Synthesis and liquid crystalline properties of new twin diglycidyl ethers based on azomethine groups cured by aromatic diamines
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Date
2010
Authors
Rajasingam, Ratnamalar
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Abstract
Two bisphenols containing azomethine groups namely, 3,3'-dimethoxy-4,4'dihydroxy-
N-benzylidene-o-tolidine (I) and 4,4' -dihydroxy-N-benzylidene-o-tolidine
(II) were synthesized by reaction of o-tolidine with vanillin and phydroxybenzaldehyde.
Subsequent reaction with epicholorohydrin in the presence of
a catalyst called tetrahexylammonium bromide (THABr) to produce new twin liquid
crystalline diglycidyl ethers namely, 3,3 '-dimethoxy-4,4 '-di(2,3-epoxypropoxy)-Nbenzylidene-
o-tolidine (III) and 4,4' -di(2,3-epoxypropoxy)-N-benzylidene-o-tolidine
(IV). The chemical structures were confirmed by FT-IR, 1H-NMR, 13C-NMR, UVVis
spectroscopy and elemental analysis (CHN). Curing of III and IV were then
carried out with two different aromatic diamines namely, 4,4'-diaminodiphenyl
sulfone (DDS) and p-phenylene diamine (PPDA) in the ratio of diglycidyl ether I
diamine 1:1, 2:1, 3:1 and 4:1. The occurrence of curing reaction was confirmed by
FT-IR spectroscopy. Degree of crystallinity, liquid crystal behaviors as welJ as the
thermal properties of III, IV and the cured new twin diglycidyl ethers were studied
by wide-angle X-ray diffractometer (WAXD), differential scanning calorimetry
(DSC), polarized optical microscope (POM), and thermogravimetric analysis (TGA),
respectively. Mechanical properties of the cured new twin diglycidyl ethers were also
studied via adhesion, hardness, flexibility, and impact tests.