Precursor solutions of pNIPAm were prepared by mixing 1 M NIPAM (Sigma-Aldrich) solution with 0.5 mol % cross-linker (N,N-methylenebisacrylamide; Sigma-Aldrich) and 5 mol % photoinitiator (α-ketoglutaric acid; Sigma-Aldrich) in deionized (DI) water; polyethylene glycol diacrylate (PEG-DA) precursor solutions were prepared by mixing 33% (v/v) PEG(700)-DA (Sigma-Aldrich) with 4% (v/v) photoinitiator (2-hydroxy-2-methylpropiophenone; Sigma-Aldrich) in DI water. Stock solutions of SDS (Sigma-Aldrich), [C6mim][I] (Sigma-Aldrich), and NaOH (EMD Millipore) in DI water, and CaCl2.2H2O (Sigma-Aldrich) and benzoic acid (Acros Organics) in ethanol were prepared and diluted according to the experimental requirements; negative and positive PS suspensions were prepared by suspending 0.25% (v/v) fluorescent sulfonated PS beads, 1 μm in diameter (FS03F; Bangs Laboratories), and 0.5% (v/v) aminated PS beads, 1.8 μm in diameter (PA04N; Bangs Laboratories), respectively, in DI water. Surfactant-free suspensions of decane drops were created by sonicating 2% (v/v) decane (Sigma-Aldrich) in DI water for 1 min.