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pp.105-114
In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(δH0m, δS0m, δG0m,) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60℃, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were 7.64×10-4~9.13×10-4, 3.85×10-4~4.60×10-4, 2.00×10-4~2.39×10-4, and 1.07×10-4~1.28×10-4 mol/l, respectively. Surface tension, γCMC, of those were 33.49~36.00, 34.78~37.61, 35.49~37.61 and 38.76~55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60℃, the change of Gibbs evergy (δGm) for one methylene group (-CH2-) were -0.65RT, respectively, The minus values of enthalpy change (δHm) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (δSm) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.
