Synthesis And Solution Self-assembly Of Amphiphilic Linear Block Copolymers

There are great amount of research achievements about block copolymer self-assembly have been obtained for the past years. However establish a general concept to investigate the self-assembly process of triblock copolymers still remained as a challenging problem. Particularly, the self-assembly of linear triblock copolymer in solution has not been involved in deep. In this work we have synthesized a series of diblock and triblock copolymers by using ATRP and RAFT. Novel and controllable aggregation structure of several group of linear tribolock copolymers were prepared during hierarchical self-assembly process in solution. Meanwhile the preparation of functional templates based on these ordered self-assembly structure and building the nanostructure of conducting polymers in these templates were preliminarily attempted. The concrete research content of this paper lies in the following aspects:1) Two group of amphiphilic diblock copolymers PEO45-b-PtBAx(x=28,35,53) and PEO113-b-PSx(x=72,82,100) were synthesized by ATRP.PEO45-b-PtBAx(x=28,35,53) had a narrow molecular weight distributions (Mw/Mn?1.07). Influence of feed ratio to the control of the structure, molecular weight and molecular weight distributions were discussed. When the feed ratio of tBA to PEO-Br was low, the structure and the molecular weight of copolymers could be controlled accurately. By contrast, the molecular weight distribution of PEO113-6-PSx(x=72,82,100), by contrast, were slightly wider (Mw/Mn?1.17). And the results of regulate the structure of products were not satisfactory.2) Two group of amphiphilic diblock copolymers PtBA145-b-PSx(x=270,200) and PnBA28-b-PSx(xc=21,37,51,75) were synthesized by RAFT. Products with relatively narrow molecular weight distributions (Mw/Mn?1.22) were obtained. The lower molar ratio of macro chain transfer agent to second monomer (PS), the bigger amount of St in feed and the longer reaction time were beneficial to enlarge the polymerization degree of St block.3) A group of ABC triblock terpolymers PEO45-b-PtBA53-b-PSx (x=42,84,102,165) were synthesized by ATRP. In two-step hierarchical self-assembly, control of secondary self-assembly structure of triblock terpolymer PEO45-6-PtBA53-b-PSx was realized easily just by changing the length of core forming PS block. During the process the micelle structure of PEO45-b-PtBA53-b-PSx changed from spherical to cylindrical and finally entangled to raspberry like structure. Micelles with uniform diameter were obtained. Size distributions of samples after self-assembly were narrow, except PEO45-b-PtBA53-b-PS165; in the self-assembly process of one-step dialysis, we obtained vesicular micelles with distinct vesicle walls had uniform thickness.4) A group of ABC triblock terpolymers PtBA145-b-PS270-b-P2VPx(x=215,70) were synthesized by RAFT. The two-step hierarchical self-assembly was carried out to investigate the self-assembly behaviors of block copolymers in solution. For PtBA145-b-PS27o-b-P2VP215, the different methods were used in the first step of self-assembly. This caused the difference of solution condition and give rise to the discrepancy of aggregation morphology of samples. With the increase of methanol in solution the well dispersed spherical micelles, densely dispersed core-compartmentalized spherical micelles and "patchy" MCMs were obtained respectively. In the corresponding second self-assembly process, there appeared the micellar strings or cylindrical micelles formed by the adherence of the micelles mentioned above. The results of the hierarchical self-assembly of PtBA145-b-PS270-b-P2VP70showed that, the shorter length of shell forming block caused the dispersity of micelles increased and slight adherence between the micelles. The length of cylindrical micelles obtained in second self-assembly process of PtBA145-b-PS270-b-P2VP70were increased in comparison with PtBA145-b-PS270-b-P2VP215.5) PnBA28-b-PS37-b-P2VP73was synthesized successfully by RAFT. Its self-assembly behaviors of in solution was investigated by two-step hierarchical self-assembly. By choosing the non solvent of PnBA and PS in the first step, the patchy micelles with the compound core of this two blocks and the shell of P2VP were obtained. In the second step, the MCMs formed by futhur aggregation of these patchy micelles were prepared. When the concentration of fist self-assembly solution was2mg/mL, the segmented cylindrical MCMs with distinguished phase separation structure were obtained by means of "effective collision" between cores of neighboring or linked micelles for the reason that the concentration of PnBA28-b-PS37-b-P2VP73exceeded its cmc value. The multiphased and multicomponent cylindrical polymer micelles were formed by a simple way.6)?Block copolymer templates were prepared by hydrolysis of PEO45-b-PtBA35and PEO45-b-PtBA53-b-PS165. PEO45-b-PAA35, the hydrolyzed PEO45-b-PrBA35, was used to Psynthesize the micro/nano conducting polymer PAni. The influence of the adding amount of monomer at constant template content to the morphology and size of PAni grown in block copolymer templates was observed and verified that the adding amount of monomers should not be so high to obtain fibrous PAni.?Cylindrical and Fibrous PBZ were prepared in the templates of V2O5lamella. The results showed that the composite materials of PBZ/V2O5were synthesized by using emulsion polymerization at different molar ratio of PBZ to V2O5. The morphology of PBZ/V2O5composite materials changed from short micro-rods to long and thin micro fibers. Adding V2O5was useful to increasing the crystalinity, thermal stability and electrochemical activity of PBZ.