Study On Self-assembly Of The Photo-Sensitive SMA Terpolymers

In this paper, the photo-sensitive amphiphilic terpolymers PFM5C-co-P(MA-alt-St), the photo-sensitive amphiphilic comelike terpolymers P(St/CS-alt-MAA8) and P(St/CS-alt- MAA16) were synthesized by radical solution terpolymerization, and the Self-assembly of them were researched respectively.A new photo-sensitive amphiphilic terpolymer (PFM5C-co-P(MA-alt-St)) was synthesized using radical terpolymerization of maleic anhydride (MA), styrene (St) and the macromonomer (FM5C, the methacrylate derivate) with a photo-crosslinkable cinnamate pendent. The terpolymer was characterized by GPC, FTIR and 1H-NMR. It was found that the terpolymer could self-assemble into micelles in aqueous solution, and then form photo-crosslinked micelles by the photo-dimerization of the cinnamate pendants under UV irradiation (>300 nm), then photo-crosslinked micelles can be regulated by the amidolysis reaction between succinic anhydride unit and 2-aminopyridine. Pyrene probe technique, DLS analysis and TEM images were chosen to characterize its micellar morphology transformation. The results showed that the terpolymic micelles would gain a much closer morphology and a more hydrophobic local environment after photocross-linking, and an enlarged micelle with the increasing hydrophilic enviroment after the subsequent amidolysis reaction.The photo-crosslinked PFM5C-co-P(MA-alt-St) micelles solution was obtained by the photo-dimerization of cinnamon pendent under UV irradiation (>300 nm). The sulfhydryl could be introduced into micelles by the functional amidolysis reaction between succinic anhydride unit and sulfhydryl ethylamine, which could be used as the transfer agent to synthesize graft copolymer with AIBN as the inniter. Then the micelle graft copolymer Micelle-g-PHEMA-co-PSt was synthesized and characterized by FTIR and 1H-NMR. The results of UV and DLS showed that Micelle-g-PHEMA-co-PSt could self-assemble into micelles in aqueous solution, and the average size of the micelles are larger than the PFM5C-co-P(MA-alt-St) micelles.The Coumarin-containing Styrene monomer (CS) was designed and synthesized, which could be used as the third monomer to synthesize the photo sensitive amphiphilic alternating SMA terpolymer poly(styrene/coumarin-containing styrene-alt-maleic anhydride) (P(St/CS-alt-MA)) via the free radical copolymerization. Then the new photo sensitive amphiphilic comblike terpolymer (P(St/CS-alt-MAA8) or P(St/CS-alt-MAA16)) with long alkyl side chains was obtained by the functional amidolysis reaction between succinic anhydride unit and hexadecylamine or octylamin. These amphiphilic terpolymers were characterized by GPC, FTIR and 1H-NMR. The comblike polymer P(St/CS-alt-MAA8) could aggregate by the photo-dimerization of the coumarin pendants under UV irradiation (>300 nm), and form nanoscale micelles by self-assembly in selective solvent. The micelles could be modified by the ionization of carboxylic acid groups with NaOH. Pyrene loading experiment and DLS showed that the micelle diameter and the loading capacity of precrosslinked polymer are bigger than non-crosslinked polymer. Micelles reformed after ionization, which made the hydrophobic area closer and the micelle diameter smaller, while the loading capacity also increased.The comblike terpolymer P(St/CS-alt-MAA16) could self-assembly into reverse micelles in selective solvents, and then the micelles could be fixed by the photo-dimerization of the coumarin pendants under UV irradiation (>300 nm). Congo red loading experiment showned that the comblike polymer can be a single-molecule micelle in CHCl3 and the loading capacity of single-molecule micelles is as well as the multi-molecular micelles. The loading capacity of partly photo-crosslinked micelles was bigger than full photo-crsslinked micelles in CHCl3, which proved that the hydrophiphilic demains of partly photo-crosslinked micelles were more continuous than full photo-crsslinked micelles.