Physical properties for all solvents studied are listed in Table . The density of TBP is slightly higher than T i BP due to the presence of branched alkyl groups in the latter. The solvent density increases by 15% going from TBP to OP(1PEG)3 (1); the densities then decrease slightly with the addition of increasingly longer PEG arms in (2) and (3). The viscosity of TBP is slightly lower than T i BP and the viscosity of (1) was roughly double that of TBP, with viscosity increasing by a factor of two with each addition of increasingly longer PEG arms. The water content after drying for all molecules was consistently low, despite having been thoroughly water-washed; again, the water content increased slightly with the addition of increasingly longer PEG arms due to the presence of additional hydrophilic ether groups.