表面活性劑在水(shui)中隨著(zhu)濃度(du)增大， 表面(mian)上聚集的活性劑分(fen)子(zi)形(xing)(xing)成定向(xiang)排列的緊密(mi)單(dan)分(fen)子(zi)層，多余的分(fen)子(zi)在體相(xiang)內部也(ye)三三兩(liang)兩(liang)的以憎水(shui)基(ji)互相(xiang)靠攏(long)，聚集在一起形(xing)(xing)成膠(jiao)束(shu)，這開(kai)始形(xing)(xing)成膠(jiao)束(shu)的低濃度(du)稱為臨界膠(jiao)束(shu)濃度(du)。? ?

這時溶液性(xing)質與(yu)理(li)想性(xing)質發生偏離，在(zai)表面張(zhang)力對濃度繪制的(de)曲(qu)線(xian)上(shang)會出現轉(zhuan)折。繼續增(zeng)加活(huo)性(xing)劑濃度，表面張(zhang)力不再(zai)降(jiang)低，而體相中的(de)膠束不斷增(zeng)多、增(zeng)大。? ?

表(biao)面(mian)活性(xing)劑在溶液(ye)中分散，當達到一定濃(nong)度時(shi)，表(biao)面(mian)活性(xing)劑分子會(hui)從單體(ti)( 單個離子或分子) 締合成為膠(jiao)(jiao)態聚集物，形(xing)成膠(jiao)(jiao)團。溶液(ye)性(xing)質隨之發生突變，此(ci)時(shi)的濃(nong)度，即(ji)形(xing)成膠(jiao)(jiao)團時(shi)的濃(nong)度，稱為臨(lin)界膠(jiao)(jiao)團濃(nong)度(critical?micelle?concentration，簡(jian)寫為CMC) ，表(biao)面(mian)活性(xing)劑形(xing)成膠(jiao)(jiao)團的過(guo)程稱為膠(jiao)(jiao)團化作用。? ?

表(biao)面活性劑分子締合形(xing)成(cheng)膠束(shu)的低濃(nong)度。當其濃(nong)度高于CMC值(zhi)時，表(biao)面活性劑的排(pai)列(lie)成(cheng)球狀(zhuang)、棒狀(zhuang)、束(shu)狀(zhuang)、層狀(zhuang)/板(ban)狀(zhuang)等結(jie)構。 ???

增溶(rong)(rong)(rong)體(ti)系為熱力學平衡體(ti)系；CMC 越(yue)(yue)(yue)低、締合數越(yue)(yue)(yue)大，增溶(rong)(rong)(rong)量（MAC）就(jiu)越(yue)(yue)(yue)高；溫(wen) 度(du)(du)對增溶(rong)(rong)(rong)的影響(xiang)(xiang)(xiang)：溫(wen)度(du)(du)影響(xiang)(xiang)(xiang)膠束的形成，影響(xiang)(xiang)(xiang)增溶(rong)(rong)(rong)質的溶(rong)(rong)(rong)解(jie)(jie)，影響(xiang)(xiang)(xiang)表面活(huo)性劑的溶(rong)(rong)(rong)解(jie)(jie)度(du)(du)?離(li)子型(xing)表面活(huo)性劑的溶(rong)(rong)(rong)解(jie)(jie)度(du)(du)隨(sui)溫(wen)度(du)(du)增加而急劇增大這一溫(wen)度(du)(du)稱為Krafft點，Krafft點越(yue)(yue)(yue)高，其臨(lin)界膠束濃(nong)度(du)(du)越(yue)(yue)(yue)小。 ? 

對(dui)于聚(ju)(ju)氧乙烯(xi)(xi)型非離(li)子表面活性劑，溫度升高到一定(ding)程度時，溶(rong)解度急劇下降并(bing)析(xi)出(chu)，溶(rong)液(ye)出(chu)現混濁(zhuo)，這(zhe)一現象稱為起曇(tan)，此溫度稱為曇(tan)點(dian)。在聚(ju)(ju)氧乙烯(xi)(xi)鏈(lian)相(xiang)同時，碳氫(qing)鏈(lian)越長，濁(zhuo)點(dian)越低；在碳氫(qing)鏈(lian)相(xiang)同時，聚(ju)(ju)氧乙烯(xi)(xi)鏈(lian)越長則濁(zhuo)點(dian)越高。 ???

非極性有機物如(ru)苯在(zai)水中(zhong)(zhong)溶(rong)解度(du)很小,?加入油酸(suan)鈉等表面活(huo)性劑后(hou),?苯在(zai)水中(zhong)(zhong)的(de)溶(rong)解度(du)大(da)大(da)增(zeng)(zeng)加,?這稱為增(zeng)(zeng)溶(rong)作(zuo)用。 增(zeng)(zeng)溶(rong)作(zuo)用與普(pu)通的(de)溶(rong)解概念是不同(tong)(tong)的(de),?增(zeng)(zeng)溶(rong)的(de)苯不是均(jun)勻分散在(zai)水中(zhong)(zhong),?而(er)是分散在(zai)油酸(suan)根分子(zi)形成的(de)膠束(shu)中(zhong)(zhong)。經X 射線衍射證實(shi),?增(zeng)(zeng)溶(rong)后(hou)各種(zhong)膠束(shu)都有不同(tong)(tong)程度(du)的(de)增(zeng)(zeng)大(da),?而(er)整個溶(rong)液(ye)的(de)的(de)依數性變化不大(da)。