Feasible Fabrication of Hollow Micro-vesicles by Non-amphiphilic Macromolecules Based on Interfacial Cononsolvency

Herein we present a new perspective showing that water-soluble liquids,when added to water,undergo transient emulsification before complete dissolution.Thus,non-amphiphilic macromolecules can self-assemble at the two-miscible-phase interface when cononsolvent effect appears.A representative case shown here is that when poly(A/-isopropylacrylamide)(PNIPAm),prepared by aqueous radical polymerization,in methanol solution is added into water,the polymer chains rapidly self-assemble into hollow micro-vesicles based on the cononsolvency at water/methanol interface.This finding provides a subtle strategy to prepare hollow micro-vesicles by non-amphiphilic polymers without template participating.We proposed a new concept^interfacial cononsolvencyw to describe the formation process.Due to the easy modification process,sugar-contained PNIPAm chains are synthesized by copolymerization.As an application example,it is shown that these sugar-contained PNIPAm chains can afford MsweetH micro-vesicles(containing glucose residues).And the"sweer"micro-vesicles can well mimick the protocells which are involved in the recognition of bacteria.

HYDRATION AND PHASE SEPARATION OF TEMPERATURE-SENSITIVE WATER-SOLUBLE POLYMERS

Collapse of a poly（N-isopropylacrylamide） （PNIPAM） chain upon heating and phase diagrams of aqueous PNIPAM solutions with very fiat LCST phase separation line are theoretically studied on the basis of cooperative dehydration （simultaneous dissociation of bound water molecules in a group of correlated sequence）, and compared with the experimental observation of temperature-induced coil-globule transition by light scattering methods. The transition becomes sharper with the cooperativity parameter σ of hydration. Reentrant coil-globule-coil transition in mixed solvent of water and methanol is also studied from the viewpoint of competitive hydrogen bonds between polymer-water and polymer-methanol. The downward shift of the cloud-point curves （LCST cononsolvency） with the mole fraction of methanol due to the competition is calculated and compared with the experimental data. Aqueous solutions of hydophobically-modified PNIPAM carrying short alkyl chains at both chain ends （telechelic PNIPAM） are theoretically and experimentally studied. The LCST of these solutions is found to shift downward along the sol-gel transition curve as a result of end-chain association （association-induced phase separation）, and separate from the coil-globule transition line. Associated structures in the solution, such as flower micelles, mesoglobules and higher fractal assembly, are studied by USANS with theoretical modeling of the scattering function.