Immobilization of Mesoporous Silica Particles on Stainless Steel Plates

Supplementary Informations

Immobilization of Mesoporous Silica Particles on Stainless Steel Plates.

LUIGI PASQUA

Department of Environmental and Chemical Engineering, University of Calabria, Via P. Bucci 45 a, 87036 Rende (CS) Italy

MARCO MORRA

NobilBio Ricerche s.r.l., Str. S. Rocco 36, 14018 Villafranca d'Asti, Italy

Experimentals

Reagents.

Pluronic P-123, tetraethylorthosilicate, and aminopropyltriethoxysilane were purchased from Sigma and used without further purification. The stainless steel dishes were obtained by NobilBio.

Surface functionalization of stainless steel (SS) substrates

Surface functionalization of stainless steel (SS) substrates was obtained by the introduction of amino groups via deposition from allylamine plasma. Briefly, allylaminevapor was introduced from a reservoir kept at room temperature (R.T.) into a stainless steel, capacitively coupled parallel-plate reactor. The reactor is equipped with a RF generator (13.56 MHz) and internal electrodes. The distance between the electrodes was 10 cm. The monomer flow rate, as evaluated by the increase of the pressure with the pump turned off, is about 50 sccm (standard cubic centimeter per minute). The pressure, before switching on the discharge, was 200 mTorr. The samples were located on the water-cooled grounded electrode and deposition, using a discharge power of 100 W, was performed for 30 s, using a pulsed plasma with a duty cycle of 4 ms on and 4 ms off. After treatment and prolonged rinsing in doubly distilled water, samples were dried under a laminar flow hood.

Preparation of mesoporous silica (MS).

SBA-15 mesoporous material was synthesized at 35°C using Pluronic P123 surfactant. In a typical preparation 4.0 g of Pluronic P123 was dissolved in 30 g of water and 120 g of 2M HCl solution with stirring at 35°C. Then 8.50 g of tetraethylorthosilicate (TEOS) was added with stirring at 35°C for 20 hours. The mixture was aged at 80°C overnight without stirring. The solid product was recovered, washed and air dried at RT. The obtained material was calcined in air at 550° C for 8 hours.

Preparation of 3-aminopropyl-mesoporous silica (APMS).

The APMS material was prepared by post-synthetic grafting of aminopropyltriethoxysilane (APTES) on the silica surface of calcined MS (MSC).

MSC (1g ) was suspended in 12 ml of anidrous toluene then 2,5 ml of APTES were added. The mixture was stirred under reflux for 6 hours, then filtered and washed with diethyl ether.

Functionalization of amino-derivatized stainless steel dishes with a COOH-terminal spacer (Plate A).

An amino-derivatized stainless steel dish (AD) was immersed in dichloromethane (12 ml), then triethylamine (1,5 ml) and finally glutaryl dichloride (1,8 ml) were added and the suspension was stirred for 48 hours. The functionalized dish (ADG-COOH) was then removed and washed with dioxane.

Functionalization of amino-derivatized stainless steel dishes with a COOH-terminal spacer (Plate B).

An amino-derivatized stainless steel plate (AD) was immersed in tetrahydrofuran (8 ml) and then 2-bromo–2 metil propionic acid (312 mg) was added.

The mixture was stirred for 6 days; the functionalized dish (AD-COOH) is removed and washed with dioxane.

Anchoring of APMS particles to the ADG-COOH. (Plate A)

The functionalized dish (ADG-COOH) was suspended in dioxane (10ml); then APMS (100 mg), previously activated in oven at 100 °C, was added and the suspension stirred for 48 hours; the suspension was then removed and the dish (ADG-COO-+H3N-(CH2)3-MS) washed with dioxane.

Anchoring of APMS particles to the AD-COOH (Plate B).

AD-COOH dish was suspended in dioxane (4 ml); diisopropylcarbodiimide (0.5 ml) was then added. The suspension was stirred for 45 minutes, APMS particles (100 mg), previously activated in oven at 100 °C, was then added and the suspension stirred for 48 hours then, the obtained plate AD-CON(H)-(CH2)3-MS) washed with dioxane.

Characterization

XPS analysishasbeencarried out using a Perkin Elmer PHI 5400 ESCA System with an X raysourcewith Mg anode. The pressure in theanalysischamber was keptaround 10-9 Torr andthe power at 200 W. The analysisresultsareexpressed in atomicpercent.

X-Ray powder diffraction patterns were measured on a RigakuMiniflex 600 diffractometer using Cu-K radiation (40 Kv, 15 mA) over the range 0.5°<2<10°.

The N2 adsorption-desorption volumetric isotherms at 77 K were measured on a Micromeritics Asap 2010 apparatus. Samples were pre-treated under vacuum at 110°C to a residual pressure of 2·10-3 mm Hg. Surface area of the samples was calculated by BET linearization in the pressure range 0.05 to 0.2 P/P0. Lattice pore volume was obtained from the amount of nitrogen gas adsorbed at the top of the rising section of the isotherm. SEM micrograph was collected using a FEI Quanta 200 instrument and a Jeol JXA 8230 EMPA.

TEM micrographs were acquired using a JEOL GEM 1400 Plus working at 80 Kv.

FT-IR spectra were acquired on a Jasco FT/IR 4600.

Figure S1. FT-IR spectra of Plate A, Plate B and starting APMS material