The Study Of Self-assembly Behavior Of Amphiphilic Block Copolymer PS-b-P4VP In Gas Expanded Liquids

Block copolymer dissolving in selective solvent can form micells structures with the solvent insoluble polymer block forming the micell core and solvent soluble block the corona. They can be widely used in surfactant, solubilizer, drug-delivery systems, and nanomaterial, etc.GXLs (Gas Expanded Liquids) have excellent solubility and mass transfer performance, which is a kind of new environment-friendly solvents. By adjusting the pressure of gas such as CO2content in the system, we can design many properties of liquid gas expansion liquids in advance. GXLs are intermediate in properties between normal liquids and supercritical fluids both in solvating power and in transport properties.In this paper, we use reversible addition-fragmentation chain transfer (RAFT) polymerization to gain a series molecular weight and different block ratio block copolymers (P4VP-b-PS), using gel permeation chromatography (GPC), Fourier infrared spectrum (FI-IR) and nuclear magnetic resonance hydrogen spectrum (1H NMR) on the polymer characterization. Then the self-assembly research of PS-b-P4VP was put in practice in CO2-expanded toluene (methanol). And we also study the behavior of self-assembly on the same temperature under normal pressure on the contrast. The self-assembled aggregates are studied by means of TEM.Results show that, under different pressure, different block proportion of block copolymers can self-assemble spherical, rod-shaped, cross linking, and vesicles and membrane structure in CO2-expand toluene. We can clearly see that a series of different morphologies evolution from spherical to rod to cross linking in CO2-expanded toluene or from spherical to core to shell structure to vesicle or membrane structure evolution; While in CO2-expansion methanol, self-assembling into a spherical or tubular structure.The study shows that the self-assembly copolymer in gas expand liquids have more obvious structure characteristics, that the morphologies are related to system pressure, the selectivity of solvent polarity, the block copolymer molecular weight and block length ratio. Finally, in this paper, potential application foreground about the self-assembly of copolymer in gas expand liquids is prospected.