微乳法合成磷酸钙纳米纤维及其机理探讨

Synthesis and study of calcium phosphate nanowires in microemulsion

分别以非离子表面活性剂(C12E8) 和阳离子表面活性剂(CTAB) 为模板剂, 在反微乳体系中制备了磷酸钙纳米纤维. 在水/C12E8/环己烷体系中纤维长约为325 nm, 宽约为13 nm, 为无定形态; 在水/CTAB/环己烷体系中纳米纤维的长度>500 nm, 宽度约为14 nm, 结晶较完全. 两种表面活性剂的作用机理完全不同: 在非离子表面活性剂体系中, 表面活性剂主要起到“微反应器”的作用; 而在阳离子表面活性剂中, 表面活性剂主要起到“生长引导剂”作用.

Calcium phosphate nanowires could be obtained in the reverse microemulsions of nonionic surfactant and ionic surfactant. Amorphous calcium phosphate nanowires with 325 nm in length and 13 nm in width could be prepared in water/C12E8 (polyethylene glycol alkyl ethers)/cyclohexane system while well-crystallized calcium phosphate with 500 nm in length and 14 nm in width could be prepared in the system of water/CTAB (cetyltrimethy lammonium bromide)/cyclohexane. However, the mechanism of the growth of crystal in these two kinds of system was entirely different. C12E8 in reverse microemlusion played a role of microreactor. With the assistance of CTAB, well-crystallized calcium phosphate nanowires could be obtained, in which surfactant CTAB acted as guiding the growth direction, but not serving as microreactors.