Hierarchically Porous MOF-polymer Composites via Interfacial Nanoassembly and Emulsion Polymerizatio

Peng Jin, Wenlong Tan, Jia Huo*, Tingting Liu,Yu Liang, Shuangyin Wang,*andDarren Bradshaw*

S1. Experimental Section

S2. Preparation and characterization of interfacial nanoassembly/ emulsion polymerization

S3. Generality of interfacial nanoassembly/ emulsion polymerization

S4.Knoevenagel condensation reaction catalyzed by ZIF-8-based catalysts

S1. Experimental Section

Materials:All chemicals were purchased from Sinopharm Chemical Reagent Co. Ltd, China and used without pretreatment unless otherwise mentioned. ZIF-8, UiO-66, Cr-MIL-101, and HKUST-1 were synthesized according to previous reports^{1, 2}or with minor modification. Fe₃O₄nanoparticles with an average dimeter of 10 nm were obtained commercially and used without modification.

Synthesis of ZIF-8/PS:Typically,0.70 g ZIF-8 was dispersed in 6 gdeionized(DI)water using ultrasound for30 min. 0.0761 g of2,2'-azobisisoheptonitrile(ABVN)was dissolved in a mixture of 3.3 g divinylbenzene (DVB), 2.2 g styrene,and 0.36 g oleic acid, which was subsequently mixed with the ZIF-8 dispersion in a 20mlsample vial. A stable Pickering emulsion was generated by agitation usingahomogenizerat 14500 rpm for 2.5min. The emulsion was then subsequently polymerized at 65 °C for20 min. Theobtained monolithwas repeatedly washed with ethanol and s dried at120°C under vacuum. For the magnetic ZIF-8/PS,0.07g of Fe₃O₄and 0.63 gZIF-8weresuspended into DI water using ultrasound prior to addition of the monomer solution as for ZIF-8/PS.

Synthesis of UiO-66/PS:Typically,0.50 g UiO-66 was dispersed in4g of DI water by ultrasound for30min.0.0761 g of ABVN was dissolved in a solution of 3.3 g DVB and 2.2 g styrene, and thenthe two solutionsweresubsequently mixed in a 20mlsample vial. A stable Pickering emulsion was generated by agitation using thehomogenizerat 14500 rpm for 2.5min. The resultantemulsion was subsequently polymerized at 65 °C for20 min. Theobtained monolithwas repeatedly washed with ethanol and subsequently dried at120°C under vacuum.

Synthesis of Cr-MIL-101/PS:Typically,0.0817 g of ABVN was dissolved in the solution of4.595g DVB and0.988g 4-vinylpyridine. 0.50 g Cr-MIL-101 was dispersedin 4g DI water by ultrasound for6 h after which time 0.2g NaClwas added into it, and then the two solutions were mixedwith strong stirring (1000 rpm) in a 20mlsample vial. A stable Pickering emulsion was generated by agitation using thehomogenizerat 14500 rpm for 2.5min. The resultantemulsion was subsequently polymerized at 65 °C for20 min. Theobtained monolithwas repeatedly washed with ethanol and subsequently dried at120°C under vacuum.

Synthesis of HKUST-1/PAM:0.30 g HKUST-1 was dispersed in6mLxyleneby ultrasound for6 h. Acrylamide (AM, 1.533 g), N,N′-methylenebisacrylamide (MBAM, 0.311 g), and N-isopropylacrylamide (NIPAM, 0.40 g)were dissolved in4 g of distilled waterto obtainthemonomeraqueous solution. The HKUST-1 dispersion was addedslowlyinto the monomer aqueous solution followed by addition of 0.2 g of 4,4'-azobis(4-cyanovaleric acid) (ACVA)during stirring (1000 rpm). Stirringwas continued for afurther1min after addition.A stable Pickering emulsion was generated with agitationusing thehomogenizerat 14500 rpm for 2.5min. The resultant emulsion was transferred to a preheated oven at 60 °C for20 min. After removal from the oven, theobtained monolithwas continually washed with acetone using a Soxhlet extractor for 24h and then dried under vacuum at120°C overnight.

Characterization:A stable Pickering emulsion was generated using thehomogenizerT10 B S25 (IKA)at 14500 rpm for 2.5min.The phase identification of the samples was performed on a PowderX-raydiffractometer (XRD, D8 Advance) using Cu Kα radiation,wherethe scanning range ofthediffraction angle (2-Theta) is5-50°. The scanning rate was 4° min^-1and step width of 0.02° with 40 mA operation current and 40 kV voltage. Thermogravimetric analysis (TGA) was performed using aHTG-1(HENVEN) instrument and the sample was heated from room temperature to 800^oC at a rate of 10^oC min^-1under an air atmosphere. Scanning electron microscopy (SEM) measurements were made on a Hitachi S-4800 thermal field emission scanning electron microscope at an accelerating voltage of 5, 10, or 15 kV. Samples for SEM measurements were attached to the stub using carbon paste and then sputter-coated with a thin layer of conductive gold to improve electrical conductivity. The nitrogen adsorption-desorption isotherms were measured at 77 K with a JW-BK200C (Beijing JWGB Sci.&Tech. Co., Ltd.) gas adsorption analyser after the sample was first degassed at 120 °C overnight.Specific surface areas were determined by the BET method,mesopore size distribution was obtained based on BJH analysis of the desorption branches of the isotherms,and the total pore volumesweredetermined using the desorption branch of N₂isotherm at p/p⁰= 0.99 (single point).Gas chromatographic (GC) analysis was performed using a Lunan Ruihong SP-7820 instrument equipped with a flame ionization detector (FID) and an SE-54 column (length = 30 m, inner diameter = 0.32 mm, and film thickness = 0.50 μm). The temperature for GC analysis ramped from 60 to 140^oC at 20^oC min^-1and was held at 140^oC for 1 min; then was heated from 140 to 142 at 1^oC/min; and then ramped to 280^oC at 20^oC min^-1and was held them at 280^oC for 2 min. Inlet and detector temperatures were set at 280^oC. n-Dodecane was used as an internal standard to calculate reaction conversion.

Catalyticassessment:The Knoevenagel reaction between malononitrile and benzaldehydeusingthe ZIF-8/PS compositeas thecatalystwas performedinaround bottom flaskwithmagnetic stirring.Typically, amixture of 0.158 g ZIF-8/PS with 0.2 mL(1.96 mmol)benzaldehydeand0.2 mL n-dodecane as an internal standard was placed into a 25mL flask containing 4 mL of toluene. The solution of 0.25 g(3.78 mmol)malononitrile in 1 mL toluene was subsequently added into the flask, andthe resultantmixture was stirred for 12 h at room temperature.The samplewas taken at specific timeintervals and analyzedby GC.After the reaction, the catalyst was removed from the reaction mixture, washed with ethanol for three times,and dried under vacuum at 120 °C for 8 h prior to being reused.

S2. Preparation and characterization of ZIF-8/PS via Interfacial Nanoassembly/ Emulsion Polymerization

Figure S1. Optical microscope image of ZIF-8-stablized emulsionsemployedfor the preparation of ZIF-8/PS composites through polymerization of the continuous phase.The inset shows the size distribution of the emulsion droplets which ultimately form the macropores within the composites.

Figure S2.(a) BJH mesopore size distribution of ZIF-8 nanoparticles and hierarchically porous ZIF-8/PS composites prepared with oleic acid; (b) N₂isotherm (Specific surface area is 118 m²/g) and (c) mesopore size distributionofZIF-8/PS prepared withoutoleic acid demonstrating a reduction in surface area and an absence of mesopores.

Figure S3.Low and high magnificationSEM images of thecross-section ofhierarchically porousZIF-8/PSafter removal of the ZIF-8 particles by acetic acid dissolution, further confirming their localisation within the macropores.

Figure S4.N₂sorptionisotherm(top) andpore-sizedistribution (bottom)ofhierarchically porous ZIF-8/PS after removing the ZIF-8 by acetic acid dissolution.

Figure S5.TGA data of ZIF-8 nanoparticles andhierarchically porousZIF-8/PS composites.

Figure S6. N₂sorption isotherm (top) and pore-size distribution (bottom) ofhierarchically porous ZIF-8/PSprepared without or with different swelling agents.

Table S1.Specific surface area (BET method) of hierarchically porousZIF-8/PSprepared without or with different swelling agents.

1. J. Huo, M. Marcello, A. Garai and D. Bradshaw,Adv. Mater., 2013,25, 2717-2722.

2. L. H. Wee, M. R. Lohe, N. Janssens, S. Kaskel and J. A. Martens,J. Mater. Chem., 2012,22, 13742-13746.