The ring-expansion reaction of equimolar cyclic dithioester 1 with 3-phenoxypropyrene sulfide (PPS) (cyclic dithioester 1/PPS ) 1/2) was examined in the presence of TBAC as a catalyst in NMP for 24 h. It was found that intermolecular ester-exchange reaction occurred during the insertion reaction of PPS into cyclic dithioesters, and cyclic polymers with M ns ) 3600-8900 were obtained in 80-96% yields. The structures of the obtained cyclic polymers were confirmed by the 1 H NMR, 13 C NMR IR, and MALDI TOF-MS spectroscopy. The continuous insertion reaction of excess PPS into cyclic dithioester (cyclic dithioester 1/PPS ) 1 /50) was also examined, and it was found that the insertion reaction proceeded quantitatively to afford the corresponding cyclic polysulfide with M n ) 42 000 and Mw/Mn ) 4.50 in a 96% yield.
Poly(ester-alt-sulfide) (polymer 1) was synthesized by the alternating copolymerization of glycidyl phenyl ether (GPE) with gamma-thiobutyrolactone (TBL) catalyzed by either quaternary onium salts or crown ether complexes. The copolymerization proceeded to produce polymer 1 with good yields in neat or in various organic solvents at 30-120 degreesC, in which quaternary onium salts having Cl- as a counteranion such as tetrabutylammonium chloride (TBAC) had higher activity than quaternary onium salts such as tetrabutylammonium bromide having Br- as a counteranion. It was also found that the alternate copolymer (polymer 1) of GPE with TBL was obtained selectively under different feed ratios of GPE and TBL, although ring-opening homopolymerizations of GPE and TBL did not proceed. Copolymerizations of various oxiranes such as butyl glycidyl ether, styrene oxide, and 1,2-hexene oxide with TBL catalyzed by TBAC also proceeded, and the corresponding poly(ester-alt-sulfide)s (polymers 2, 3, and 4) were obtained under the same conditions as for the synthesis of polymer 1.
Six trimers with biphenyl mesogenic groups and polymethylene spacers were synthesized. From these trimers and biphenol diglycidyl ether (BPGE), a new series of combined liquid crystalline polymers (LCPs) with polyether backbone were synthesized by the polyaddition with quaternary phosphonium chloride as catalyst. The effects of flexible spacer length on the phase transition and mesomorphism of the resulting trimers and combined LCPs were studied using differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction. The trimers with 1,3-propylene and 1,4-butylene spacers were absent of mesophase, and the trimers with odd-numbered spacers, 1,5-pentylene and 1,7-heptylene, were nematic. In contrast, the trimers with even-numbered spacers, 1,6-hexylene and 1,10-decylene, were smectic within very narrow temperature ranges. All the combined LCPs were thermotropically nematic, though the crystalline behavior was complex with varying sidechain spacer length. The combined LCPs with 3, 5, and 10 methylene units (n) of side-chain spacers were semicrystalline at room temperature while other polymers were glassy. The combined LCPs showed general odd-even effects of side-chain length on T CP and isotropization entropy in which the polymers with even numbers of methylene units in side-chain spacer showed higher values.
Polyesters containing donor-acceptor norbornadiene (D-A NBD) residues in the main chain were synthesized by the polyaddition of D-A NBD dicarboxylic acids, 5-(4-methoxyphenyl)-1,4,6,7,7pentamethyl-2,5-norbornadiene-2,3-dicarboxylic acid and 5,6-bis(4-methoxyphenyl)-7,7-dimethyl-2,5norbornadiene-2,3-dicarboxylic acid, with bis(epoxide)s. The photoisomerization of the NBD residues in the resulting polyesters proceeded smoothly to give the corresponding quadricyclane (QC) groups. The NBD residues in these polyesters showed resistivity to repeated cycles of the interconversion.
The synthesis of poly(carbonate)s with phenoxymethyl groups in their side chains by a polyaddition of bisphenol A diglycidyl ether (4a) with diphenyl carbonate (2) using quaternary onium salts or crown ether complexes as catalysts is described. When the polyaddition was performed with the catalyst containing Clas a counteranion such as tetrabutylammonium chloride, tetrabutylphosphonium chloride, or 18-crown-6/KCl without solvent at 100 °C for 48 h, the corresponding poly(carbonate) with high molecular weight (Mn ) 20 000-34 000) was successfully obtained. 1 H NMR and 13 C NMR spectra of the resulting polymer indicated that the reaction proceeded regioselectively at the epoxy groups of 4a to give the polycarbonate with pendant phenoxy groups. The polyaddition of various bis(epoxide)s with 2 also proceeded in bulk to provide the corresponding poly(carbonate)s with high molecular weight in good yield.
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