Supplementary Section
Supplementary Section-1: Surface Fabrication and Characterization
Surface fabrication: Flat silicon substrates were coated with self-assembled monolayers
of 2-[methoxy(polyethyleneoxy) propyl] trimethoxysilane (Mw = 660 g/mol), 3,3,3trifluoropropyl trimethoxysilane and trideca fluoro- 1,1,2- tetrahydroxyl trichlorosilane
(Mw = 482 g/mol) from Gelest. These samples are called as Si-PEG, Si-Trifluoro and and
Si-F respectively. Self-assembled monolayers were deposited on plasma treated silicon
substrates from either the vapor phase or solution. Nano-structured silicon surfaces
composed of single (Si-STex-F) and double (Si-DTex-F) arrays of posts were fabricated
using standard photolithography and reactive ion etching processes. Lateral dimensions,
spacing and heights of the posts on the nanostructured silicon surfaces were as follows:

Si-STex-F: 0.75x0.5x1.7 µm (the solid fraction φ of this surface is 0.36)

Si-DTex-F: large features: 15x7x8 µm; small features: 0.75x0.5x2 µm
Subsequently, self-assembled monolayers of trideca fluoro- 1,1,2-tetrahydroxyl
trichlorosilane (from Gelest) were deposited on the textured surfaces. An as received Si
wafer, which was cleaned with acetone, methanol and isopropanol, was also used in the
experiments.
Contact Angle: Static and roll-off contact angles of sessile deionized water (DI) water
droplets were measured on all the samples at room temperature using a VCA Optima set
up from AST Products, Inc. The error in the contact angle measurements is 1 degree.
Supplementary Section-2: Maximum and Steady-State Spread Diameter as
Function of Contact Angle
Spread diameter (mm)
10
Maximum spread
Final spread
8
6
4
2
0
0
20
40
60
80
100
120
140
160
Contact angle (deg)
FIG S1. Variation of maximum and final state spread diameters as a function of static contact angle. All
experiments were performed at room temperature. Lines are only intended to serve as a guide. Although,
both parameters are a function of surface wetting properties, the final state diameter shows a much stronger
dependence on surface wetting properties.
Supplementary Section-3: Temperature Dependence of Wetting Dynamics during
Droplet Impact
Additional experiments were carried out to ensure that phase transition did not influence
droplet impact dynamics. A series of control experiments were performed, where salt
water droplets (75% DI water + 25% CaCl2 (calcium chloride)) were impinged on these
surfaces instead of pure DI water. Addition of salt reduces the freezing point of water to –
30 °C, eliminating the probability of freezing during impact. As shown in Figure S2 of
the supplementary section, pure and salt water droplets show remarkably similar wetting
dynamics for all substrates, discarding the icing phase transition as plausible explanation
of the experimental results. In addition, we have conducted (infrared) IR thermometry
experiments to determine the freezing kinetics of single water droplets on these
substrates. Our results suggest that the earliest onset of freezing, which happens on the
hydrophilic PEG sample, occurs 1-2 seconds subsequent to droplet impact.
The
remarkable slowing down of PEG wetting dynamics as shown in Figure S2b) occurs at
much earlier stage (10 ms after impact).
Si-PEG, DI water
Spread diameter/ mm
-15°C
22°C
85°C
Si-PEG, DI water
8
6
4
2
0
0
10
Spread diameter / mm
10
(a)
8
Si-Double
Texture5
10 F- DI water
15
-15°C
22°C
85°C
6
4
2
0
0
10
Time (ms)
(c)
Si-Double Textured-F, DI water
(b)
8 Si-PEG, DI water+ 20% CaCl 2
20
Spread diameter / mm
Spread diameter/ mm
10
-15°C
22°C
85°C
6
4
2
5
10
15
Time (ms)
(d)
-15°C
22°C
85°C
Si- Double Textured-F,
DI water+ 20% CaCl 2
8
20
6
4
2
0
0
0
5
10
Time (ms)
15
20
0
5
10
Time (ms)
15
20
FIG S2. Variation of spread diameter as a function of time and temperature. Si-PEG:( a) DI Water,( b) DI
water + 25% CaCl2. Si-Double Textured-F: (c) DI Water, (d) DI water + 25% CaCl2. Water droplet
diameter and velocity were equal to 2 mm and 2.3 m/s, respectively. These figures reveal the profound
impact of surface temperature on water droplet impact dynamics on hydrophilic surfaces (in the absence of
freezing). It should also be noted that the effect of temperature on impact dynamics on superhydrophobic
surfaces is negligible due to a limited heat transfer path.