DESIGN, SYNETHESIS, DYE-LOADING AND HOST-GUEST COLORING APPLICATION OF AMPHIPHILIC HYPERBRANCHED POLY(QUATERNARY AMMONIUM SALT)S

Abstract

A novel AB2-type monomer with one azide group and two alkyne groups and two quaternary ammonium salt units was synthesized via highly efficient thiol-yne click chemistry and Menschutkin reaction.The synthetic protocol includes three steps:(1) 4-oxo-4-(prop-2-ynyloxy)butanoic acid 1 reacts with 3-(dimethylamino)-1-propanethiol via thiol-yne click chemistry to obtain intermediate 2 containing one carboxyl group and two dimethyamino groups with high yield(~97.5%),(2) esterification between carboxyl group of 2 and 2-azidoethanol to afford intermediate 3,(3) fast click-like Menschutkin quaterization of the two dimethylamino groups of 3 with propargyl bromide to give the final AB2-type monomer 4 possessing one azide group,two alkyne groups and two quaternary ammonium salt units.The monomer structure was confirmed by NMR,FT-IR and MS.The subsequent click polymerization of 4 gave rise to quaternary ammonium salt-type hyperbranched polymers.End-capping the polymers with azide-terminated alkyl long chains resulted in amphiphilic hyperbranched polymers(AHPs) with hydrophilic quaternary ammonium salt core and hydrophobic alkyl shell.The AHPs were characterized by 1H-NMR,FTIR,and gel permeation chromatography(GPC) measurements.The AHPs have number-average molecular weights(Mn) of 3800~5300 and narrow polydispersity index(PDI,1.17~1.27).The host-guest dye-encapsulation property of AHPs was investigated using congo red(CR),methyl orange(MO),methyl violet(MV),methyl blue(MB),eosin Y(EY),fluorescein sodium(FS) and rose Bengal(RB) as guests with UV-Vis spectrometer.The AHPs exhibited high capabilities to load water-soluble dyes due to their polarity difference between core and shell,and the dye-transfer percentage from water to chloroform phase reached 93%~99% for MO,MV,FS,and EY,and 71%~76% for RB and CR.The average numbers of dye molecules trapped per macromolecule achieved 0.5~0.6 for MO,MV,FS,EY and RB,and 4.8 for RB.The polymer-dye complexes were used as additives for coloring common polymers such as SBS and PMMA.The complexes showed excellent dyeing and dispersing effects for both SBS and PMMA membranes because the long aliphatic chains of AHPs could be well compatible with polymer matrix,and the membranes displayed much better transparency as compared with the control samples of dye-coloring resins without AHPs.The color of the membranes with AHPs is very uniform and stable,almost without any dyes releasing from the membranes into water after being immersed in water for a long time(up to several weeks).On the contrary,the control samples released dyes seriously when they are immersed in water for a short time.Our work casts a light for the design of novel,efficient dye-coloring additives,and opens the avenue for the applications of hyperbranched polymers in the field of polymer coloring.