초록
1-(2-hydroxyethyl)-2-undecyl-2-imidazoline로부터 유도된 9종의 양쪽성 계면활성제에 대한 표면장력과 등전점을 일정농도의 수용액에서 비교 검토하였고, 표면장력법에 의하여 cmc를 추정하였다. 카르복시화 아미드류의 표면장력은 $4.0{\times}10^{-4}{\sim}1.0{\times}10^{-3}mol/{\ell}$ 농도범위에서 26~40dyne/cm, 술폰화 또는 황산화 이미다졸린류는 $1.5{\times}10^{-3}{\sim}2.5{\times}10^{-3}mol/{\ell}$ 농도범위에서 30~35dyne/cm, 술폰화 아미드류는 $5.8{\times}10^{-4}{\sim}8.0{\times}10^{-4}mol/{\ell}$ 농도범위에서 25~33dyne/cm이었다. 또한 등전점의 pH 범위는 카르복시화 아미드류는 pH 7.2~7.9, 술폰화 또는 황산화 이미다졸린류와 술폰화 아미드류는 pH 4.5~5.5이었다.
Nine kinds of amphoteric surfactants were derived from 1-(2-hydroxyethyl)-2-undecyl-2-imidazoline. Their surface activities including surface tension and isoelectric points were measured in aqueous solution and critical micelle concentration(cmc) was also evaluated by the measurement of surface tension. From the measurement of surface tension, carboxylated amides revealed to be 26~40dyne/cm at $4.0{\times}10^{-4}{\sim}1.0{\times}10^{-3}mol/{\ell}$, sulfonated or sulfated imidazolines, 30~35 dyne/cm at $1.5{\times}10^{-3}{\sim}2.5{\times}10^{-3}mol/{\ell}$ and sulfonated amides, 25~33 dyne/cm at $5.8{\times}10^{-4}{\sim}8.0{\times}10^{-4}mol/{\ell}$ concentration range. It was found that isoelectric points of carboxylated amides were pH 7.2~7.9 and those of sulfonated or sulfated imidazolines and sulfonated amides were pH 4.5~5.5.