离子型表面活性剂对PS-b-PAA嵌段共聚物在DMF/H_2O中自组装形貌的影响

Effect of ionic surfactants on the morphology of PS-b-PAA block copolymers in DMF/H_2O mixtures

以丙三醇为基体,合成了三(2-(N,N-二甲基十六烷基氯化铵)乙酸)丙三醇酯(S1)和(2-十六烷基羧酸酯)丙二羧酸钠(S2)两种结构相近但极性相反的表面活性剂,研究它们对聚苯乙烯-b-丙烯酸(PS-b-PAA)在DMF/H2O混合体系中自组装行为的影响。结果表明,2种表面活性剂均使PS-b-PAA的球形胶束发生了改变,但二者作用的结果不同。随表面活性剂溶液浓度的增大,S1/PS-b-PAA体系的胶束形貌发生由短棒向长棒再到囊泡的转变,形成的棒状胶束长度越来越长(由251 nm→418 nm→1 280 nm);S2/PS-b-PAA体系,胶束形貌发生由球形→较大球形和部分S2的小球形共存→片层和较大球形共存的转变,胶束尺寸逐渐增大(由134 nm→188 nm→1 597 nm)。电离后,电荷数量及其烷基链与嵌段共聚物相互作用的差异是导致2种表面活性剂对胶束形貌产生不同影响的原因。

Two glycerol-based surfactants which had similar structures but oPPosite charge were synthe-sized. The cationic surfactant was N,N-dimethyl-N-（2-oxo-2-（（16,16,26,26-tetramethyl-18,24-dioxo-19 ,23-dioxa-16 ,26-diazadotetracontan-16 ,26-diium-21-yl ）oxy ）ethyl ）hePtadecan-1-aminium chloride （ named S1 ）,whereas the anionic surfactant was 2-（ Palmitoyloxy ）malonate disodium salt（ named S2 ）. The influences of S1 and S2 addition on the self-assembly behavior of Polystyrene-b-Poly（ acrylic acid） （ PS-b-PAA）in DMF/H2 O mixtures were investigated. The result showed that both cationic and anionic surfactants can interact with the coPolymer,inducing the morPhological transition. As the concentrations of S1 increased,the aggregates morPhology changed from short rods to longer rods,and from longer rods to vesicles,whereas the morPhology aPPeared bigger sPherical micelles and smaller sPhere of S2 coexist then bigger sPherical micelles and lamellae coexist as the S2 rePlaced S1 . And the lengths of rod-like micelles and vesicles in diameter of S1/PS-b-PAA were statistic by i-TEM,which demonstrated that the sizes of rod-like micelles and vesicles lager at higher S1contents（from 251 nm→418 nm→1 280 nm）. The aver-age Particle sizes of S2/PS-b-PAA measured by dynamic light scattering technology,the Particle size of micelles increased with the concentrations of S2 increased（ from 134 nm→188 nm→1 597 nm）. This re-sulted from the difference between the interactions of their alkyl chains with PS-b-PAA and the difference between the amounts of their ionic charge.