Preparation Of PEA And PEO-g-P4VP Micelles Based On The Effect Of Hydrogen Self-assembly

In the field of polymer science, we can prepare the amphiphilic micelles with different structures, via the method of self-assembly,giving them so many brilliant properties as biocompatibility, hydrophilicity and so on in the mean while. And among the micelles, polymeric hollow sopheres can be applied in broad prospects, including drug delivery and material modification. Owing to a regular cavity, the hollow sophere can coat a lot of drugs or hydrophobic polymer. Nowadays, the nanoscale hollow spheres prepared via the method of non-covalently connected micelles(NCCM) have been proved to be simple and operable. Besides, to get series of hollow spheres with different sizes, we can choose to change the amount of the crosslinkers or the molar ratio of polymer. And among the systems of non-covalently connected micelles, the system via hydrogen bonding tends to form more stable micelles. It can be explained in this way: first, when compared with the system using other driving force, the effect of hydrogen bonding is stronger with well-defined structures; second, the hollow sopheres via hydrogen bonding can be produced without degrating the core, but changing the common solvent into the selective one. So the self-assembly system based on hydrogen bonding have great effect on both chemistry and biology.The main research of this dissertation is about how to prepare hollow spheres via hydrogen bonding, and what is the effect on them when changing the conditions like the amount of crosslinker or solvent. It can be divided into the following two parts:1. We synthesized the polystyrene with a carboxyl group(PS-COOH) at the end of the chain and linear multi-block polyether amine(PEA) first. After that, we built this NCCM system and obtained the core-shell PS/PEA micelles in water solution successfully, followed by crosslinking the shell with formaldehyde and changing the solvent to dimethylformamide(DMF) to obtain the PEA micelles. In addition, we went further and explored what can affect the micelle formation or cavitation, for example, the dropping sequence of PS and PEA, the different molar ratios of PS and PEA, the amount of formaldehyde or the different contents of DMF. The size of the micelles reduced from 98.40 nm to 75.85 nm, which proved that the shelsl of the micelles were lockde in via the test of dynamic light scattering(DLS). Also, through DLS we can see that the size of the final micelles has increased to 113.70 nm. In the exploring experiments, we knew that the size of the hollow spheres reduced significantly to 93.46 nm. And under other conditions, the appropriate increase of the amount contributes to obtaining bigger hollow spheres. But on the contray, the size will decrease if it is beyond a certain range. In all, the shape and size of the hollow spheres can be affected by the change of the preparation conditions or each componet of the system.2. We synthesized the graft copolymer PEO-g-P4 VP and then produced the PS/PEO-g-P4 VP micelles in the CH3NO2 solution under the same condition. Here we use the dibromobutane as the crosslinkers to stablize the shell. After that, we change the solvent to DMF to get the targeting product. Further more, we change the dropping sequences of PS and PEO-g-P4 VP to see what is the difference between the formation of the core-shell micelles. Later, we also use the different molar ratios of PS and PEO-g-P4 VP, change the amount of the crossliners, or choose different contents of the solvent to explore the effect on micelle formation or cavitation. Through the DLS, we obtained the nanosacle hollow sopheres with the size of 143.21 nm, the polydispersity index(PDI) of which is 0.226, indicating that it has good dispersibility. We reversed the dropping sequence to get the smaller hollow spheres with the size of 117.40 nm. Besides, the change of other conditions such as the molar ratio, the amount of dibromobutane or the DMF further validates the conclusions of the first system.