Branched Base‐Amplifying Oligomers Enhancing UV‐Curing of Epoxy Resins

Abstract

This paper describes the preparation and the enhancing effect on anionic UV‐curing of epoxy resins of three and four‐armed oligomers bearing 9‐fluorenylmethyl carbamate residues, which displayed the autocatalytic formation of primary amino residues triggered by a photogenerated amine. The branched oligomers were readily synthesized by the Michael addition of the corresponding polythiol with 9‐fluorenylmethyl 2‐acryloyloxyethylcarbamate, which were obtained from 9‐fluorenylmethanol and commercially available 2‐isocyanatoethyl acrylate. Films of poly(glycidyl methacrylate) and a glycidylated novolac resin doped with a photobase generator exhibited boosted photosensitivity leading to photoinsolubilization in the presence of the base‐amplifying oligomers. The more marked effect of the branched oligomers on UV‐curing of epoxy resins was demonstrated by using films of a fluid epoxy, which were converted into hard films after UV exposure and post‐exposure baking, whereas no hardening occurred in the absence of the oligomers.magnified image

Synthesis of Novel Monodispersed Dendritic Base Amplifiers to Apply to Negative-tone Photoresists

“…Gel-permiation chromatograpy analysis revealed that the base-amplifying dendrimers exhibited M w = 4.29x10 3 , M w /M n = 1.04 for BA8 and M w = 8.95x10 3 , M w /M n = 1.07 for BA16, respectively, indicating that both of the dendrimers are sufficiently monodispersed.…”

“…The photosensitivity of each film is estimated to be 90 mJ cm -2 for BA8 and 17 mJ cm -2 for BA16 in a concentration of Fmoc units of 1.0 x 10 -3 mol g -1 . We have previously reported that the three-and four-armed base amplifiers (BA3 and BA4) hardly give rise to base amplifying reaction [3] at the PEB temperature of 100 o C, exhibiting 1000 (BA3) and 1200 mJ cm -2 (BA4) in photosensitivity, while the 16-terminal hyper-branched base-amplifier (HB-BA16) [2] with wide molecular weight distribution (M w /M n > 1.5) required larger exposure dose (160 mJ cm -2 ) for the insolubilization compared with the monodispersed BA16.…”

“…The dendritic base amplifiers of BA8 and BA16, a conventional photobase generator (PBG) [1][2][3] and poly(glycidyl methacrylate) (PGMA, M w = 1.30x10 4 , M w /M n = 2.4) were dissolved in mixture solvent (chloroform: propyleneglycol methylether acetate (PGMEA) = 1:1, v/v), and spin-cast onto glass substrates. The films were exposed to 365 nm UV light, heated at 100 o C, and developed with PGMEA.…”

“…We have recently begun to synthesized novel types of dendritic base amplifiers having multiple Fmoc units at the surface of the molecules, aiming at the efficient diffusion of the catalytic amine species in photoresist films. [2,3] However, our previous works on the dendritic base-amplifiers focused on low-molecular-weight (three-or four-armed) [3] and/or polydispersed hyper-branched base amplifiers (M w /M n > 1.5) [2]. We discuss herein the synthesis of novel monodispersed (M w /M n < 1.07) dendritic base amplifiers in a convenient manner, applying to the negative-tone photoresist systems with high photosensitivity by the combination of conventional photobase generator (PBG) and epoxy resins.…”

A dismantlable photoadhesion system fabricated by an anionic UV curing of epoxy resins with a base amplifier having a disulfide bond

“…Commonly, BAs are used with PBGs, and various kinds of anionic UV curing systems having high photosensitivity have been accomplished . Among base‐reactive materials, epoxy resins are known to be used for such curing systems and the resulting cured materials have good mechanical properties .…”