Table 2.

Physicochemical surface properties of SS 320, SS 240 and PTFE ^a.

Material	Contact Angle (°) b					Surface Free Energy (mJ m−2) c
	θ TSB	θ MB	θ W	θ D	θ F	${\mathit{\gamma }}_{\mathit{s}}$	${\mathit{y}}_{\mathit{s}}^{\mathit{L}\mathit{W}}$	${\mathit{\gamma }}_{\mathit{s}}^{\mathit{A}\mathit{B}}$	${\mathit{\gamma }}_{\mathit{s}}^{+}$	${\mathit{\gamma }}_{\mathit{s}}^{-}$
SS 320	54.6 ± 1.3	61.4 ± 3.1	65.9 ± 11.7	36.9 ± 5.5	52.7 ± 6.3	41.3 ± 0.4	41.0 ± 0.2	0.3 ± 0.2	0.0 ± 0.0	17.1 ± 0.3
SS 240	58.9 ± 3.2	60.1 ± 4.7	85.6 ± 7.9	41.4 ± 1.1	55.7 ± 8.2	40.7 ± 0.2	39.0 ± 0.1	1.8 ± 0.1	0.5 ± 0.0	1.7 ± 0.1
PTFE	76.3 ± 7.9	94.5 ± 4.5	94.5 ± 8.0	72.8 ± 10.8	66.5 ± 5.8	23.5 ± 0.3	21.2 ± 0.1	2.4 ± 0.1	2.9 ± 0.1	0.5 ± 0.0

^a SS 320 and SS 240, Stainless steel with a grit of 320 and 240; PTFE, polytetrafluoroethylene; θ_TSB, contact angle measured with tryptic soy broth; θ_MB, contact angle measured with milk broth; θ_W, contact angle using water; θ_D, contact angle using diiodomethane; θ_F, contact angle using formamide; ${\gamma }_s$, total surface free energy; $y_s^{LW},$ apolar Lifshitz-van der Waals surface energy component; ${\gamma }_s^{AB}$, Lewis acid–base component; ${\gamma }_s^{+}$, electron-acceptor; ${\gamma }_s^{-}$, electron-donator. ^b Means ± standard errors of a minimum of 4 drops of each liquid on three individual pieces of material as well as ^c means ± standard deviation.