S1

Supplementary Information

Influence of hydrophobization of fumed oxides on interactions with polar and nonpolar adsorbates

V.M. Gun’ko,a,* E.M. Pakhlov,a O.V. Goncharuk,a L.S. Andriyko,a A.I. Marynin,b A.I. Ukrainets,b B. Charmas,c J. Skubiszewska-Zięba,c J.P. Blitzd

a Chuiko Institute of Surface Chemistry, 17 General Naumov Street, 03164 Kyiv, Ukraineb National University of Food Technology, 68 Volodymyrska Street, 01033 Kyiv, Ukraine

c Faculty of Chemistry, Maria Curie-Skłodowska University, 20-031 Lublin, Polandd Eastern Illinois University, Department of Chemistry, Charleston, IL 61920 USA

Nitrogen adsorption-desorption isotherms

Fig. S1. Nitrogen adsorption-desorption isotherms for (a) initial and dimethyl silylated silicas; (b) initial and trimethyl silylated silicas; and (c) initial silica A-300, completely hydrophobized A-200 (AM1) and their mechanical blends as 3 : 1, 1 : 1, and 1 : 3.

S2

IR spectroscopy and textural characteristics

Table S1 Textural characteristics of initial and differently modified silicas calculated using the IR data.Sample SIR,OH

(m2/g)SIR,SiOSi

(m2/g)TMS

(%)SBET

(m2/g)d

(nm)M0 337 312.6 0 234 11.655M0heated at 450 oC

269 0

M1 294 266.6 22.5 235 11.605M2 232 357.5 50.0 231 11.806M3 189 68.7 225 12.121M4 135 251.9 89.4 217 12.568M5 75 1472.7 100.0 216 12.626A-300 270 0 262 10.409A-300heated at 450 oC

290 0

CM1 282 331.9 20.0 244 11.177CM2 264 288.5 35.0 236 11.556CM3 233 207.1 73.0 224 12.175CM4 152 286.2 100.0 212 12.864B1 276 405.3 25.0 238 11.459B2 201 50.0 220 12.397B3 173 235.2 75.0 198 13.774AM1 31 222.6 100.0 178 15.322

Fig. S2. IR spectra of modified nanooxides in the range of the O-H and C-H stretching vibrations.

S3

Fig. S3. Deconvolution of the IR spectra of ST20/HMDS in the range of the O-H and C-H stretching vibrations.

S4

Fig. S4. Deconvolution of the IR spectra of ST76/HMDS in the range of the O-H and C-H stretching vibrations.

S5

Fig. S5. IR spectra of initial (including silica samples preheated at 450 oC for several hours and cooled in air, dashed lines) and modified silicas: (a) first, (b) second, and (c) third series; inserts show the spectra in the range of the O-H stretching vibrations of free silanols.

Thermogravimetry

Thermo-oxidizing destruction of samples (50-300 mg) with recoding thermogravimetric

(TG), differential TG (DTG), and differential thermal analysis (DTA) curves over the 20-1000 oC

range at a heating rate of 10-20 oC/min was studied using a Q-1500D Derivatograph (MOM,

Budapest).

S6

Fig. S6. Thermogravimetry (TG, curve 1) with differential TG (DTG, 2) and thermal analysis (DTA, 3) curves for sample M5.

Fig. S7. Thermogravimetry (TG, curve 1) with differential TG (DTG, 2) and thermal analysis (DTA, 3) curves for sample CM4.

S7

Fig. S8. Thermogravimetry (TG, curves 1 and 4) with differential TG (DTG, 2 and 5) and thermal analysis (DTA, 3 and 6) curves for ST20 and ST76 modified by HMDS.

Fig. S9. Thermogravimetry (TG, curves 1 and 4) with differential TG (DTG, 2 and 5) and thermal analysis (DTA, 3 and 6) curves for ST20 and ST76 modified by PDMS/DMC.

The TG data was used to compute the pore size distribution (PSD) using a thermoporometry

method described in detail elsewhere [11].

S8

Fig. S10. Thermoporometry (TG) results for the PSD based on TG data for desorbed water up to 200 oC (curves 1), DSC thermoporometry with adsorbed water (curves 2) and SCV/SCR PSD based on nitrogen adsorption-desorption data (curves 3) for (a) ST20/HDMS and (b) ST76/HDMS (thermoporometry curves were renormalized for better view).

S9

Evaporation of ethanol

Fig. S11. Evaporation of ethanol (0.5 g per 0.05 g of oxide) as a relative amount mev/m0 (where mev and m0 are the evaporated and initial ethanol masses, respectively) from suspensions containing silicas of series: (a, b) M0-M5; (c, d) CM1-CM4 and A-300; and (e, f) B1-B3, A-300, and AM1; (a, c, d) total curves and (b, d, f) final part (over the 1350-1900 min range) of curves.

Theoretical calculations

Table S2 shows results of quantum chemical calculations of silica clusters with different

degree of hydrophobization (in the gas and liquid phases) using the DFT (Gaussian 09) [1] and

field view (TorchLite 10.3) [2,3] methods. For visualization, UCSF Chimera 1.12 [4] and

ChemCraft 4.89 [5] packages were used.

S10

Table S2. Quantum chemical estimation of the hydrophobization effects on solvation with ethanol and water (SMD method).Model Et (Ha) Medium Esol (kJ/mol) Basis set (geometry) Basis set (energy)Si8O12(OH)8 -3815.09974140 vacuum - cc-pVDZ cc-pVDZ

-3826.27502814 vacuum - 6-31G(d,p) B97X-D/cc-pVDZ-3826.29513474 vacuum - cc-pVDZ B97X-D/cc-pVDZ-3826.34801296 ethanol -138.8 cc-pVDZ B97X-D/cc-pVDZ-3826.35289829 water -151.7 cc-pVDZ B97X-D/cc-pVDZ-3826.30360533 vacuum - B97X-D/cc-pVDZ B97X-D/cc-pVDZ-3826.32671494 ethanol -135.7 6-31G(d,p) B97X-D/cc-pVDZ-3826.33089333 water -146.7 6-31G(d,p) B97X-D/cc-pVDZ-3826.35822661 ethanol -143.4 B97X-D/cc-pVDZ B97X-D/cc-pVDZ-3826.36450303 water -159.9 B97X-D/cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)7OSi(CH3)3 -4234.97733697 vacuum cc-pVDZ B97X-D/cc-pVDZ-4235.02655621 ethanol -129.2 cc-pVDZ B97X-D/cc-pVDZ-4235.02607484 water -128.0 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)6(OSi(CH3)3)2 -4643.65976190 vacuum cc-pVDZ B97X-D/cc-pVDZ-4643.70519902 ethanol -119.3 cc-pVDZ B97X-D/cc-pVDZ-4643.69933412 water -103.9 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)5(OSi(CH3)3)3 -5052.34166422 vacuum cc-pVDZ B97X-D/cc-pVDZ-5052.38348082 ethanol -109.8 cc-pVDZ B97X-D/cc-pVDZ-5052.37217526 water -80.1 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)4(OSi(CH3)3)4 -5461.02409611 vacuum cc-pVDZ B97X-D/cc-pVDZ-5461.06232806 ethanol -100.4 cc-pVDZ B97X-D/cc-pVDZ-5461.04557965 water -56.4 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)3(OSi(CH3)3)5 -5869.70693241 vacuum cc-pVDZ B97X-D/cc-pVDZ-5869.74154533 ethanol -90.9 cc-pVDZ B97X-D/cc-pVDZ-5869.71952406 water -33.1 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)2(OSi(CH3)3)6 -6278.38928567 vacuum cc-pVDZ B97X-D/cc-pVDZ-6278.42051492 ethanol -82.0 cc-pVDZ B97X-D/cc-pVDZ-6278.39304530 water -9.9 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OH)(OSi(CH3)3)7 -6687.07247037 vacuum cc-pVDZ B97X-D/cc-pVDZ-6687.10004963 ethanol -72.4 cc-pVDZ B97X-D/cc-pVDZ-6687.06722340 water 13.8 cc-pVDZ B97X-D/cc-pVDZ

Si8O12(OSi(CH3)3)8 -7095.75706243 vacuum cc-pVDZ B97X-D/cc-pVDZ-7095.78121654 ethanol -63.4 cc-pVDZ B97X-D/cc-pVDZ-7095.74296444 water 37.0 cc-pVDZ B97X-D/cc-pVDZ

Note. Et and Esol are the total (with consideration of solvation using SMD method) and solvation energies, respectively.

S11

(a)

(b)

(c)

Fig. S12. Clusters of silica initial and modified by the TMS groups: structure (right column) and fields (left column) (TorchLite 10.4.2) [2,3], where

S12

Fig. S13. 1H NMR spectra of water (curve 1) bound to silylated nanosilica A380/HMDS at MS = 30% [12], and theoretical calculations using PM7 method [13] with a correlation function [9] for water (2) bound to partially silylated (by TMS) silica nanoparticles and (3) free droplet with 2000 H2O.

S13

DSC

Gibbs-Thomson relation for the freezing point depression can be written upon the use of melting DSC thermograms of bound water (ice) [6-9] as follows:

Rp (nm)=0.68−k DSC /(T m−T m 0) , (S1)where kDSC = 32.33 K nm (water) or 64 K nm (decane), Tm and Tm0 are the melting temperatures of confined and bulk water or decane, respectively. The pore size distribution dV/dR can be calculated from the DSC melting thermograms of bound ice [6-9]

dVdR

(cm3nm−1 g−1 )=

dqdt

(T m−T m 0)2

k DSC ρβ mΔH (T ) , (S2)where dq/dt, , , m and H(T) are the DSC heat flow, the water density, the heating rate, the sample mass and the melting enthalpy of ice, respectively. The H values as a function of temperature for water can be estimated as follows [6-9]

ΔH (T )(J g−1 )=332+11.39 (T m−T m0 )+0 . 155(Tm−Tm0 )2. (S3)

Enthalpy of fusion at freezing point is 333.5 (water) and 201.82 (n-decane) J/g [10]. Values of H < 0 and H > 0 correspond to exotherms and endotherms, respectively.

Table S3. Masses of samples studied upon water interacting with fumed oxides at a cooling-heating rate of 10 oC/min, and enthalpy of maximal exotherm (cooling) and endotherm (heating) of DCS curves.Sample Adsorbent

mass (mg)Adsorbate mass (mg)

Vads

(cm3/g)Hmax (J/g)

(cooling) (T oC)Hmax (J/g)

(heating) (T oC)M0 1.298 1.750 1.348 59.0 (-23.07) 147.3 (-3.70)M1 1.127 3.230 2.866 144.3 (-16.30) 156.5 (-2.53)M2 1.091 2.320 2.126 152.2 (-15.99) 143.9 (-2.87)M3 1.094 0.680 0.622 95.8 (-23.57) 98.7 (-0.001)M4 1.047 0.980 0.936 255.9 (-25.06) 296.5 (1.33)M5 1.314 0.290 0.221 24.5 (-25.42) 30.6 (-1.17)A-300 1.605 4.765 2.969 136.9 (19.95) 167.5 (-2.54)CM1 1.019 4.230 4.151 104.2 (-21.81) 89.4 (-3.21)CM2 1.294 3.070 2.372 100.1 (-12.66) 177.3 (-2.70)CM3 1.215 1.050 0.864 94.2 (-2.66) 17.8 (-2.35)CM4 0.999 0.580 0.581 25.0 (-22.76) 20.9 (-1.52)A-300 1.607 6.00 3.734 163.2 (-14.73) 159.0 (-4.05)B1 1.179 2.930 2.485 132.7 (-10.98) 34.9 (-2.69)B2 1.232 1.670 1.356 127.4 (-15.04) 155.1 (-0.67)B3 1.272 1.110 0.873 117.6 (-16.05) 101.3 (-0.002)AM1 1.174 1.070 0.911 131.1 (-11.52) 122.6 (-0.002)ST20+HMDS 1.907 0.320 0.168 105.1 (-22.59) 111.7 (-1.01)ST20+PDMS/DMC 1.843 0.814 0.442 27.7 (2.84) 155.0 (-2.67)ST76 2.342 2.980 1.272 174.6 (-19.74) 200.8 (-3.19)ST76+HMDS 2.533 0.630 0.249 56.5 (-23.2) 55.2 (-2.83)ST76+PDMS/DMC 3.827 0.615 0.161 51.5 (-18.71) 87.3 (-2.83)AST71 1.739 2.570 1.478 249.6 (-13.23) 210.1 (-4.35)

S14

Table S4. Masses of samples studied upon n-decane interacting with fumed oxides at a cooling-heating rate of 10 oC/min, and enthalpy of maximal exotherm (cooling) and endotherm (heating) of DSC curves.Sample Adsorbent

mass (mg)Adsorbate mass (mg)

Vads

(cm3/g)Hmax (J/g)

(cooling) (T oC)Hmax (J/g)

(heating) (T oC)M0 1.589 2.285 1.970 146.3 (-42.51) 154.2 (-35.25)M1 1.283 2.212 2.362 147.0 (-41.16) 156.2 (-35.25)M2 1.041 2.168 2.853 146.4 (-41.48) 156.7 (-35.25)M3 1.354 2.806 2.839 160.5 (-42.96) 151.4 (-35.09)M4 1.290 2.923 3.104 146.7 (-40.30) 155.1 (-34.92)M5 1.246 2.714 2.984 126.7 (-41.92) 145.3 (-35.08)A-300 1.297 3.083 3.256 153.0 (-41.00) 162.6 (-35.11)CM1 1.443 2.968 2.818 148.3 (-41.15) 156.7 (-35.11)CM2 1.220 3.127 3.511 154.1 (-42.25) 157.5 (-34.92)CM3 1.333 2.210 2.271 141.2 (-42.81) 151.7 (-35.90)CM4 1.453 2.659 2.507 145.6 (-42.80) 155.3 (-35.93)B1 1.146 2.963 3.542 150.2 (-41.29) 157.9 (-35.09)B2 1.357 2.284 2.306 149.1 (-43.44) 153.9 (-35.75)B3 1.738 2.940 2.317 160.5 (-44.39) 159.0 (-35.59)AM1 1.648 2.510 2.086 135.8 (-44.38) 144.4 (-35.66)ST20+HMDS 2.308 2.366 1.404 146.8 (-42.28) 149.2 (-35.08)ST20+PDMS/DMC 2.189 1.660 1.039 156.2 (-42.44) 150.1 (-35.08)ST-76 2.177 2.230 1.403 150.3 (-41.76) 153.6 (-34.74)ST76+HMDS 3.677 2.153 0.802 157.1 (-43.89) 159.0 (-34.91)ST76+PDMS/DMC 3.777 1.635 0.593 166.0 (-42.45) 162.5 (-34.58)AST71 1.826 2.215 1.662 164.8 (-41.93) 159.1 (-34.42)

S15

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