Nanoseeded Catalytic Terpolymerization of CO, Ethylene, and

Aug 23, 2017 - Moreover, the SiO2-190@S-MOP system showed a good activity of 17.2 kg of polymer/g of Pd, comparable to the homogeneous system with 19...
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Nanoseeded Catalytic Terpolymerization of CO, Ethylene, and Propylene by Size-Controlled SiO2@Sulfonated Microporous Organic Polymer Shin Young Kang,†,∇ Yu Na Lim,‡,∇ Yeon-Joo Cheong,‡ Sang Moon Lee,§ Hae Jin Kim,§ Yoon-Joo Ko,∥ Bun Yeoul Lee,⊥ Hye-Young Jang,*,‡ and Seung Uk Son*,† †

Department of Chemistry, Sungkyunkwan University, Suwon 16419, Korea Department of Energy Systems Research, Ajou University, Suwon 16499, Korea § Korea Basic Science Institute, Daejeon 34133, Korea ∥ Laboratory of Nuclear Magnetic Resonance, NCIRF, Seoul National University, Seoul 08826, Korea ⊥ Department of Molecular Science and Technology, Ajou University, Wonchon-dong, Suwon 16499, Korea ‡

S Supporting Information *

ABSTRACT: Nanoseeds with silica@sulfonated microporous organic polymer (SiO2@S-MOP) structure were prepared by the formation of MOP layers on the surface of SiO2 spheres and the successive sulfonation of the MOPs. Using the SiO2@S-MOPs as seed materials, catalytic terpolymerization of CO, ethylene, and propylene was studied. The designed SiO2@S-MOP nanoseeds not only activated catalyst precursors but also controlled the catalytic formation of polyketones. While the homogeneous system showed a severe reactor fouling and a wide molecular weight distribution of terpolymer, the SiO2-190@S-MOP system resulted in the narrow molecular weight distribution of terpolymers without a reactor fouling. The size of nanoseeds was critical to obtaining the granular terpolymers. Moreover, the SiO2-190@S-MOP system showed a good activity of 17.2 kg of polymer/g of Pd, comparable to the homogeneous system with 19.6 kg of polymer/g of Pd. We believe that more various nanoseeded catalytic polymerizations can be developed using new nanoseed materials adopting the MOP chemistry.

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INTRODUCTION Considering the management of C1 gases, polyketones are gaining green credentials because CO can be utilized as a monomer (∼50 wt % CO contents in polymers).1 Simple polyketones are prepared from CO and ethylene to form alternative copolymers.1 However, more efforts have been required to control the physical properties of polyketones.2−7 The insertion of additional alkene monomers is a good way to control the physical properties of polyketones.8−10 For example, the partial insertion of propylene (preferably, 1−4 wt %)11 affects the packing structure of polyketones and lowers their melting temperature (Tm), maintaining a good heat distortion temperature. Thus, terpolymers of CO, ethylene, and propylene are important for practical engineering such as extrusion and injection molding3 and have been commercialized.12 Palladium complexes such as Shell catalysts (see Figure 1) have been used to synthesize polyketones.2−7 Although homogeneous catalysis showed high activity in the production of polyketones, it often suffered from a reactor fouling and a resultant broad distribution of polymer chain lengths. This has © XXXX American Chemical Society

been a serious problem in the continuous synthesis of polyketones. Thus, the polymerization process should be appropriately controlled to produce high quality polyketones. In this regard, seeded polymerization13−17 with heterogeneous seed materials can be an efficient method to control the polymerization process. Moreover, if the catalytic activities of the seeded polymerization are comparable to the homogeneous cases, the synthetic systems can be ideal. To achieve this, efficient seed materials are preferentially required. During the past several decades, various engineering methods for nanomaterials have been developed.18,19 Thus, it is expected that nanoengineered seed systems with a high activity comparable to homogeneous polymerization can be developed. Monodisperse silica nanospheres have been prepared by the Stöber method20 and have been used as versatile platforms for further engineering. Recently, microporous organic polymers Received: Revised: Accepted: Published: A

June 19, 2017 August 21, 2017 August 23, 2017 August 23, 2017 DOI: 10.1021/acs.iecr.7b02509 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

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In this work, we report the engineering of silica@sulfonated microporous organic polymer (SiO2@S-MOP) nanoseeds and their performance in the catalytic terpolymerization of CO, ethylene, and propylene.

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EXPERIMENTAL SECTION Transmission (TEM) and scanning electron microscopy (SEM) images were obtained using a JEOL 2100F and a field emission SEM (JSM6700F), respectively. The elemental mapping by energy dispersive X-ray spectroscopy (EDS) was performed using a JEOL 2100F. The N2 adsorption− desorption isotherm curves were obtained at 77 K using a BELSORP II-mini equipment. The pore size analysis was conducted based on the density functional theory (DFT) method. Powder X-ray diffraction (PXRD) patterns were obtained using a Rigaku MAX-2200. X-ray photoelectron spectroscopy (XPS) was performed using a Thermo VG and monochromatic Al Kα radiation. Infrared absorption spectra (IR) were obtained using a Bruker VERTEX 70 Fourier transform infrared (FT-IR) spectrometer. For the IR spectra of Figure 3a, the inner silica was etched by the treatment of SiO2@S-MOPs with HF solution. Solid phase 13C NMR spectroscopy (CPTOSS) was conducted using a 500 MHz Bruker ADVANCE II NMR spectrometer at the NCIRF of Seoul National University utilizing a 4 mm magic angle spinning probe. The spinning rate was 5 kHz. For the solid 13C NMR spectra in the Supporting Information (SI), the inner silica was etched by treatment of HF solution. The solution phase NMR spectra of polymers were obtained by 500 MHz Varian spectrometers. The solvent was a 1:2 mixture of hexafluoroisopropanol-d2 and benzene-d6. Elemental analysis was conducted using a CE EA1110 instrument. Differential scanning calorimetry (DSC; N650, Sinco Co. Ltd.) curves were recorded under N2 gas at a heating speed of 20 °C/min from

Figure 1. Synthesis of SiO2@S-MOP and the nanoseeded catalytic terpolymerization of CO, ethylene, and propylene.

(MOPs) have been prepared by the coupling of various organic building blocks.21−26 The MOPs can be further functionalized by the postsynthetic modification27−32 including sulfonation33−36 and can be applied as catalytic materials.35,37−40 We expected that the novel nanoseed systems can be developed through the combination of silica nanoplatforms with MOPs.

Table 1. Seeded Catalytic Terpolymerization of CO, Ethylene, and Propylenea entry d

1 2e 3f 4g 5h 6 7 8 9 10 11 12 13 14 15 16 17 18 19

CO (bar)

ethylene (bar)

propylene (bar)b

seed material

30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30

17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 17 21 24

7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 3 0

− − − − − SiO2-750@S-MOPi SiO2-750@S-MOP SiO2-380@S-MOPj SiO2-380@S-MOP SiO2-380@S-MOP SiO2-380@S-MOP SiO2-190@S-MOP SiO2-190@S-MOPk SiO2-190@S-MOP SiO2-190@S-MOP SiO2-190l SiO2-190@MOPl SiO2-190@S-MOP SiO2-190@S-MOP

amt of SO3Hc (μmol)

weight (g)

1.0 2.0 1.0 2.0 3.0 4.0 1.0 2.0 3.0 4.0 0.0 0.0 2.0 2.0

NR 0.58 3.49 3.79 4.17 1.68 1.77 2.40 3.40 1.51 1.38 2.38 3.65 2.40 2.39 NR 0.52 4.30 4.50

activity (kg/g of Pd)

densitym (g/mL)

fouling

2.7 16.4 17.8 19.6 7.9 8.3 11.3 16.0 7.1 6.5 11.2 17.2 11.3 11.2

− − − − 0.22 − 0.22 0.20 − − 0.16 0.30 − −

yes yes yes yes no some no no some some no no some some

2.4 20.2 21.1

0.21 0.31 0.39

no no no

propylene contentn (wt %)

Tm (°C)

Mw

PDIo

4.71

233

551 000

7.36

4.50

232

832 000

8.64

3.84

225

418 000

5.08

5.50

228

161 000

3.52

4.51

232

180 000

3.96

1.69 0.00

244 256

398 000 707 000

5.88 8.95

Reaction conditions: [1,3-bis(di-o-methoxyphenylphosphino)propane]Pd(OAc)2 (1.5 mg, 2 μmol), MeOH (10 mL), 15 h, and 90 °C. bDissolved in solvent. cThe mole number of SO3H in seeds. dNo p-TsOH was used. eAs a promoter, 1.0 μmol of p -TsOH was used. fAs a promoter, 2.0 μmol of p -TsOH was used. gAs a promoter, 3.0 μmol of p -TsOH was used. hAs a promoter, 4.0 μmol of p -TsOH was used. i0.258 mmol of SO3H/g. j 0.336 μmol of SO3H/g. k0.470 μmol of SO3H/g. l4.2 mg was used. mBulk density. nThe values were obtained by 1H NMR spectroscopy. o Polydispersity index. a

B

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Industrial & Engineering Chemistry Research 25 to 300 °C. Gel permeation chromatography (GPC) was performed using a refractive index (RI) detector and a Tosoh EcoSEC HLC-8830. The solvent for GPC analysis was a mixture of hexafluoroisopropanol (HFIP) and 0.01 N trifluoroethanol (TFE). The column, eluting rate, standard polymer, and temperature for GPC measurements were a 2 × TSKgel SuperAWM-H (6.0 × 150 mm), 0.3 mL/min, PMMA, and 40 °C, respectively. Synthetic Procedure for Templates. For the preparation of 190 nm silica spheres,20 ethanol (200 mL), water (23 mL), and ammonium hydroxide solution (28−30%, 7 mL) were added to a 250 mL round bottomed flask. The reaction mixture was stirred for 30 min at 1150 rpm. After tetraethyl orthosilicate (18 mL) was added, the reaction mixture was stirred for 18 h at room temperature. The reaction mixture was poured into a 500 mL Erlenmeyer flask. After dichloromethane (200 mL), hexane (100 mL), and acetic acid (10 drops) were added, the silica particles were collected by centrifugation, washed with a 1:2 mixture of dichloromethane and hexane, and dried in an oven. The bigger silica particles were prepared by repeating the growth process. After the smaller silica particles were added, the growth procedures above were applied. Synthetic Procedure for SiO2@MOP. Pd(PPh3)2Cl2 (17 mg, 0.024 mmol), CuI (4.6 mg, 0.024 mmol), and SiO2-190 (0.55 g) were added to a flame-dried 100 mL Schlenk flask under argon. After triethylamine (60 mL) was added, the reaction mixture was sonicated for 1.5 h. After tetrakis(4ethynylphenyl)methane41 (0.10 g, 0.24 mmol) and 1,4diiodobenzene (0.16 g, 0.48 mmol) were added, the mixture was sonicated for 5 min and then heated at 100 °C for 24 h. After the reaction mixture was cooled to room temperature, the SiO2-190@MOP was collected by centrifugation, washed with dichloromethane, methanol, and acetone, and dried under vacuum. For the preparation of SiO2-380@MOP, SiO2-380 particles (0.85 g) were added instead of SiO2-190. For the preparation of SiO2-750@MOP, SiO2-750 particles (1.10 g) were added instead of SiO2-190. The other procedures were same as those for SiO2-190@MOP. Synthetic Procedure for SiO2@S-MOP. SiO2-190@MOP (0.36 g) and dichloromethane (20 mL) were added to a flamedried 50 mL Schlenk flask. After the temperature of reaction mixture was decreased to 0 °C, ClSO3H (0.90 mL) was added very slowly. After the temperature of reaction mixture was increased slowly to room temperature, the reaction mixture was stirred for 1.5 h under argon. After the temperature of reaction mixture was cooled to 0 °C, excess methanol was added to quench the excess ClSO3H. The powder was washed with a 2:1 mixture of methanol and water until the pH of solvent retrieved after washing became 7.0. Then, the powder was washed with excess methanol and dried under vacuum. The average sizes of silica nanoplatforms were measured by using TEM (10000×) images and by counting 92, 88, and 67 samples for SiO2-190, SiO2-380, and SiO2-750, respectively. Procedure for Catalytic Terpolymerization Reaction. [1,3-Bis(di-o-methoxyphenylphosphino)propane]Pd(OAc)2, i.e., (domppp)-Pd(OAc)2, the Shell catalyst precursor, was prepared by the synthetic procedure in the literature.42 For the reaction of entry 13 in Table 1, (domppp)-Pd(OAc)2 (1.5 mg, 2.0 μmol), SiO2-190@S-MOP (4.2 mg, 2.0 μmol of SO3H, 0.470 mmol of SO3H/g), and methanol (10 mL) were added to an autoclave. After the autoclave was closed, the reaction mixture was stirred for 20 min. Then, propylene gas (5 bar) was charged and the gas was vented. Then, propylene gas (7 bar)

was charged and the reaction mixture was stirred for 5 min. During this process, the charged propylene was dissolved in methanol and the pressure decreased. Ethylene gas (17 bar) was charged. Then, CO (30 bar) was charged. The reaction mixture was stirred (500 rpm) and heated at 90 °C with an oil bath for 15 h. After the autoclave was cooled to room temperature, the excess gases were vented. The product was poured into a 250 mL beaker, washed with methanol, dichloromethane, and diethyl ether, and dried in an oven (65 °C). SiO2-380@S-MOP (5.9 mg, 2.0 μmol of SO3H, 0.336 mmol of SO3H/g) and SiO2-750@S-MOP (7.7 mg, 2.0 μmol of SO3H, 0.258 mmol of SO3H/g) were used for the reactions of entries 9 and 7 in Table 1, respectively. For the reaction of entry 5 in Table 1, p-TsOH (0.76 mg, 4.0 μmol of SO3H) was used instead of SiO2@S-MOP. The bulky densities of polymer in Table 1 were obtained by measuring the volume and weights of polymer powders in glassware.

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RESULTS AND DISCUSSION Figure 1 shows schemes for SiO2@S-MOP nanoseeds and the nanoseeded catalytic terpolymerization. First, we prepared monodisperse silica spheres with average sizes of 748 ± 15, 376 ± 14, and 193 ± 11 nm by the Stöber method,20 denoted as SiO2-750, SiO2-380, and SiO2-190, respectively (Figure 2a−i). Then, MOPs were introduced on the surface of silica spheres by the Sonogashira coupling of tetrakis(4-ethynylphenyl)methane41 and 1,4-diiodobenzene. Through screening reaction conditions, the thicknesses of MOPs on the SiO2 were controlled in the range 20−25 nm. The optimized synthetic conditions are described in the Experimental Section. When the amount of building blocks increased from the optimized ones, MOP materials independent of silica platforms appeared. When the amount of building blocks decreased from the optimized conditions, MOP coating was incomplete. The MOPs of the SiO2@MOP were sulfonated by the treatment with ClSO3H33−36 affording SiO2-750@S-MOP, SiO2-380@S-MOP, and SiO2-190@SMOP. Scanning (SEM) and transmission (TEM) electron microscopies confirmed a uniform coating of MOP layers with 20−25 nm thickness on the SiO2 surface (Figure S1 in the SI). There were no significant changes in the SEM and TEM images of the MOP coating after the sulfonation (Figure 2j−r). The infrared absorption spectroscopy (IR) of the SiO2@MOPs showed main vibration peaks of CC and C−H bonds at 1506 and 820 cm−1, respectively, indicating the formation of MOPs on the SiO2. The IR spectra of SiO2@S-MOP showed new vibration peaks at 3442, 1221, and 1042 cm−1, corresponding to the vibrations of sulfonic acid groups (Figure 3a)43,44 Solid phase 13C nuclear magnetic resonance spectroscopy (NMR) showed significant changes in the aromatic 13C peaks of SiO2@MOP after sulfonation, matching with the observations in the literature33−36 (Figure S2 in the SI). The analysis of N2 adsorption−desorption isotherm curves revealed that the surface areas increased from 5 (SiO2-750), 8 (SiO2-380), and 15 m2/g (SiO2-190) to 87 (SiO2-750@MOP), 119 (SiO2-380@ MOP), and 198 m2/g (SiO2-190@MOP), respectively, through the introduction of MOP on the SiO2. After the postmodification, the surface areas of SiO2-750@S-MOP, SiO2380@S-MOP, and SiO2-190@S-MOP decreased to 41, 49, and 90 m2/g, respectively, matching with the observations in the literature27−36 (Figure 3b). The pore size distribution diagrams C

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Figure 3. (a) IR absorption spectra of SiO2@MOP and SiO2@SMOP. The vibration peaks of sulfonic acids are indicated by asterisks. (b) N2 adsorption−desorption isotherm curves of SiO2, SiO2@MOP and SiO2@S-MOP obtained at 77 K and pore size distribution diagrams of SiO2-190, SiO2-190@MOP, and SiO2-190@S-MOP by a DFT method. Refer to the magnified pore size distribution diagrams in Figure S4 in the SI.

neous distribution of sulfonic acid groups over SiO2@S-MOP nanoseeds (Figure 4a). The surface analysis of SiO2@S-MOPs

Figure 2. SEM images of (a) SiO2-750, (b) SiO2-380, (c) SiO2-190, (j) SiO2-50@S-MOP, (k) SiO2-380@S-MOP, and (l) SiO2-190@S-MOP. TEM images of (d, g) SiO2-750, (e, h) SiO2-380, (f, i) SiO2-190, (m, p) SiO2-750@S-MOP, (n, q) SiO2-380@S-MOP, and (o, r) SiO2190@S-MOP.

Figure 4. (a) EDS−TEM elemental mapping images and (b) XPS spectra of SiO2@S-MOP nanoseeds.

obtained by a DFT method revealed microporosities of SiO2190@MOP and SiO2-190@S-MOP. The powder X-ray diffraction (PXRD) studies showed amorphous characteristic of SiO2@MOP and SiO2@S-MOP, matching well with the properties of conventional MOPs in the literature45−48 (Figure S3 in the SI). According to the elemental analysis via combustion, as the sizes of the inner silica in SiO2@ S-MOP decreased, the contents of sulfonic acid increased from 0.258 mmol/g (0.828 wt % sulfur, SiO2-750@S-MOP), to 0.336 mmol/g (1.077 wt % sulfur, SiO2-380@S-MOP) and 0.470 mmol/g (1.503 wt % sulfur, SiO2-190@S-MOP). The elemental mapping of S and O was conducted by energy dispersive X-ray spectroscopy (EDS), indicating the homoge-

by X-ray photoelectron spectroscopy (XPS) showed the 2p3/2 orbital peak of S and 1s orbital peak of O at 168.8 and 532.1 eV, respectively, matching well with those of S and O in the sulfonic acid group49 (Figure 4b). It has been known that the sulfonic acids can activate [1,3bis(di-o-methoxyphenylphosphino)propane]Pd(OAc)2, the Shell catalyst precursor, via the ligand exchange of the acetate ligand with less coordinating sulfonate to generate acetic acid35,50 (Figure 1). The reaction of the Shell catalyst with methanol generates anionic ligands such as methoxy or hydride which act as initiators for polymerization through migratory D

DOI: 10.1021/acs.iecr.7b02509 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

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Industrial & Engineering Chemistry Research insertion.50 Thus, methanol has been used as solvent in the polymerization for polyketones catalyzed by the Shell catalyst.42,50 The SiO2@S-MOP materials dispersed well in methanol. As the size of SiO2@S-MOP seeds decreased, the dispersion ability in methanol gradually increased. Considering the sulfonic acids and good dispersion ability of SiO2@S-MOP in methanol, we studied the seeded catalytic terpolymerization of CO, ethylene, and propylene in methanol using the Shell catalyst precursor and nanoseeds. The results are summarized in Table 1 and Figure 5.

concentration, catalytic activities decreased, possibly due to the aggregation of seed materials (entries 7, 10, 11, 14, and 15 in Table 1). Under the optimized reaction conditions, the SiO2190@S-MOP system showed catalytic activity up to 17.2 kg of polymer/g of Pd without a reactor fouling (entry 13 in Table 1), comparable to the homogeneous system with activity of 19.6 kg of polymer/g of Pd (entry 5 in Table 1). This promising activity is attributed to the nanosize effect and the promotion role of SiO2@S-MOP. Notably, SiO2-190 and SiO2190@MOP without sulfonic groups resulted in poor performance as seed materials (entries 16 and 17 in Table 1). According to optical microscopy, while homogeneous terpolymerization or seeded one by SiO2-750@S-MOP formed irregular aggregates of polymers with a broad distribution of polymer chains (Figure 5a,b,e and Table 1), the nanoseeded catalytic terpolymerization by SiO2-380@S-MOP and SiO2190@S-MOP formed homogeneous granules of polymers with bulk densities up to 3.0 g/mL and a relatively narrow molecular weight distribution (entries 9 and 13 in Table 1 and Figure 5c,d). We think that the nanoseeds with relatively smaller sizes can be more efficiently dispersed in methanol. The well-dispersed seed systems induce the controlled growth of polymer particles through the efficient activation of Pd catalyst precursors. However, the bigger seeds such as SiO2-750@S-MOPs have relatively poor dispersion ability and can result in facile aggregation in methanol, inducing the poorly controlled growth of polymer powders. Thus, we believe that the sufficiently small sizes of seed materials are critical to obtaining homogeneous granules of terpolymers. The insertion of propylene into the polymers was confirmed by NMR studies (Figure 5g and Figure S6 in the SI). While the polyketone copolymer of CO and ethylene showed the singlet 1 H peak of ethylene moieties at 2.92 ppm, new doublet 1H peaks were observed at 0.92 ppm in the 1H NMR spectra of polyketone terpolymers, corresponding to methyl groups (Figure 5g). The 13C NMR spectrum of polyketone copolymer of CO and ethylene showed two main peaks at 211.6 and 35.1 ppm, corresponding to carbonyl and ethylene moieties, respectively (Figure S6 in the SI). In comparison, additional 13 C peaks of carbonyl and methyl moieties were observed at 215.9 and 15.5 ppm, respectively, and new secondary and tertiary 13C peaks appeared at 44.6, 40.8, and 34.1 ppm, matching well with the expected chemical structure of terpolymers. The IR spectra of polymers confirmed the existence of carbonyl (1693 cm−1) and alkane (2912, 1407, 1334, 1056, and 810 cm−1) groups (Figure S7 in the SI). As the contents of propylene51 increased from 0 wt % to 1.69 and 4.51 wt %, the Tm of polymers gradually decreased from 256 °C to 244 and 232 °C, respectively (entries 13, 18, and 19 in Table 1 and Figure 5f). The terpolymer prepared by homogeneous catalysis with the propylene contents of 4.50 wt % also showed Tm of 232 °C, indicating that the Tm is dependent on the propylene contents (entry 5 in Table 1 and Figure S8 in the SI). It is noteworthy that 1−4 wt % propylene contents in terpolymer of CO, ethylene, and propylene are preferable to maintain a good heat distortion temperature.11 The elemental analysis of polymers showed a gradual increase in C and H from 64.45 and 7.29% (polyketone copolymer in entry 19 in Table 1, calcd values for (C3H4O)n: C, 64.27%; H, 7.19%) to 64.56 and 7.31% (polyketone terpolymer in entry 18 in Table 1, calcd values for [(C3H4O)0.979(C4H6O)0.021]n: C, 64.36%; H, 7.22%), and 64.87

Figure 5. Optical microscopy images (magnification 40×) of terpolymers prepared by using (a) p-TsOH (entry 5 in Table 1), (b) SiO2-750@S-MOP (entry 7 in Table 1), (c) SiO2-380@S-MOP (entry 9 in Table 1), and (d) SiO2-190@S-MOP (entry 13 in Table 1). (e) Photographs, (f) DSC curves, and (g) 1H NMR spectra (a 1:2 mixture of HFIP-d2 and C6D6 of terpolymers and copolymers prepared by SiO2-190@S-MOP.

The heterogeneous systems based on seed materials showed slower polymerization reaction than the homogeneous system (Figure S5 in the SI). The reaction time was optimized to 15 h through investigating the change of total gas pressure of the reaction vessel (Figure S5 in the SI). Homogenous catalyst systems consisting of the Shell catalyst precursor and p-TsOH showed severe reactor fouling (entries 2−5 in Table 1 and Figure 5e). Without p-TsOH, the Shell catalyst precursor was inactive in terpolymerization (entry 1 in Table 1). SiO2@S-MOP showed catalyst activation and antifouling performance for terpolymerization (entries 6, 8, 9, 12, 13, and 18 in Table 1 and Figure 5e). The size effect of SiO2-750@S-MOP and SiO2-350@S-MOP nanoseeds was significant (Figure 5b−d). As the size of nanoseeds decreased, the activity of catalytic systems increased (entries 7, 9, and 13 in Table 1). When the amount of seeds exceeded the appropriate E

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Cationic palladium (II) complexes for CO/vinyl arene copolymerization in the presence of carbon dioxide. Organometallics 2011, 30, 6572−6586. (6) Soomro, S. S.; Cozzula, D.; Leitner, W.; Vogt, H.; Müller, T. E. The microstructure and melt properties of CO−ethylene copolymers with remarkably low CO content. Polym. Chem. 2014, 5, 3831−3837. (7) Takeuchi, D.; Watanabe, K.; Osakada, K. Synthesis of polyketones containing substituted six-membered rings via Pdcatalyzed copolymerization of methylenecyclohexanes with carbon monoxide. Macromolecules 2015, 48, 6745−6749. (8) Mul, W. P.; van der Made, A. W.; Smaardijk, A. A.; Drent, E. Catalytic synthesis of copolymers and terpolymers. In Catalytic Synthesis of Alkene−Carbon Monoxide Copolymers and Cooligomers; Sen, A., Ed.; Kluwer Academic Publishers: Dordrecht, The Netherlands, 2003; pp 87−140. (9) Vavasori, A.; Ronchin, L.; Toniolo, L. Terpolymerization of propene and ethene with carbon monoxide catalyzed by [PdCl2(dppf)] in HCOOH−H2O as a solvent [dppf = 1,1′bis(diphenylphosphino)ferrocene]. Appl. Catal., A 2010, 389, 108− 113. (10) Nakamura, A.; Munakata, K.; Ito, S.; Kochi, T.; Chung, L. W.; Morokuma, K.; Nozaki, K. Pd-catalyzed copolymerization of methyl acrylate with carbon monoxide: structures, properties and mechanistic aspects toward ligand design. J. Am. Chem. Soc. 2011, 133, 6761−6779. (11) Gerlowski, L. E.; Kastelic, J. R.; Korcz, W. H. Method for the fabrication of a multi-ovenable, retortable container apparatus. U.S. Patent 4,996,086, 1991. (12) For example, CARLION based on the terpolymer of CO, ethylene, and propylene was commercialized. (13) Kim, J.-W.; Suh, K.-D. Monodisperse polymer particles synthesized by seeded polymerization techniques. J. Ind. Eng. Chem. 2008, 14, 1−9. (14) Nguyen, D.; Ravaine, S.; Bourgeat-Lami, E.; Duguet, E. About the suitability of the seeded-dispersion polymerization technique for preparing micron-sized silica-polystyrene clusters. J. Mater. Chem. 2010, 20, 9392−9400. (15) Konishi, N.; Fujibayashi, T.; Tanaka, T.; Minami, H.; Okubo, M. Effects of properties of the surface layer of seed particles on the formation of golf ball-like polymer particles by seeded dispersion polymerization. Polym. J. 2010, 42, 66−71. (16) Park, J. H.; Oh, K. H.; Kim, S. H.; Cyriac, A.; Varghese, J. K.; Hwang, M. W.; Lee, B. Y. Morphology control of polymer particles in ethylene/carbon monoxide copolymerization. Angew. Chem., Int. Ed. 2011, 50, 10932−10935. (17) Kang, W. J.; Huh, S. R.; Park, B.-S.; Lee, D.-H.; Yoon, K.-B. Morphology control of ethylene/CO copolymer with a novel inverse suspension polymerization. Catal. Commun. 2015, 62, 100−103. (18) Talapin, D. V.; Lee, J.-S.; Kovalenko, M. V.; Shevchenko, E. V. Prospects of colloidal nanocrystals for electronic and optoelectronic applications. Chem. Rev. 2010, 110, 389−458. (19) Wang, F.; Dong, A.; Buhro, W. E. Solution−Liquid−Solid Synthesis, properties, and applications of one-dimensional colloidal semiconductor nanorods and nanowires. Chem. Rev. 2016, 116, 10888−10933. (20) Stö ber, W.; Fink, A.; Bohn, E. Controlled growth of monodisperse silica spheres in the micron size range. J. Colloid Interface Sci. 1968, 26, 62−69. (21) Bunz, U. H. F.; Seehafer, K.; Geyer, F. L.; Bender, M.; Braun, I.; Smarsly, E.; Freudenberg, J. Porous polymers based on aryleneethynylene building blocks. Macromol. Rapid Commun. 2014, 35, 1466− 1496. (22) Xu, Y.; Jin, S.; Xu, H.; Nagai, A.; Jiang, D. Conjugated microporous polymers: design, synthesis and application. Chem. Soc. Rev. 2013, 42, 8012−8031. (23) Dawson, R.; Cooper, A. I.; Adams, D. J. Nanoporous organic polymer networks. Prog. Polym. Sci. 2012, 37, 530−563. (24) Vilela, F.; Zhang, K.; Antonietti, M. Conjugated porous polymers for energy applications. Energy Environ. Sci. 2012, 5, 7819−7832.

and 7.35% (polyketone terpolymer in entry 13 in Table 1, calcd values for [(C3H4O)0.943(C4H6O)0.057]n: C, 64.51%; H, 7.27%), respectively, through the insertion of propylene.

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CONCLUSION This work shows that the efficient nanoseed materials for catalytic polymerization can be engineered by MOP chemistry.21−26 The size of seeds was critical in the catalytic terpolymerization of CO, ethylene, and propylene. Especially the systems with SiO2-190@S-MOP nanoseed showed catalytic activity up to 17.2 kg of polymer/g of Pd without reactor fouling and the catalytic activity was comparable to a homogeneous catalyst system. Moreover, the polyketone terpolymers obtained by the nanoseeded polymerization revealed a narrower molecular weight distribution compared to those obtained by the homogeneous systems. We believe that more various nanoseeded polymerizations can be developed using new nanoseed materials adopting the MOP chemistry.21−26

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.iecr.7b02509. Synthetic procedure and additional characterization data of seed materials and polyketone terpolymers (PDF)

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AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. *E-mail: [email protected]. ORCID

Bun Yeoul Lee: 0000-0002-1491-6103 Hye-Young Jang: 0000-0003-4471-2328 Seung Uk Son: 0000-0002-4779-9302 Author Contributions ∇

S.Y.K. and Y.N.L.: These authors contributed equally.

Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the C1-gas Refinery Research program (No. 2015M3D3A1A01065436) through the National Research Foundation of Korea funded by the Ministry of Science, ICT & Future Planning.

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DOI: 10.1021/acs.iecr.7b02509 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX