혼합계면활성제들의 임계미셀농도(CMC)값과 그 용액에서 4-ethylaniline의 가용화상수(Ks) 값을 UV-Vis법으로 측정하고 분석하였다. 그 결과 TTAB/LSB와 TTAB/TX-100 혼합계면활성제들은 이상적 혼합 미셀화로부터 크게 벗어나지 않았다. 그러나 SDS/LSB와 SDS/TX-100 혼합시스템은 큰 음의 벗어남을 보였다. 이러한 차이는 미셀 상에서 두 성분들의 상호작용의 세기가 서로 다름으로 나타났으며, 이것들이 4-ethylaniline의 가용화에 크게 영향을 미침을 알 수 있었다. 순수 계면활성제 중에 음이온 계면활성제인 SDS가 다른 계면활성제보다 더 큰 Ks값을 보였으며, Ks값은 SDS≫TTAB≧ LSB>TX-100 순으로 감소하였다. 그리고 혼합계면활성제에 의한 Ks값은 그것을 구성하는 순수 계면활성제의 Ks값보다 더욱 큰 값을 나타내었다.

양쪽성 계면활성제인 dodecyldimethyl(3-sulfopropyl)ammonium hydroxide(LSB, CH3(CH2)11N+(CH3)2(CH2)3SO3-)와 LSB/Tween-20, LSB/Tween-40, LSB/Tween-80 및 LSB/DTAB, LSB/TTAB, LSB/CTAB 혼합계면활성제의 임계미셀농도(CMC)값을 284 K에서 312 K의 온도범위에서 UV/Vis 분광광도법으로 측정하였다. 열역학적 연구를 위해 온도의 변화가 미셀화에 어떤 영향을 미치는지를 분석하였다. 계산한 결과 측정범위 내에서 미셀화에 따른 깁스 자유에너지값은 측정범위 내에서 모두 음의 값을 나타내었다. 한편 엔탈피값은 Tween-20에서는 양의 값을 그리고 다른 계면활성제에서는 음의 값을 나타내었다. 엔트로피값은 측정한 온도범위 내에서 모두 양의 값을 나타내었다. 또한 모든 열역학 함수값들은 온도와 알킬-그룹의 길이에 따라 큰 변화를 보였다.

Substantial efforts have been made to manipulate ruminal environment in a hope to enhance ruminal fermentation efficiency for better ruminant productivity. Some of examples are methane inhibitors, antibiotics, microbial enzymes, fatty acids and/or lipid feeding, buffering agents, ionophores and probiotics. Of these efforts, the non-ionic surfactant (NIS) has been known for its stimulation to release enzymes from a range of anaerobic microbes. A series of studies were conducted 1) to evaluate NIS diluted with water and ethanol on in vitro ruminal fermentation and 2) to determine the influence of diluted NIS on digestibility of feedstuffs. In first experiment (Exp. 1), NIS was diluted with water or ethanol to measure its effects on in vitro microbial growth, ruminal enzyme activities and gas production by mixed ruminal microbial culture. The NIS was diluted with water or ethanol separately in a 1:5 ratio (w/v). Water and ethanol-diluted NIS with wheat flour were added with rice straw-based mixed ruminal microbial cultures at the rate of 2 ㎎ NIS/16 ㎖ McDougall buffer plus 4 ml ruminal fluid solution. The mixed ruminal microbial culture was run without any NIS addition as control. Addition of NIS either diluted with water or ethanol has significantly reduced the gas production in mixed ruminal microbial culture at 12 and 24 h of incubation. At 48 h post incubation, gas production was the highest with the addition of ethanol diluted NIS followed by water-diluted NIS and control. Carboxy methyl cellulase activity in rice straw-based mixed ruminal bacterial culture was significantly higher with the addition of ethanol-diluted NIS compared with the addition of water-diluted NIS and control at 24 and 72 h post incubation. In second in vitro experiment (Exp. 2), effects of addition of ethanol diluted NIS on dry matter (DM) digestibility of alfalfa hay, gas production, pH and cellular growth in mixed ruminal microbial culture were examined. Alfalfa hay based mixed ruminal microbial culture without any NIS addition was run as a control. The pH of mixed ruminal microbial culture was significantly lower than control at all post incubation sampling hours. In vitro DM digestibility of alfalfa hay was significantly higher with the addition of NIS compared with control. Gas production was significantly less with NIS addition compared with control at all post incubation sampling hours. Microbial growth in mixed ruminal microbial culture was significantly increased with the addition of NIS compared to control.

In general, anionic and cationic surfactants are incompatible because their mixtures form insoluble complexes. There are, however, some complexes that are soluble and behave like regular surfactants, specifically like nonionic surfactants, thus named pseudo-nonionic surfactant complexes. Pseudo-nonionic complexes are more effective and efficient than their ionic surfactant components as shown by their equilibrium and dynamic surface tensions and interfacial tensions. They pack at the interface more than their ionic components. Since, pseudo-nonionic complexes show their own characteristics, they can be treated as separate classes of surfactants distinct from ionic and nonionic surfactants. Novel cationic surfactant was synthesized, having the polyhydroxyl group at the head group. We found that aqueous mixtures of our cationic surfactant and usual anionic surfactant(SDS) could form homogeneous solutions even at high concentration. The properties of mixed surfactant solutions were measured. Foam stability, CMC(critical micelle concentration), water hardness tolerance and thickening effect were tested. The foam stability of mixed surfactants was very good and various synergy effects were observed.

The interaction between anion and zwitterionic surfactants was investigated by means of surface tension, NMR spectroscopy, and fluorescence studies. These systems are N-tetradecyloxymethyl-N,N-dimethyl betaine (C14, TDB), N-octadecyloxymethyl-N,Ndimethyl betaine (C18, ODB), and sodium dodecylethoxy sulfate (SDE). These systems show a composition dependency in micellar properties. When the molar fraction of TDB and ODB was about 0.6, the cmc values of these systems showed minima, whereas the solubilized amount of a water insoluble dye, NMR line width showed maxima. These changes comes from the intramolecular complexes formed in the mixed micelles. The complexes are due to the electrostatic interaction of oppositely charged head groups of betaine and sodium dodecylethoxy sulfate. A comparison of betaine and SDE alkyl methylene group line widths to those of n-methyl group indicates that the interior of the micelle in the restricted region is more immobile than the head group.