Novel High Performance Materials. Calixarene Derivatives Containing Protective Groups and Polymerizable Groups for Photolithography, and Calixarene Derivatives Containing Active Ester Groups for Thermal Curing of Epoxy Resins

Abstract

ABSTRACT:This paper reviews our recent studies on the syntheses and functions of novel calixarene derivatives with excellent thermal stability as high performance materials. Calixarene derivatives containing protective groups such as tert-butoxycarbonyl (t-Boc), trimethylsilyl (TMS), and cyclohexenyl (CHE) groups were successfully prepared by the reaction of certain calixarenes, p-methylcalix [6]arene (1a), p-tert-butylcalix [8]arene (1c), and Cmethylcalix [4]resorcinarene (1d) with the corresponding protecting reagents. Calixarene containing radically polymerizable groups such as methacryloyl groups and cationic polymerizable groups such as propargyl, vinyl ether groups were prepared in good yields. Calixarene derivatives containing cyclic ethers such as oxirane, oxetane, and spiro orthoesters were also prepared. Calixarene derivatives thus obtained had good film forming property and thermal stability. It was proved that the photoinduced deprotection of the calixarene derivatives containing protective groups in the presence of a photo-acid generator proceeded easily to give the corresponding calixarenes with phenol groups. Photoinitiated polymerization of the calixarenes with various polymerizable groups using suitable photoinitiators in the film state proceeded efficiently to produce crosslinked films. Furthermore, thermal curing of epoxy resins with calixarenes (1a, 1c, 1d), and calixarenes containing active ester groups using certain catalysts were studied to found that the calixarenes were useful curing agents for epoxy resins.KEY WORDS Calixarene / Thermal Stability / Protective Group / Polymerizable Group / Photoinduced Deprotection / Radical Polymerization / Cationic Polymerization / Thermal Curing / Epoxy Resin / Calixarenes are cyclic oligomers prepared 1 ordinarily from the reaction of phenols with aldehydes, and have attracted much interest in the field of host-guest chemistry. 2 Therefore, over the last 20 years, synthesis 3 of various calixarene derivatives and chemical modification 4, 5 of calixarenes have been studied in attempting to induce the targeted character. We can consider that calixarene derivatives have further advantage in synthetic organic chemistry as starting materials due to polyfunctional hydroxyl groups, which are readily modified to various functional groups. That is, in polymer synthesis, calixarene derivatives can also be used as multifunctional initiators for the synthesis of starshaped polymers. Kennedy and his co-workers 6 reported the synthesis of a star-shaped polymer with eight arms of poly(iso-butylene) using calix [8]arene derivative as an initiator. Sawamoto and his co-workers 7 succeeded in producing certain star-shaped polymer with 4-8 arms of poly(methyl methacrylate) using cal- † To whom correspondence should be addressed. ixarene derivative as initiator.Recently, it was also suggested that calixarenes have unique characteristics such as small molecular size, good film-forming properties, 8, 9 high glass transition temperature 10 (T g ), excellent thermal stabilit...

Epoxy Resins

“…Therefore, after the light Aryl diazonium tetrafluoroborates 4,4-Bis(N,N-dimethyl-N-(2-ethoxycarbonyl-1-propenyl)ammonium hexafluoro antimonate)benzophenone 244 Calixarene derivatives 245 9-Fluorenyl tetramethylene sulfonium hexafluoroantimonate 246 Cyclopentadiene-Fe-arene hexafluorophosphate 247 is switched off, a pronounced postpolymerization reaction can be monitored. Therefore, after the light Aryl diazonium tetrafluoroborates 4,4-Bis(N,N-dimethyl-N-(2-ethoxycarbonyl-1-propenyl)ammonium hexafluoro antimonate)benzophenone 244 Calixarene derivatives 245 9-Fluorenyl tetramethylene sulfonium hexafluoroantimonate 246 Cyclopentadiene-Fe-arene hexafluorophosphate 247 is switched off, a pronounced postpolymerization reaction can be monitored.…”

“…They found attention for their application as surfactants, chemoreceptors, electrochemical and optical sensors, solid-phase extraction phases, and stationary phases for chromatography. 245 The mechanism of initiation of MKEA is shown in Figure 3.20. Figure 3.18) can be protected with tert-butoxycarbonyl groups, trimethylsilyl groups, and cyclohexenyl groups, respectively.…”

Thermally Stable Nitrothiacalixarene Chromophores: Conformational Study and Aggregation Behavior

“…Heat stability is another factor regarding efficiency of dyes and explosives and calixarenes were reported to be heat stable [13]. In spite of the fact that nitrocalixarenes have higher melting points than monomer phenols, their thermal characteristics have not been explored in detail.…”

“…However, only two examples of monolayer formation by nitrocalixarene chromophores (both by Langmuir technique) have been reported so far [11,12]. Heat stability is another factor regarding efficiency of dyes and explosives and calixarenes were reported to be heat stable [13]. In spite of the fact that nitrocalixarenes have higher melting points than monomer phenols, their thermal characteristics have not been explored in detail.…”

Synthesis and characterization of photosensitive methacrylates to give heat-resistant polymers

“…They included bichromates, cinnamyl compounds, diazo compounds, azides, and acrylates, and have been referred to as five common photosensitive compounds. Among them, the polymers having acryloyloxy group (acrylate-type photopolymer [1][2][3][4][5][6][7][8]) surpassed the others in terms of the extent of utilizing fields and consumption, because of their advantages to form transparent, flexible, strong, and thick films. One of their uses is solder resist [9][10][11][12] in which the key structure is epoxyacrylate [13][14][15][16].…”