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Experimental Procedures PSZ MEL nanoparticle suspensions were synthesized by adding 19.97 g of tetrabutylammonium hydroxide (TBAOH, 55%, Sachem) to 30 g of tetraethylorthosilicate (TEOS, 98%, Sigma-Aldrich) in a polypropylene bottle with stirring. 21.49 g of double-deionized water (DDI H2O) was then added for a final molar ratio of 0.3 TBAOH : 1 SiO2 : 4 C2H5OH : 10 H2O, and the solution was aged at room temperature with stirring for 24 h. The bottle was then placed into a convection oven with stirring at 80 °C for 48 h. The solution was subsequently transferred to Teflon®lined autoclaves and placed into a convection oven at 114 °C for 24 h with no stirring. The resulting nanoparticle suspension had particle sizes of about 80 nm. Equal parts of 1-butanol (anhydrous, 99.8%, Sigma-Aldrich) and zeolite nanoparticle suspension were mixed, and then 0-12% TEOS was added. (For example, 47% nanoparticle suspension, 47% 1-butanol, and 6% TEOS; all ratios are by mass.) This solution was aged with stirring at room temperature for 16 h, and PSZ MEL thin films were prepared by spin coating the mixture onto silicon wafers at 3000 rpm for 30 s with an acceleration of 1275 rpm/s. The zeolite nanoparticle suspension synthesis and film preparation procedures are similar to those previously published, except that TEOS is added to the nanoparticle suspension before the spin-on process.1 The films with 0-12% TEOS were immediately placed into a tubular furnace with a nitrogen environment. The temperature was increased from room temperature to 113 °C at 1 °C/min and held at 113 °C for 24 h. Then, the temperature was raised to 400 °C with a ramp rate of 1 °C/min. Nitrogen was used as the carrier gas and flowed through a bubbler containing 1:1 (by mass) toluene (99.8%, EMD Chemicals, Inc.):hexamethyldisilazane (HMDS, 98%, Alfa Aesar) with a flow rate of approximately 3 L/h during the temperature ramping to 400 °C. The temperature was held at 400 °C for 2 h, after which the vapor flow was stopped, and the furnace was allowed to cool to room temperature in the static HMDS environment. Particle size of the nanoparticle suspension was measured on a Brookhaven Instruments Corporation ZetaPALS and confirmed through transmission electron microscopy. Zeolite films were imaged by transmission electron microscopy (TEM) using a Philips CM300 microscope at 200 kV, while the morphological features were investigated using a FEI Technai TEM (T-20, 200kV). TEM specimens were prepared by scraping film material with a razor blade and dispersing it in ethanol. The solution (~50 μL) was pipetted onto carbon copper/Formvar grids (Electron Microscopy Sciences), which were dried at room temperature for 1 hour. Film thickness was measured on a Jobin Yvon UVISEL spectroscopic phase-modulated ellipsometer. The porosity and pore size distribution were calculated from toluene adsorption isotherms measured on a fixed angle ellipsometric porosimeter with wavelengths of 300-800 nm. The reduced elastic modulus (Er) and hardness (H) were measured with a Hysitron, Inc. Ubil nanomechanical test instrument. A cube corner diamond indenter tip with a total included angle of 90 º and a nominal tip radius of 40 nm was used, and the applied forces ranged from 5 to 100 µN. Er and H were determined from the load-displacement information by the procedures developed by Oliver and Pharr.2 References (1) Li, Z. J.; Lew, C. M.; Li, S.; Medina, D. I.; Yan, Y. S. J. Phys. Chem. B 2005, 109, 8652-8658. (2) Oliver, W. C.; Pharr, G. M. J. Mater. Res. 1992, 7, 1564-1583.