeing processes.

Novel photolabile crosslinkers based on O-acyloxime moiety

Controlled decrosslinking is an attractive technique in the fields of functional materials and polymer recycling. Photo-triggered decrosslinking is especially advantageous for easy remote activation and spatiotemporal control. However, only a few photolabile units have been used for the cleavage in crosslinkers. Herein, 1,4-diacetylbenzene 1,4-bis(O-methacryloyl)dioxime and 1,3,5-triacetylbenzene 1,3,5-tris(O-methacryloyl)trioxime are proposed as novel crosslinkers. They have a benzene ring bearing two or three arms in which O-acyloxime moiety is introduced as a novel type of photolabile unit. These crosslinkers were prepared from aromatic ketones in two steps. Photopolymerization of methyl acrylate and the crosslinkers was performed using diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide as a photoinitiator and UV light above 310 nm. Obtained polymer films were crosslinked and insoluble in tetrahydrofuran (THF). These films were further irradiated at 254 nm of light. The photolysis of O-acyloxime units in these crosslinkers were confirmed by UV and IR spectral measurements. The precedence of decrosslinking on 254 nm irradiation was evidenced by the decrease in thickness of the films after soaking in THF. Soluble fraction of the decrosslinked polymers were subjected to size exclusion chromatography, and their molecular weights were found to be similar to that obtained by photopolymerized film in the absence of the crosslinker. These results demonstrated that the proposed compounds are potential candidates for novel photolabile crosslinkers.

Photo-transformation of pendant acyloxyimino groups into vinylidene-type double bonds in copolymers of O-methacryloyl acetophenone oxime and styrene: structural analysis by 1H-NMR and 13C-NMR

The structural changes in copolymers of O-methacryloyl acetophenone oxime and styrene upon UV irradiation were followed by NMR. After irradiation, the disappearance of pendant methyl groups and the appearance of terminal olefinic carbon were observed in 1H- and 13C-NMR spectra. These facts show that the pendant methyl groups were converted to vinylidene-type double bonds. The pendant methyl group in the photoreaction of this copolymer was proved to play a very important role.

SOLUBILITY CONTROL BY UV IRRADIATION OF A COPOLYMER HAVING BOTH PHOTOBASE GENERATING GROUPS AND PHOTOACID GENERATING GROUPS

An insoluble–soluble–insoluble contrast curve is obtained for a polymer film having both photobase and photoacid generating groups when it is developed using a polar solvent; the base groups are introduced before the acid groups.

Computer-controlled laser ablation: A novel tool for biomolecular patterning

This paper describes a novel laser-based method for preparing microchannels in a bilayer system consisting of a UV sensitive polymer, acetophenone O-acryloyloxime (AAPO), layered with bovine serum albumin (BSA); BSA acts as a common blocking agent to prevent biomolecular attachment to the unexposed regions. The focus of the paper is on the use of a computer-controlled laser ablation system comprising a research-grade inverted optical microscope, a pulsed nitrogen laser emitting at 337 nm and a programmable X-Y-Z stage. By using a 100x oil immersion objective, channels of 1micrometers width and ca. 1 mm depth can be etched into the BSA-coated polymer. The precise width of the channel can be controlled by simply adjusting both the laser power and focusing. The addition of myosin to the base of these channels provides tracks on which actin filaments can move. By adjusting the width of the tracks, it is possible to regulate the direction of motion of the actin filaments.