树枝状聚(醚-酰胺)基胶束的制备及其形貌研究

采用ε-己内酯(CL)开环聚合的方法首先合成树枝状聚(醚-酰胺)基(DPEA)星形聚合物star-PCL,再与异氰酸基封端的PEG(PEG-NCO)偶合制备了两亲性树枝状聚(醚-酰胺)基星形嵌段聚合物star-PCL-b-PEG.利用FT-IR、1H-NMR和GPC分析测试手段对star-PCL-b-PEG的结构进行了表征.通过滴加选择性溶剂的方法,制备了star-PCL-b-PEG以水为介质的类似"平头"聚集体胶束溶液.采用荧光光谱法测得star-PCL-b-PEG水溶液的临界胶束浓度(CMC)为1.623mg/L;采用激光光散射仪测得其在浓度0.15mg/mL和0.5mg/mL的流体力学半径分别为86.2nm和224.6nm,其多分散指数分别为0.115和0.197.透射电镜(TEM)观察发现胶束的形貌受共溶剂的特性,初始聚合物浓度,水含量等因素的影响.

PREPARATION AND MORPHOLOGIES OF MICELLE-LIKE AGGREGATES BASED ON DENDRITIC POLY(ETHER-AMIDE)

An amphiphilic star block copolymer (star-PCL-b-PEG) based on dendritic poly(ether-amide)(DPEA) was prepared through ring opening polymerization of ε-caprolactone (CL) with a DPEA-OH dendrimer as an initiator,then coupling with isocyanate terminated linear polyethylene glycol(PEG-NCO).The molecular structure was verified by FT-IR, ~1H-NMR and GPC.The polymer could form micelle-like nanoparticles due to its amphiphilic characteristics.The aggregates of star-PCL-b-PEG in aqueous media were fabricated by dropping deionized water into block copolymer solutions in common solvents.The micellar characteristics of star-PCL-b-PEG in water were similar to those of "crew-cut" aggregates. The star-PCL-b-PEG block copolymer was investigated by fluorescence spectroscopy,dynamic light scattering(DLS) and transmission electron microscopy(TEM).The critical micelle concentration (CMC) was determined by a fluorescence technique to be 1.623 mg/L.The hydrodynamic radius of micelles was measured to be 86.2 nm or 224.6 nm at different concentrations by DLS,and the polydispersity index(PDI) was estimated to be 0.115 and 0.197,respectively,showing that the particle size was relatively widely distributed at the higher concentration.As the concentration of copolymer increased,the more hydrophobic PCL segments easily aggregated with each other due to the hydrophobic interaction.Therefore,the polymer particles were formed from a lot of molecules.The morphology of star-PCL-b-PEG "crew-cut" aggregates was studied directly by TEM,and various morphologies of crew-cut micelle-like aggregates were observed under various conditions by changing the nature of common solvents,the initial copolymer concentration and the water content.The multiple morphologies,including spheres,robs and vesicles were obtained.It was found that spheres and robs were obtained from the star-PCL-b-PEG solutions with THF as the common solvent, while vesicles were obtained from the copolymer solutions with DMF as the common solvent.