Milli q academic unit

All water was purified to 18MΩ·cm resistivity, with < 10 ppb total organic carbon (Milli-Q Academic Unit, Millipore Corporation, Billerica, MA). The purified water had a surface tension of 71.5 ± 0.4 mN/m measured using a Wilhelmy pin apparatus (Nima Technology Limited, Coventry, England).
Poly(acrylamide) (PA) of molecular mass 5 – 6 MDa (CAS# 9003-05-08) was purchased in powder form from Polysciences (Warrington, PA) and used as received. Aqueous solutions of 1% w/w PA were prepared in the pure water by adding the PA powder in increments of 2 g every 2 – 3 days in a 3/4 full 1 L bottle under nitrogen with continuous gentle mixing on a gyratory shaker (New Brunswick Scientific, Edison, NJ, model G79, speed “4”). After adding the final 2 g of powder, water was added to bring the total volume up to 1 L, and stirring continued for 2 – 3 more days or until the solution was homogeneous, whichever took longer. The observed entanglement concentration is 0.45 wt% [28 (link)]. The surface tension of the PA solution after pouring a fresh sample was 70.8 ± 0.5 mN/m, which typically decreased by ~ 1 – 2 mN/m over 5 minutes. Dilutions to 0.8 wt%, 0.6 wt%, 0.4 wt%, and 0.2 wt% were created from the original 1% stock.

The surfactant sodium dodecylsulfate (>98.5%, Sigma Aldrich, Cat#L3771) (SDS) and the water-soluble dye erythrosine B (>80%, Sigma Aldrich, CAT#E8886) were purchased from Sigma-Aldrich and used as received. SDS purity was verified via the absence of a surface tension minimum at its CMC (Figure S5). All water was deionized and further purified to a resistivity of 18 MΩ·cm using a Milli-Q Academic unit (Millipore Corporation). Polyacrylamide (MW 5MDa-6MDa, Polysciences, Inc. Cat#02806), used to modify subphase viscosity, was solvated into the purified water over the course of several weeks on an orbital shaker in order to ensure complete dissolution. Pyrex glass petri dishes of radius 7 cm were used to hold the subphases for all experiments. All glassware was acid cleaned on the day of use with Nochromix® (Sigma Aldrich, CAT#328693) and sulfuric acid (>95%, Fischer scientific, CAT#A300–212) solution. Between experiments on the same day, the glassware was rinsed with ethanol (>99.5, Pharmco, CAT#111000200), acetone (>99.5%, Pharmco-Aaper, CAT#329000000), and purified water sequentially, and then dried using compressed nitrogen. All experiments were conducted at room temperature, 21±2°C.