Herein, a study on a new lower critical solution temperature (LCST) polymer in an organic solvent by an electrochemical technique has been reported. The phase-transition behavior of poly(arylene ether sulfone) (PAES) was examined on 1,2-dimethoxyethane (DME). At a temperature above the LCST point, polymer molecules aggregated to create polymer droplets. These droplets subsequently collided with an ultramicroelectrode (UME), resulting in a new form of staircase current decrease. The experimental collision frequency and collision signal were analyzed in relation to the concentration of the polymer. In addition, the degree of polymer aggregation associated with temperature change was also observed.
A diamine monomer with trifl uoromethyl groups, 3,3′-bis(trifl uoromethyl)-4,4′-diamino-1,1′-biphenyl, is synthesized from 5-bromo-2-nitrobenzotrifl uoride with two steps. The model reaction with monofunctional benzoyl chloride at room temperature gives the model compound with a quantitative yield. The results of the model reaction indicate that the amine groups have suffi cient reactivity in spite of the presence of electron-withdrawing and bulky trifl uoromethyl group at the ortho position. The monomer is polymerized with terephthaloyl chloride and isophthaloyl chloride in N,N -dimethylacetamide (DMAc) or DMAc containing LiCl using pyridine as an acid acceptor at room temperature. All synthesized polymers are somewhat crystalline and colorless. While the meta-linked polyamide ( PA2 ) shows excellent solubility in polar aprotic solvents, the para-linked one ( PA1 ) is dissolved in polar aprotic solvents containing LiCl and concentrated H 2 SO 4 . They show good thermal and thermooxidative stability as well as high melting temperatures.
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