Aerosil 150

Fumed silica suspensions (8% w/w) were used as the shear thickening fluid28 . Fumed silica powder (Aerosil 150, Evonik, Germany) was mixed thoroughly with poly(propylene glycol) (PPG, M_w=725, Sigma-Aldrich). The solution was then degassed for 3 h.
Hyaluronic acid (6 mg ml⁻¹) was used as the shear thinning fluid. Hyaluronic acid powder (53747, Sigma-aldrich) was mixed in PBS (Gibco, Life Technologies) and stirred under room temperature for 48 h.
Glycerol (99.5%, 1,410 mPa s at 20 °C, VWR, France) and silicone oil (Dow Corning 200/12,500 cSt, VWR, UK) were used as Newtonian fluids for the micro-scallop and macro-scallop, respectively.
The viscosities were measured using shear rate ramp experiments on a rheometer (Kinexus Pro, Malven, UK) using a plate-to-plate (40 mm in diameter) set-up. The temperature was set to 25 °C. The viscosity was measured in the range of 0.05–300 s⁻¹ with a 4-min ramp time. The data shown in Fig. 5 and Supplementary Fig. 9 are the average of three independent measurements of two fluids, respectively.

A bisphenol A-type epoxy resin (YD-115, E.E.W. 187 g/eq, KUKDO CHEMICAL CO., Seoul, Republic of Korea) containing diglycidyl ether of bisphenol A (DGEBA) with butyl glycidyl ether (BGE) was used. Butyl glycidyl ether (BGE) and polyether diamines (JEFFAMINE^® D-230, A.H.E.W. 60 g/eq, HUNTSMAN Corporation, Salt Lake City, TX, USA ) were used as the curing agents. The molecular structures of the epoxy and polyether diamines are shown in Figure 1a.
Fumed silica (AEROSIL^®150; surface area: 150 ± 15 m²/g) and PDMS-treated fumed silica (AEROSIL^®R202; surface area: 100 ± 20 m²/g) were provided by Evonik Industries (Essen, Germany).