Koji Arimitsu

Nonlinear organic reaction of 9-fluorenylmethyl carbamates as base amplifiers to proliferate aliphatic amines and their application to a novel photopolymer system

A novel concept of base proliferation for improving the photosensitivity of base-sensitive materials is described by presenting the autocatalytic transformation of 9-fluorenylmethyl carbamates to aliphatic amines. A 9-fluorenylmethyl carbamate, as a base amplifier, was subjected to a base-catalysed fragmentation reaction to liberate the corresponding amine, which can then act as a catalyst for decomposing parent molecules, leading to autocatalytic decomposition. Consequently, the amine is generated from an equimolar amount of the carbamate using a catalytic amount of the same amine. 1-(9-Fluorenylmethoxycarbonyl)piperidine and 1-(9-fluorenylmethoxycarbonyl)cyclohexylamine were suitable as base amplifiers because of their thermal stability under neutral conditions and high base-catalytic reactivity. On the basis of the results, 1,3-bis[1-(9-fluorenylmethoxycarbonyl)-4-piperidyl]propane and 1,6-bis[(9-fluorenylmethoxy)carbonylamino]hexane were designed as base amplifiers which liberate aliphatic diamines to crosslink poly(glycidyl methacrylate) photochemically in the presence of a photobase generator. Addition of the base amplifiers resulted in a marked improvement of the photosensitivity characteristics of the polymer by a factor of 16 and 50, respectively.

Synthesis of 9-Fluorenylmethyl Carbamates as a Base Amplifier and Their Applications to Photopolymer Systems

photogeneration, leading to the low photosensitivity. To improve the photosensitivity, we reported a novel concept of base proliferations of base-sensitive compounds referred to as base amplifiers, which display autocatalytic fragmentations to give rise to amines with a basicity strong enough to lead to the decomposition of parent molecules in a non-linear manner. [6] The preceding communication describes that a phenylsulfonylethyl carbamate as a base amplifier enhance in fact the photoinduced insolubilization of a epoxy polymer to some extent. [6] Despite of our anticipation, the photosensitivity enhancement was not so markedly. Our primary concern in this communication is with providing other basesensitive compounds as base amplifiers which are more sensitive to aliphatic amines when compared with the base amplifiers described in the preceding paper. [6] A base amplifier should fulfill the following requirements. First, it should be readily subjected to a base-catalyzed decomposition to liberate a base which is capable of catalyzing the decomposition of itself. Second, it should be thermally stable in the absence of a catalytic base at least under the reaction conditions to advance the autocatalytic decomposition and a subsequent base-catalyzed reaction. Thirdly, a liberated base should be strong enough to catalyze subsequent chemical reactions to display a non-linear chemical transformation in polymeric matrices. We designed 1-(9fluorenylmethyloxycarbonyi)piperidine (1) as an alternative base amplifier to be expected to fulfill the above requirements. The carbamate 1 was easily synthesized as thermally stable crystals by the reaction of piperidine with 9-fluorenylmethyl

Autocatalytic Decomposition of A β-Tosyloxy-Ketone Acetal as an Acid Amplifier

Abstract By the action of a small amount of an acid, 2-phenyl-2-(2-tosyloxyethyl)-1,3-dioxolane decomposed to give p-toluenesulfonic acid resulting in the proliferation of acid molecules. The decomposition manner was stepwise in solution state and autocatalytic in polymer film. The sensitivity of an acid-catalyzed photoimaging material was enhanced by 10 times upon the addition of the above compound due to the acid proliferation.

Factors affecting photosensitivity enhancement of chemically amplified photoresists by an acid amplifier

The acid proliferation reaction of tert-butyl 2-methyl-2-(tosyloxymethyl)acetoacetate to liberate the corresponding sulfonic acid by the action of a tiny amount of photogenerated acid was investigated in positive- and negative-working chemically amplified photoresists. The addition of the acetoacetate as an acid amplifier to the photoresists resulted in a marked improvement in contrast, while the level of photosensitivity enhancement was relatively small for both types of photoresists, showing that the inconspicuous enhancement of photosensitivity is due to the suppression of the diffusion of acidic species in polymer films. The marked improvement of photosensitivity was achieved by the fabrication of novel double-layered photoresists doped with the acid amplifier.

Poly[(cis-3-(ethanesulfonyloxy)-2-pinanyl methacrylate)-co-(tert-butyl methacrylate)] as an acid-amplifying photoresist

Synthesis and characteristics of novel copolymers bearing both acid amplifier and acid-sensitive units are described. The acid amplifier units in the polymer side chains were acidolytically transformed to sulfonic acid residues, leading to the deprotection of the acid-labile tert-butyl ester side chains introduced as a comonomer unit. The copolymer was 3.2 times more sensitive than poly(tert-butyl methacrylate) in the presence of a photoacid generator and, therefore, provides practical applicability for photoimaging.

Phototriggered acid proliferation to enhance photosensitivity of chemically amplified photoresists

Aiming at the development of phototriggered acid proliferatin reactions to breed photogenerated acids, 1-(o-nitrophenyl(ethylene ketal of 1-phenyl-3-tosyloxy-1-propanone (1) was synthesized. 1 was deprotected photochemically to 2-benzoylethyl tosylate to release the sulfonic acid to thermally initiate the autocatalytic decomposition of 1 to advance the acid proliferation reaction. The ketal 1 was proven to be the first photolabile acid amplifier to act as an enhancer for the generation of a photo-acid. The combination of 1 with an acid-labile polymer provided a positive-working chemically amplified photo-resist, indicating that 1 acts as a photoacid generator in a polymer film.