Hyperbranched Polymeric Fluorosurfactants:Synthesis,Surface Activity and Their Application in Firefighting Foams

Fluorosurfactants are the key ingredients in the formulations of aqueous film-forming foams(AFFFs)for extinguishing flammable liquids,thus developing high-efficient and low-toxic fluorosurfactants is desirable in AFFFs application.Herein,a series of hyperbranched polymeric fluorosu rfactants(HPFs)were successfully synthesized through sequentially modifying hyperbranched polyethylenimine(PEI)with the hydrophilic poly(ethylene glycol)(PEG)chains and the hydrophobic C6/C4-based perfluoroalkyl chains,which were verified by FTIR,^(1)H-and^(19)F-NMR.The surface tensions of all the HPFs in water were measured,and the corresponding physicochemical parameters were interpreted.It was found that the surface activities of HPFs could be tuned through adjusting the ratio of PEG to perfluoroalkyl chains,the length of perfluoroalkyl chains,the molecular weight of PEI core,but not the PEG chain length.In the binary mixture of HPFs with the commercial small molecule fluorosurfactant Capstone^(TM)1157(C1157),a strong synergism led to the elevation of surface activity,which was attributed to the efficient encapsulation of C1157 guests by the compact hyperbranched HPFs as the hosts.The utilization of HPF/C1157 as fluorosurfactant ingredients in AFFF formulations could realize much higher fire-extinguishing efficiency towards flammable oils than the control AFFFs prepa red from the polymeric Capstone^(TM)1460 or the neat C1157.