The Self-assembled Micelle Of Amphiphilic Copolymer And Its Emulsion Property

In recent years, the self-assembly and the application of amphiphilic random copolymersand block copolymers have attracted extensive attention from academia and industry.Self-assembled random polymeric micelles can be used as efficient particulate emulsifiers toprepare emulsion. The self-assembled random polymeric micelles have better emulsifyingefficiency than other inorganic particulate emulsifiers. However, the study about takingself-assembled block polymeric micelles as particulate emulsifiers are still not fully. Blockpolymeric micelles have excellent emulsification performance because of their obviouscore-shell structure. The inherent structures of the emulsifiers have a remarkable influence ontheir emulsification performance. Therefore, exploring the relationship between the polymericmicelles emulsifiers’ structure and their emulsification mechanism have important academicand practical value. The whole paper includes three parts:1. The synthsis of amphiphilic block copolymer and its self-assembled micelleA block copolymer PS-b-PtBA was synthesized from styrene （St） and tert-butyl acrylate（tBA） by atomtransfer radical polymerization （ATRP） method. Two kinds of diblockcopolymers PS₁₆₉-b-P(AA0.8-co-tBA_0.2)₁₇₉and PS₁₆₉-b-PAA₁₇₉were obtained by theincomplete and complete hydrolysis of PS-b-PtBA. The self-assembly of these diblockcopolymers in selective solvents consist of N,N-dimethylformamide and water was studied byUV-Vis, TEM and DLS. Results showed that these two copolymer could self-assemble intosphere micelles with a PS core inside. The diameter of these micelles are about100nm. Theshell of PS₁₆₉-b-P(AA0.8-co-tBA_0.2)₁₇₉micelle cantain tert-butyl acrylate hydrophobic unitsand PAA units, while there are only PAA chains on the outside of PS₁₆₉-b-PAA₁₇₉micelle.As aresult, the micelle prepared by PS₁₆₉-b-PAA₁₇₉was more sensitive to the changes of pH andmore hydrophilic than PS₁₆₉-b-P(AA0.8-co-tBA_0.2)₁₇₉.2. The emulsification properties of amphiphilic block copolymer self-assembled micellesThe micelles prepared by amphiphilic block copolymer PS₁₆₉-b-P(AA0.8-co-tBA_0.2)₁₇₉and PS₁₆₉-b-PAA₁₇₉were used as particulate emulsifiers.The emulsifying performance in response to micellar concentration, pH, salinity werestudied to understand the relationship between the polymeric micelles emulsifiers’ structureand their emulsification performance.The emulsifying characteristics demonstrated that:1)Stable emulsion could be prepared by two kinds of block polymer micelles at very lowconcentration.2) The emulsifying performance of the micelles could be enhanced by theaddition of salt.3) The phase inversion of emulsion prepared by PS₁₆₉-b-P(AA0.8-co-tBA_0.2)₁₇₉ micelles happened with pH increasing; When pH>4, stable emulsion could not be prepared byPS₁₆₉-b-PAA₁₇₉micelles4) Structure and hydrophilic-hydrophobic property of the micellesaborbing on the oil water interface would be changed by adding NaOH and HCl aqeoues,alternately. Therefore, the demulsification or phase inversion of emulsion would happen.5)The SEM image showed that there were many spherical micelles adsorbing on the oil-waterinterface and the micelle diameter inceased which attribute to swell of the micelles.3. Structure and emulsification performance of PSMVM self-assembled micellesA photosensitive amphiphilic copolymerpoly-（styrene-alt-maleicanhydride）-co-poly（7-（4-vinylbenzyloxyl）-4-methylcoumarin-alt-maleic anhydride）（PSMVM） could self-assemble into stable spherical micelles in the selectivesolvent N,N-dimethylformamide（DMF）/H2O. PSMVM micelles with variousphoto-crosslinking degrees and the swelling degree of the micelles could be controlled bychanging irradiation time and the pH value of the micellar solution. This research focuses onthe influence of the photo-crosslinking degree and the swelling degree on the micellarstructure and their emulsificaion performance. The results indicated that: The self-assembledpolymeric micelles with moderately swollen structure have better emulsifying efficiency andstability; The emulsion stablized by micelles with high photo-crosslinking degrees waspH-responsive.