Versatile Adamantane-based porous polymers with enhanced microporosity for efficient CO2 capture and iodine removal

Accepted Manuscript Versatile Adamantane-based Porous Polymers with Enhanced Microporosity for Efficient CO2 Capture and Iodine Removal† Dongyang Chen, Yu Fu, Wenguang Yu, Guipeng Yu, Chunyue Pan PII: DOI: Reference:

S1385-8947(17)31844-2 https://doi.org/10.1016/j.cej.2017.10.133 CEJ 17917

To appear in:

Chemical Engineering Journal

Received Date: Revised Date: Accepted Date:

20 August 2017 18 October 2017 20 October 2017

Please cite this article as: D. Chen, Y. Fu, W. Yu, G. Yu, C. Pan, Versatile Adamantane-based Porous Polymers with Enhanced Microporosity for Efficient CO2 Capture and Iodine Removal†, Chemical Engineering Journal (2017), doi: https://doi.org/10.1016/j.cej.2017.10.133

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Versatile Adamantane-based Porous Polymers with Enhanced Microporosity for Efficient CO2 Capture and Iodine Removal† Dongyang Chena, Yu Fua, Wenguang Yua, Guipeng Yu*a,b, Chunyue Pan a,b a

College of Chemistry and Chemical Engineering, Central South University, Changsha, 410083, China

b

Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources, Central South University, Changsha 410083, China.

*

Corresponding author. E-mail address: [email protected] (Guipeng Yu)

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Abstract: A series of multifunctional nanoporous organic polymers with high microporosity have been successfully synthesized via Friedel-Crafts alkylation and Scholl coupling reactions. Porous properties are well-controllable by simply regulating the lengths and rigidities of linkers, where the rigid tetrahedral building block, i.e. 1,3,5,7-tetraphenyladamantane, knitted with flexible alkyl chains leads to a hierarchically porous structure of NOP-53. Such amorphous materials derived from the high rigid building block achieve high surface areas (1178 m2 g-1 for NOP-54) and substantially improved micro-pore volumes (0.86 cm3 g-1, Vmicro/Vtotal=65 %). The asmade porous network NOP-54 featuring highest microporosity can uptake 14.2 wt% CO2 at 273 K and 1 bar, and good selectivity ratios for CO2 adsorption over N2 (56.1) and CH4 (13.9) at 273 K are achieved. Furthermore, such polymers display excellent iodine vapor uptake of up to 202 wt% and shows remarkable capability as iodine sorbent in solution. These results are significant for constructing accessible aromatic networks with promoted microporosity targeting for environmental challenges. Keywords: Nanoporous organic polymer; CO2 capture; iodine adsorption; promoted microprosity; 1,3,5,7-tetraphenyladamantane; hierarchically porous structure

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

1. Introduction A dominant challenge in current environmental remediation is the exploration of costeffecitve adsorbents bearing high affinity towards guest molecules, to achieve both rapid uptake and high capacity for the contaminants. As an important member of sorbents, nanoporous organic polymers (NOPs)[1-2] have gained significant attention due to their highly tunable molecular design, high surface areas, low skeleton densities, good physicochemical stabilities and tunable porosities. They have been extensively explored in a wide range of applications pertinent to energy and environmental sustainability, such as adsorption[3], catalysis[4], separation[5], and electrochemical sensors[6], etc. However, the pursuing of the versatile NOPs for two or more taskspecific functionality is still a contemporary field of materials chemistry. To achieve efficient adsorption, especially for the capture of small molecules such as carbon dioxide, methane and radiated iodine et al., suitable interactions of guest molecules with the NOPs are highly desired, which can lead to high selective adsorption capacity and energy-effective regeneration. The incorporation of heteroatom or open metal sites into the NOPs skeletons, has been demostrated to be effective strategy to improve CO2 adsorption and its selectivtity over N2 and CH4 gases[3]. Besides, pore parameters including surface area, pore volume, and pore size distribution are crucial to obatin efficient sorbents as well. It has been reported that microporosity, especially ultramicroporous pores (<1.0 nm) can effectively provide strong interaction with CO2 molecules, consequently, leading to high CO2/N2 selectivity and CO2 capture[7-10]. However, purely microporous networks have some limitations, such as low permeability, inefficient diffusion and restricted access to active sites, etc[11-15]. In other words, the ability of adsorbate transfer/diffusion within the pore texture and high

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

molecule accessible surface area also play an indispenable roles in achieving high performance CO2 caputure. Park[16], Inagaki[17], and our group[18] found that polymer materials with continuous hierarchical porosity achieved improved

pore

volume (4 cm3 g-1) and gas adsorption capacities (CO2: 23.7 wt%, 273 K/1bar) by integrating the advantages of multiple length scale porosity. The mesopores provide effective transport pathways, and the micropores provide the dominat adsorption sites for guest species. Therefore, we expect to develop a novel class of NOPs with hierarchical pore structure but retaining enhanced microporosity. On the other side, the tunable nature and robust porous structure of NOPs may also be beneficial in mitigating environmental problems caused by toxic radiated iodine from medical waste and nuclear waste that could cause serious healthy problems due to its involvement in human metabolic processes and its long half-life. Very recently, NOPs have proved their great potential as excellent sorbents for volatile iodine removing[19-20]. The iodine uptake capacities are correlated with the specific high affinity binding sites through non-covalent bonds. Polar groups, conjugated units and large surface areas are considered to facilitate the enhancement of iodine adsorption[21-22]. Despite these success, developing versatile NOPs combining the functions for selective capature of CO2 and effective removal of iodine waste as well as their easy scal-up construction technology remains a contemporary field of materials and environmental chemistry. High rigid monomers, such as triptycene, spirobifluorene, tetraphenylmethane, adamtane and so on, are attractive components for the synthesis of polymers with enhanced intiristic microporosity because they can pack inefficiently in solid state. Especially, the tetrahedral building units have a predisposition to form networks with a diamondoid topology resulting in excellent thermodynamic stability, high surface areas

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

(PAF-1[23]: BET surface areas 5600 m2 g-1), and large gas storage capacity (130 wt%, 40 bar/298 K) polymers. Among them, 1,3,5,7-tetraphenyladamantane (TPA) is a superb building block for generating enhanced microporous architectures due to its highly symmetrical tetrahedral shape along with huge molecular volume and stiffness, and it can be easily functionalized and spread out further[24]. For synthetic methodology of NOPs, Friedel-Crafts (FC) alkylation and

Scholl coupling

polymerization have demonstrated certain advantages such as cheap catalyst, mild reaction condition and high yield, which are essential for scale-up preparation of NOPs with permanent porosity[25-27]. These have initiated our efforts to establish efficient and accessible NOPs with rigid tetrahedral building block based on such cost-effective strategies. Herein, we prepared a series of tetraphenyladamantane-base NOPs via low-cost versatile strategies. Such materials without relying on complicated reactions, high-cost catalyst, or specific functional groups, are significantly less expensive than other porous materials with similar structure, like conjugated microporous polymers (CMPs) prepared by rare metal catalyzed coupling reactions. Moreover, the incoporation of rigid and bulky tetraphenyladamantane ensures the generation of micropores, while flexible crosslinkers are expected to introduce mesopores and even macropores into the networks resulting in hierarchical pore structure. Such characteristics would lead to a novel series of intrinsically microporous materials similar in nature to the polymers with intrinsic microporosity (PIMs) but retaining the broad pore size distribution characteristics of common hypercrosslinked network polymers (HCPs). Small gases (CO2 and CH4 ) sorption capacities and selectivities were examined, and the capture of iodine vapors and iodine in the solution were further probed. The influence of varying

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

crosslinker on the pore structures and surface areas was investigated. This study provides simple methods for the preparation of hierarchical pore structure NOPs and highlights the importance of tetrahedral building block and hierarchical pore structure for both effective CO2 and iodine capture. (Figure.1) 2. Materials and methods 2.1. Materials 1,3,5,7-tetraphenyladamantane, dichloroxylene (DCX), formaldehyde dimethyl acetal (FDA) and Iodine were purchased from Alfa Aesar Chemical Inc. and used as received. Other chemicals and reagents were purchased from commercial suppliers without further purification unless otherwise stated. 1, 2-dichloroethane (DCE) was dehydrated with CaH2. 2.2. Characterization The FT-IR spectra were collected in transmission on a VARIAN 1000 FT-IR (scimitar series) spectrometer using KBr disks. Thermo-gravimetric analysis (TGA) was performed at a heating rate of 10 K/min under N2 atmosphere using a PERKIN ELMER TGA7. Solid-state

13

C CP/MAS (cross-polarization with magic angle spinning) spectra

were measured on a Bruker Avance

400 NMR spectrometer at 100.61 MHz at an

MAS rate of 5.0 kHz using zirconia rotors 4 mm in diameter using a contact time of 3.0 ms and a relaxation delay of 2.0 s. Scanning electron microscopy (SEM) imaging was performed on a JEOS JSM 6700. Transmission electron microscopy (TEM) was recorded using a JEOL JEM 3010 with an acceleration voltage of 300 kV. Inductively coupled plasma mass spectrometry (ICP-MS) was performed on a Agilent 7700e. The UV-vis adsorption spectra were measured using a Hitachi U-5100 spectrophotometer.

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

All the adsorption and desorption measurements for N2, CO2 and CH4 were performed on an Autosorb-iQ (Quantachrome) analyzer at selected temperatures. Low pressure N2 adsorption and desorption isotherms were measured at 273 K. The cumulative apparent surfaces areas for N2 were calculated using the Brunauer-Emmett-Teller (BET) model range from 0.01 to 0.10 bar for all samples. Microporous volumes were calculated using the t-plot method, while the total porous volumes were obtained from the N2 isotherm at P/P0= 0.99. Pore size distributions were derived from the N2 adsorption isotherms using NLDFT methods. CO2 adsorption isotherms were measured at 273 and 298 K up to 1 bar. 2.3. General procedure for the preparation of NOPs NOP-53: 1, 3, 5, 7- tetraphenyladamantane (0.8812 g, 2 mmol) and FeCl3 (3.8929 g, 24 mmol) were added to a dry 100 mL three-necked round-bottom flask equipped with a condenser and a mechanical agitation device. 30 mL anhydrous 1, 2-dichloroethane was injected into the aforementioned mixture under a flow of nitrogen. After 10 min of stirring, FDA (1.8264 g, 24 mmol) was charged. The resulting reaction mixture was heated to 45 oC for 5 h and then at 80 oC for another 19 h at constant stirring. After cooling to room temperature, the precipitate was collected by filtration and washed with methanol until the filtrate turned clear. The crude product was soxhlet extracted with methanol, chloroform, and dried in vacuum at 120 oC for 24 h. NOP-53 was obtained in a yield of 96 % as a high brown colored, powdery solid. NOP-54: 1, 3, 5, 7-tetraphenyladamantane (0.8812 g, 2 mmol) and DCX (4.200 g, 24 mmol) and FeCl3 (3.8929 g, 24 mmol) was added to a dry 100 mL three-necked roundbottom flask equipped with a condenser and a mechanical agitation device. 20 mL anhydrous 1,2-dichloroethane was injected into the aforementioned mixture under a

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

flow of nitrogen. The mixture was heated to 80 oC for 24 h under a nitrogen atmosphere at constant stirring. After cooling to room temperature, the precipitate was collected by filtration and washed with methanol until the filtrate turned clear. Further purification of the polymer was carried out by Soxhlet extraction with methanol and chloroform, and dried in vacuum at 120 °C for 24 h. NOP-54 was obtained in a yield of 95 % as a snuff colored, powdery solid. NOP-55: under N2 atmosphere, a 50 mL round-bottomed flask was charged with anhydrous AlCl3 (1.920 g, 14.4 mmol), 15 mL of anhydrous CHCl3 and a magnetic stirrer. After stirred and heated to 60 °C for 0.5 h, the resultant solution was treated dropwise with 1, 3, 5, 7-Tetraphenyladamantane (1.7624 g, 4 mmol) dissolved in anhydrous CHCl3 (15 mL). The mixture was stirred at 60 °C for 24 h and left to cool to room temperature. The solid was obtained by filtration and subsequently washed with chloroform, acetone and methanol to remove unreacted monomers. The product was then immersed and stirred in 3 M HCl and 3 M NaOH aqueous solution for 4 h, respectively, to remove catalyst residues. The crude product was soxhlet extracted with THF, methanol, acetone and chloroform and dried at 120 °C under vacuum to give NOP-55 as tan powder in a good yield of 94 %. 2.4. Iodine vapor sorption measurements Iodine uptakes were measured gravimetrically. Samples of a known weight were loaded into a small weighing bottles, which were located in a sealed container with iodine pellets kept at the bottom. The container was degassed and kept at 75

. Some

contact time later, the NOPs samples adsorbing iodine was cooled down to room temperature and weighed.The iodine uptake was determined at different time intervals. 3. Results and discussion

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

3.1. Characterization The successful growth of the as-synthesized microporous networks (Fig.1) had been characterized by fourier transform infrared (FT-IR) spectroscopy (Fig.S1), solid-state 13

CP/MAS NMR measurement (Fig.2) and elemental analysis (Table.S1). The signals at

1600 and 1450 cm-1 for skeleton vibrations of aromatic rings, are consistent with the structure of corresponding building blocks. For NOP-53 and NOP-54, the appearance at 2930 cm-1 for C-H stretching vibrations reveals that the blocks are linked by methylene groups as designed, implying the successful formation of the desired networks. While the diminution of the peaks at 750 cm-1 ascribe to the C-H deformation vibration of four adjacent phenyl rings in the corresponding building blocks, indicates the formation of crosslinked network of NOP-55[18]. Solid-state

13

CP/MAS NMR spectroscopy was

further used to study the structure of the polymers. In all the materials, peaks at 128 ppm – 149 ppm are ascribed to the substituted aromatic carbon and nonsubstituted aromatic carbon. In the spectra of NOP-53 and NOP-54, the resonance peaks at approximately 38 ppm, due to carbon in methylene linker formed after polymerization are in good consistent with the FT-IR analysis. Additionally, the quaternary carbon atom in NOP-55 can be confirmed by the peak at around 52 ppm. The ICP-MS experiments show that all the polymers do not contain Fe ions, thus suggesting that all the catalysts are successfully removed by the purification process. (Figure.2) The powdered XRD patterns (Fig.S2-S4) demonstrate that the resulting polymers are all in an amorphous phase. The morphology and textural nature of the NOPs were investigated by SEM and TEM (Fig.S5). As shown in a typical SEM image of NOP-53, the samples are composed of rough particles similar to other known HCP networks[28].

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Typically, for NOP-53 worm-like porous textures are visualized by HR-TEM images, and the investigated samples are featured with abundant microporosity. Sorbents with high stability would increase the possibility of recyclability and thus efficiently reduce the energy consumption and cost per cycle. Thermal gravimetric analyses demonstrate that all resultant networks are relatively stable up to 372 oC (temperature for 10 % mass loss) under a nitrogen atmosphere owing to their robust aromatic nature (Fig. S6). Slight weight loss is observed for all samples at the initial stages due to the trapped solvents and moisture inside[29], consistent with the broad bands at 3435 cm-1 for O-H stretch in the FT-IR spectra. It is worth mentioning that such polymers retain more than 54 % of their mass at temperatures of 800 oC. In addition, all polymers are chemically stable, even when exposed to dilute solutions of acid or base, such as HCl or NaOH as well as common organic solvents such as N, Ndimethylformamide (DMF), CHCl3, tetrahydrofuran (THF), etc., implying their high chemical stability. Such characteristics ensure that the obtained polymers could be developed to useful components under rigorous conditions. 3.2. Pore properties of NOPs As measured by nitrogen-sorption experiments at 77 K (Fig.3a), NOP-53 and NOP-54 display similar type I isotherms with mixed type IV characters according to the IUPAC classification. Their nitrogen adsorption-desorption isotherms exhibit sharp uptakes at low relative pressures (P/P0 < 0.03), indicating a microporous nature. The isotherms show a continuous increase after the adsorption at low relative pressure (0.03 < P/P0 < 0.1), indicative of the adsorption on the outer surface of small particles[30]. Additionally, the presence of small hysteresis in the N2 desorption curves suggests a partial mesoporous character of the polymers. Note that they have mild capillary

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

condensation over P/P0 of 0.90. This behavior is usually related to interstitial voids within the polymer powder and to the swelling effects of the network while coming in contact with the probing gas[31]. However, NOP-55 show a typical type I nitrogen gas sorption isotherm, indicating that it is a typical microporous material. The pore size distribution (Fig.3b) calculated by nonlocal density functional theory (NL-DFT) demonstrate that all investigated samples exhibit abundant microporosities with dominant pore diameters centered at approximately 0.60 nm, and the micropores pore size of NOP-53, NOP-54, and NOP-55 are also found to be located at 1.4, 1.3 and 1.0 nm, respectively. Certain mesoporosity at approximately 3.8 and 4.0 nm are demonstrated for NOP-53 and NOP-54, featuring a hierarchically porous structure, while NOP-55 is found to be solely microporous polymers with a broad micropore size distribution. These results are well consistent with the shape of the nitrogen isotherms. The high rigid building block with flexible alkyl chain appears to be favorable to the formation of interpenetrating pore structure, which lead to a novel series of intrinsically microporous materials while retaining the characteristics of common HCPs. Especially, for NOP-54 rigid and extended linkers presumably exist due to self-condensation of bischloromethyl monomers[32], which endows them with much broader PSDs feature including ultramicro-, micro-, meso-, and negligible macropores. (Figure.3) Pore parameters of the as-made networks are summarized in Table 1. The BET specific surface areas for NOP-53, NOP-54, and NOP-55 are 744, 1178, and 526 m2 g-1, respectively. The pore volume follows the similar trend of the surface area. NOP-54 exhibit the highest pore volume up to 1.32 cm3 g-1, followed by NOP-53 (0.73 cm3 g-1) and NOP-55 (0.42 cm3 g-1). Indeed, such parameters are lower than those of some

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

famous NOPs like COF-103 (4210 m2 g-1, 1.66 cm3 g-1) [33] and PAF-3 (2932 m2 g-1, 1.54 cm3 g-1) [34], but their surface areas and pore volume are comparable to those of most HCPs[35-36], and higher than the known HCP networks utilizing the same synthetic technology[17,37-38]. Such performance can be ascribed to the abundant microporous and hierarchical porous structure in the networks. The existence of benzyl chains and the possible extended rigid linker between the rigid tetrahedral building blocks in NOP-54 network may help to further frustrate the space-efficient packing of the polymer network, leading to greater microporosity and broader PSD, these are favorable to the formation of hierarchical porous structure. NOP-55 exhibit relative lower BET suface area and pore volume, which can be ascribed to its purely microporous characteristics. It can be concluded that the pore structure of the polymers can be tunable by variation of the crosslinkers. (Table. 1) 3.3. Gas storage and gas separation Because the obtained NOPs have large surface area, unique pore structure, high physic and chemical stabiltiy, these initiate our effort to apply such NOPs in CO2 capture. Shown in Fig. 4 are the CO2 adsorption isotherms at 273 K and 298 K. The NOPs exhibit moderate CO2 adsorption capacities ranging from 8.6 to 14.2 wt% at 273 K and 1.0 bar. Among them, NOP-54 exhibits the highest CO2 uptake due to its highest pore volume and abundant microporosity. Furthermore, the mesoporous in the NOP-54 can reduce the gas diffusion pathway and enhance pore accessibility. This result is comparable to tetraphenyladamantane-based polyimides PAN-1[39] (14.8 wt% at 1 bar/273 K), MOP-Ad-1[40] (10.3 wt% at 1.13 bar/273 K), and even some heterocyclicfunctional aromatic NOPs (eg, Th-1[41]: 12.7 wt% at 1 bar/273 K, Cz-POF-4[42]: 12.1

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

wt% at 1 bar/273 K), but also is much higher than most porous polymers with higher BET specific surface, such as PAF-1[23] (SBET = 5600 m2.g-1, 9.1 wt% at 1 bar/273 K) and COF-102[43] (SBET =3620 m2.g-1, 6.86 wt% at 1 bar/273 K). NOP-55 exhibits relative lower CO2 adsorption capacity, which can be ascribed to its solely microporous structure. It is difficult for gas molecules to enter the micropores and diffusion is inefficient[44]. These further indicate that the hierarchical pore structure is efficient for gas molecular transport and adsorption in the polymer networks by integrating the advantages of micropores and mesopores. The CO2 adsorption capacity at 298 K follows the same trend as those observed at 273 K. It is noteworthy that, at 298 K and 1 bar, the NOP-54 still has a high CO2 uptake of 8.0 wt%. This characteristic is very useful for the practical CO2-capture operation under ambient conditions. To probe the host-CO2 binding affinity, the isoseric heat of adsorption (Qst) was also calculated from the CO2 isotherms at 273 K and 298 K by using the Clausius-Clapeyron equation (Fig.S7). The heats of adsorption of CO2 at low loadings are 32, 40, and 28 kJ mol-1 for NOP-53, NOP-54, and NOP-55, respectively. These values are comparable to those reported for COFs[45-46], and even higher than many heterocyclic-functional aromatic NOPs, i.e., porous electron rich covalent organonitridic frameworks (PECONFs: 26-34 kJ mol-1) [47], triazine polyimides (TPIs: 30-35 kJ mol-1) [48]. Such results demostrate that abundant micropores significantly enhance the interactions between the network and CO2 molecular. The initially decreasing and then almost stabilizing trend of the Qst suggests that high energy sites are occupied first and then the adsorption reaches a saturation lever after a certain amount of CO2 uptake. However, it’s worth noting that the values of the heat of adsorption remain well below the energy of the chemical

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

adsorption (< 50 kJ mol-1), thus indicating that CO2 adsorption is physical in nature, which is highly desirable for facile CO2 release. (Figure.4) CH4 is an important potential alternative clean fuels for the next generation of automotive technology, the CH4 uptake capacities of the polymers at 273 K/1 bar were further probed (Fig.S8). According to the pore properties of the polymers, CH4 adsorption follows the same sequence as described for CO2. NOP-54 show the largest CH4 uptake (1.32 wt%), followed by NOP-53 (1.12 wt%) and NOP-55 (0.78 wt). Such values could be compared to the common NOPs, such as BF[49] (1.22 wt%), PCBZL[50] (1.08 wt%) , and NPOF-4-NH2[51] (1.25 wt%). (Figure.5) In addition to the CO2 adsorption capacity and reversibility, a high selectivity for CO2 over other gases such as N2 and CH4, is one of the key requirements for CO2 capture application. Selective adsorption of these polymer networks for different gases were calculated using ideal adsorbed solution theory (IAST) model at 273 K and up to 1 bar ( Fig.S9 and Fig.5). The CO2/N2 selectivities are 36, 56, and 42 for NOP-53, NOP-54, and NOP-55, respectively. Although these values are lower than those of porous polymers bearing polar functional groups, such as Azo-COP-2 (110) [52], Pyrrole-HCP (117) [40], the results are competitive comparing to the aniline-based HCPs[53], and polyimides SMPI-0 (30) [54]. While the values of CO2/CH4 selectivities are 12.3, 13.9 and 10.8 for NOP-53, NOP-54 and NOP-55, respectively. These results are better than many reported materials with CO2/CH4 selectivity ratios, i.e., PI-NO2-1 (11) [55], PAN1 (10) [38], and BILP-1 (10) [56]. It is clear that the CO2 over N2 and CH4 selectivities increase as the pore size decrease or pore volume increase. The reason may be attributed

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

to that CO2 molecule having the smaller kinetic diameter (3.30 Å) than N2 (3.64 Å) and CH4 (3.80 Å), We can therefore attribute the good ideal CO2/N2 and CO2/CH4 selectivities to the high fraction of micropores and ultramicropores (below 1.0 nm), which can provide strong interaction towards small gas molecules. 3.4. Iodine capture and adsorption by NOPs Herein, the efficacy of the obtained NOPs as iodine adsorbents were further probed. An apparent color change from brown to black are observed (Fig.S10). The results indicate that the iodine uptake increase gradually over the 4 h and reached a plateau (Fig.6). The iodine loading show little change after 24 h, suggesting that the system is saturated. At low coverage, an effective binding site is crucial, thus leading to the high interaction with iodine molecules, while the total uptakes are mainly influenced by the surface area and pore volume at higher coverage[57]. Therefore, NOP-54 with abudant micropores and highest pore volume exhibit the highest iodine uptake up to 202 wt%, followed by NOP-53 (177 wt%) and NOP-55 (139 wt%). Under the same condition, such results are lower than that of some polymers with high affinity functional groups (Azo-Trip[58]: 238 wt%, HCMP-3[20]: 316 wt%, AzoPPN[59]: 290 wt%, SCMP[21]: 345 wt%), but can be comparable to some conjugated microporous polymers (CMPN-3[60]: 208 wt%, CMP-E1[61]: 215 wt%, NIP-CMP[22]: 202 wt%, SCMP1[62]: 188 wt%)，and are even higher than that with larger surface areas (PAF-1[57]: 186 wt%) and metal organic frameworks (ZIF-8[63]: 125 wt%). The iodine capture capability of NOPs was further investigated in organic solution. After NOPs of the same weight were immersed in an iodine-hexane solution, the dark purple solutions of I2 fade slowly to deep red and then to very pale red (Fig.S11). UV/vis spectroscopy was used to characterize the adsorption kinetic of iodine (Fig. 7 and Fig.S12-S13). It can be seen

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

that two stages of adsorption kinetics were obtained: the adsorption capacity for iodine increased quickly during the first 240 min, and after that low increase was observed until equilibrium was reached. NOP-54 exhibits the highest iodine adsorption capacity up to 89 %, followed by NOP-53 (86 %) and NOP-55 (81 %), which are consistent with the trend of microporosity. Additionally, NOP-53 and NOP-54 not only adsorb iodine with higher capacity but also show faster adsorption rate than those of NOP-55, which can be attributed to the existence of hierarchical porous structure facilitating the transport of iodine in the networks. Such results further prove that high suface area, open porous structures and strong affinity of absorbents to iodine molecules would lead to an increase in iodine capture. (Figure.6 and Figure.7) 4. Conclusions In summary, a series of tetraphenyladamantane-based hierarchically porous organic polymers were easily synthesized via Friedel-Crafts and Scholl couping reaction. The BET suface areas of the polymers are in the range 526 -1178 m2 g-1, and substantially improved pore volumes up to 1.32 cm3 g-1 are obtained. The polymers, which are derived from high rigid tetraphenyladamantane building blocks, pack inefficiently in the solid state providing the materials with high microporosity and a competitive CO2 uptake ability of 14.2 wt% (1 bar and 273 K) and moderate absorption capacity for methane (1.32 wt% at 273 K and 1 bar) are demostrated. High selective adsorption of CO2 over N2 (56) and CH4 (13.9) at 273 K are also achieved. Moreover, the obtained NOPs exhibit potential application in iodine adsorption, its capacity is up to 202 wt% due to the abduant microprosity. This work offer a convenient way to construct highly

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

stable polymer networks with greater microprous and hierarchically porous structure for efficient small gases (CO2 and CH4) and iodine capture. Acknowledgements We acknowledge the financially support from the National Science Foundation of China (Nos. 21204103 and 21376272), Hunan Nature Science-Zhuzhou Joint Foundation (2015JJ5015), State Key Laboratory of Fine Chemicals (KF1206) and the Hunan Provincial Science and Technology Plan Project, China (No.2016TP1007). Appendix A. Supplementary data Supplementary data associated with this article can be found in the online version, at http://dx.doi.org/10.1016/j.cej. References [1]

A. F. Bushell, P. M. Budd, M. P. Attfiedld, J. T. A. Jones, T. Hasell, A. I. Cooper, P. Bernardo, F. Bazzarellli, G. Clarizia, J. C. Jansen, Nanoporous organic polymer/cage composite membranes. Angew. Chem. Int. Ed. 52(2013)1253-1256.

[2]

B. S. Ghanem, R. Swaidan, E. Litwiller, I. Pinnau, Ultra-microporous triptycen-based polyimide membranes for high-performance gas separation, Adv. Mater. 26(2014) 3688-3692.

[3]

Y. Liu, S. F. Wu, G. Wang, G. P. Yu, J. G. Guan, C. Y Pan , Z. G Wang,

Control of porosity of novel carbazole-modified polytriazine frameworks for highly selective separation of CO2-N2, J. Mater. Chem. A. 2(2014) 7795-7801. [4]

S. Nandi, S. K. Singh, D. Mullangi, R. Illathvalappil, L. George, C. P. Vinod,

S. Kurungot, R. Vaidhyanathan, Low band gap benzimidazole COF supported Ni3N as highly active OER catalyst, Adv. Energy Mater. 6(2016) 1601189.

17

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[5]

Z. Y. Fu, J. Z. Jia, J. Li, C. K. Liu, Transforming waste expanded

polystyrene foam into hyper-crosslinked polymers for carbon dioxide capture and separation, Chem. Eng. J. 323(2017) 557-564. [6]

L. Hao, J. Ning, B. Luo, B. Wang, Y. B. Zhang, Z. H. Tang, J. H. Yang, A.

Thomas, L. J. Zhi, Structural evolution of 2D microporous covalent trizine-based framework toward the study of high-performance supercapacitors, J. Am. Chem. Soc. 137(2015) 219-225. [7]

V. Presser, J. Mcdonough, S. Yeon, Y. Gogotsi, Effect of pore size on

carbon dioxide sorption by carbide derived carbon, Energy Environ. Sci. 4(2011) 3059-3066. [8]

F. Raganati, P. Ammendola, R. Chirone, CO2 capture performances of fine

solid sorbents in a sound-assisted fluidized bed, Powder Technol. 268(2014) 347-356. [9]

P. Ammendola, F. Raganati, R. Chirone, Effect of operating conditions on

the CO2 recovery from a fine activated carbon by means of TSA in a fluidized bed assisted by acoustic fields, Fuel Process Technol. 134(2015) 494-501. [10]

Y. Liu, J. Wilcox, Molecular simulation of CO2 adsorption in micro- and

mesoporous carbons with surface heterogeneity, Int. J. Coal Geol. 104(2012) 8395. [11]

F. Raganati, P. Ammendola, R. Chirone, Effect of acoustic field on CO2

desorption in a fluidized bed of fine activated carbon, Particuology. 23(2015) 815.

18

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[12]

M. Sevilla, J. B. Parra, A. B. Fuertes, Assessment of the role of micropore

size and N-doping in CO2 capture by porous carbons, ACS Appl. Mater. Interfaces. 5 (2013) 6360-6368. [13]

F. Raganati, P. Ammendola, R. Chirone, On improving the CO2 recovery

efficiency of a conventional TSA process in a sound assisted fluidized bed by separating heating and purging, Sep. Purif. Technol. 167 (2016) 24-31. [14]

P. Ammendola, F. Raganati, R.Chirone, CO2 adsorption on a fine activated

carbon in a sound assisted fluidized bed: Thermodynamics and kinetics. Chem Eng J. 322(2017) 302-313. [15]

S. Y. Lee, S. J. Park, Carbon dioxide adsorption performance of

ultramicroporous carbon derived from poly(vinylidene fluoride), J. Anal. Appl. Pyrolysis. 106 (2014) 147-151. [16]

S. J. Yang, T. Kim, J. H. Im, Y. S. Kim, K. Lee, H. Jung, C. R. Park, MOF-

derived hierarchically porous carbon with exceptional porosity and hydrogen storage capacity, Chem. Mater. 24(2012) 464-470. [17]

A. Modak, Y. Maegawa, Y. Goto, S. Inagaki, Synthesis of 9,9’-

spirobifluorene-based conjugated microporous polymers by FeCl3-mediated polymerization, Polym. Chem. 7(2016) 1290-1296. [18]

S. Gu, J. Q. He, Y. L. Zhu, Z. Q. Wang, D. Y. Chen, G. P. Yu, C. Y. Pan, J.

G. Guan, K. Tao, Facile carbonization of microporous organic polymers into hierarchically porous carbons targeted for effective CO2 uptake at low pressures, ACS Appl. Mater. Interfaces. 8(2016) 18383-18392. [19]

Y. X. Lin, X. F. Jiang, S. T. Kim, S. B. Alahakoon, X. S. Hou, Z. Y. Zhang,

C. M. Thompson, R. A. Smaldone, C. F. Ke, An elastic hydrogen-bonded cross-

19

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

linked organic framework for effective iodine capture in water, J. Am. Chem. Soc. 139(2017) 7172-7175. [20]

Y. Z. Liao, J. Weber, B. M. Mills, Z. H. Ren, C. F. J. Faul, Highly efficient

and

reversible

iodine

capture

in

hexaphenylbenzene-based

conjugated

microporous polymers, Macromolecules. 49(2016) 6322-6333. [21]

F. Ren, Z. Q. Zhu, X. Qian, W. D. Liang, P. Mu, H. X. Sun, J. H. Liu, A. Li,

Novel thiophene-bearing conjugated microporous polymer honeycomb-like porous spheres with ultrahigh iodine uptake, Chem. Commun. 52(2016) 97979800. [22]

S. G. A, Y. W. Zhang, Z. P. Li, H. Xia, M. Xue, X. M. Liu, Y. Mu, Highly

efficient and reversible iodine capture using a metalloporphyrin-based conjugated microporous polymer, Chem. Commun. 50(2014) 8495-8498. [23]

T. Ben, H. Ren, S. Q. Ma, D. P. Cao, J. H. Lan, X. F. Jing, W. H. Wang, J.

Xu, F. Deng, J. M. Simmons, S. L. Qiu, G . S. Zhu, Targeted synthesis of a porous aromatic framework with high stability and exceptionally high surface area, Angew. Chem. 121(2009) 9621-9624. [24]

C. J. Shen, Y. J. Bao, Z. G. Wang, Tetraphenyladamantane-based

microporous polyimide for adsorption of carbon dioxide, hydrogen, organic and water vapors, Chem. Commun. 49(2013) 3321-3323. [25]

J. Germain, J. M. J. Frechet, F.Svec, Nanoporous, hypercrosslinked

polypyrroles: effect of crosslinking moiety on pore size and selective gas adsorption, Chem. Commun. 12(2009) 1526-1528. [26] B. Y. Li, R. N. Gong, W. Wang, X. Huang, W. Zhang, H. M. Li, C. X. Hu, B. E. Tan, A new strategy to microporous polymers: knitting rigid aromatic

20

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

building blocks by external cross-linker, Macromolecules. 44(2011) 24102414. [27]

P. Puthiaraj, Y. R. Lee, W. S. Ahn, Microporous amine-functionalized

aromatic polymers and their carbonized products for CO2 adsorption, Chem. Eng. J. 319(2017) 65-74. [28]

C. Zhang, P. C. Zhu, L. X. Tan, J. M. Liu, B. E. Tan, X. L. Yang, H. B. Xu,

Triptycene-based hyper-cross-linked polymer sponge for gas storage and water treatment, Macromolecules. 48(2015) 8509-8514. [29]

H. A. Patel, S. H. Je, J. Park, D. P. Chen, Y. Jung, C. T. Yavuz, A. Coskun,

Unprecedented high-temperature CO2 selectivity in N2-phobic nanoporous covalent organic polymers, Nat. commun. 4(2013) 1357-1365. [30]

J. H. Zhu, Q. Chen, Z. Y. Sui, L. Pan, J. Yu, B. H. Han, Preparation and

adsorption performance of cross-linked porous polycarbazoles, J. Mater. Chem. A. 2(2014) 16181-16189. [31]

P. Katekomol, J. Roeser, M. Bojdys, J. Weber, A. Thomas, Covalent triazine

frameworks prepared from 1,3,5-tricyanobenzene, Chem Mater. 25(2013) 15421548. [32]

C. D. Wu, B. E. Tan, A. Trewin, H. J. Niu, D. Bradshaw, M. J. Rosseinsky, Y.

Z. Khimyark, N. L. Campbell, R. Kirk, E. Stockel, A. I. Cooper, Hydrogen storage in microporous hypercrosslinked organic polymer networks, Chem. Mater. 19(2007) 2034-2048. [33]

H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortes, A. P. Cote, R. E. Taylor,

M. O’Keefe, O. M Yaghi, Designed synthesis of 3D covalent organic frameworks, Science. 316(2007) 268-272.

21

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[34]

T. Ben, C. Y. Pei, D.L. Zhang, J. Xu, F. Deng, X. F. Jing, S. L. Qiu, Gas

storage in porous aromatic frameworks (PAFs), Energy Environ. Sci. 4(2011) 3991-3999. [35]

L. Pan, Q. Chen, J. H. Zhu, J. G. Yu, Y. J. He, B. H. Han, Hypercrosslinked

porous polycarbazoles via one-step oxidative coupling reaction and FriedelCrafts alkylation, Polym. Chem. 6(2015) 2478-2487. [36]

M. Seo, S. Kim, J. Oh, S. J. Kim, M. A. Hillmyer, Hierarchically porous

polymers from hyper-cross-linked block polymer precursors, J. Am. Chem. Soc. 137(2015) 600-603. [37]

S. W. Yao, X. Yang, M, Yu, Y. H. Zhang, J. X. Jiang, High surface area

hypercrosslinked

microporous

organic

polymer

networks

based

on

tetraphenylethylene for CO2 capture, J. Mater. Chem. A. 2(2014) 8054-8059. [38]

X. Zhu, S.M. Mahurin, S. H. An, C. L. Do-Thanh, C. C. Tian, Y. K. Li, L. W.

Gill, E. W. Hagaman, Z. J. Bian, J. H. Zhou, J. Hu, H. L. Liu, S. Dai, Efficient CO2 capture by a task-specific porous organic polymer bifunctionalized with carbazole and triazine groups, Chem. Commun. 50(2014) 7933-7936. [39]

G. Y. Li, B. Zhang, J. Yan, Z. G. Wang, Tetraphenyladamantane-based

polyaminals for highly efficient captures of CO2 and organic vapors, Macromolecules. 47(2014) 6664-6670. [40]

X. Li, J. W. Guo, H. B. Yue, J. W. Wang, P. D. Topham, Synthesis of

thermochemically stable tetraphenyladamantane-based microporous polymers as gas storage materials, RSC Adv. 7(2017) 16174-16180.

22

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[41]

Y. L. Luo, B. Y. Li, W. Wang, K. B. Wu, B. E. Tan, Hypercrosslinked

aromatic heterocyclic microporous polymers: a new class of highly selective CO2 capturing materials, Adv. Mater. 24(2012) 5703-5707. [42]

X. Zhang, J. Z. Lu, J. Zhang, Porosity enhancement of carbazolic porous

organic frameworks using dendritic building blocks for gas storage and separation, Chem. Mater. 26(2014) 4023-4029. [43]

H. Furukawa, O. M. Yaghi, Storage of hydrogen, methane, and carbon

dioxide in highly porous covalent organic frameworks for clean energy applications, J. Am. Chem. Soc. 131(2009) 8875-8883. [44]

G. Srinivas, V. Krungleviciute, Z. X. Guo, T. Yildirim, Exceptional CO2

capture in a hierarchically porous carbon with simultaneous high surface area and pore volume, Energy Environ. Sci. 7(2014) 335-342. [45]

R. Gomes, P. Bhanja, A. Bhaumik, A triazine-based covalent organic

polymer for efficient CO2 adsorption, Chem. Commun. 51(2015) 10050-10053. [46]

A. P. Cote, H. M. El-Kaderi, H. Furukawa, J. R. Hunt, O. M. Yaghi,

Reticular synthesis of microporous and mesoporous 2D covalent organic frameworks, J. Am. Chem. Soc. 129(2007) 12914-12915. [47]

P. Mohanty, L. D Kull, K. Landskron, Porous covalent electron-rich

organonitridic frameworks as highly selective sorbents for methane and carbon dioxide, Nat. Commun. 2(2011) 401−406. [48]

M. R. Liebl, J. Senker, Microporous functionalized triazine-based

polyimides with high CO2 capture capacity, Chem. Mater. 25(2013) 970−980.

23

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[49]

M. Saleh, H. M. Lee, K. C. Kemp, K. S. Kim, Highly stable CO2/N2 and

CO2/CH4 selectivity in hyper-cross-linked heterocyclic porous polymers, ACS Appl. Mater. Interfaces. 6(2014) 7325−7333. [50]

M. Saleh, S. B. Baek, H. M. Lee, K. S. Kim, Triazine-based microporous

polymers for selective adsorption of CO2, J. Phys. Chem. C. 119(2015) 53955402. [51]

T. Islamoglu, M. G. Rabbani, H. M. El-Kaderi, Impact of post-synthesis

modification of nanoporous organic frameworks on small gas uptake and selective CO2 capture, J. Mater. Chem. A. 1(2013) 10259-10266. [52]

H. A. Patel, S. H. Je, J. Park, Y. Jung, A. Coskun, C. T. Yavuz, Directing the

Structural Features of N2-Phobic Nanoporous Covalent Organic Polymers for CO2 Capture and Separation, Chem.-Eur. J. 20(2014) 772-780. [53]

R. Dawson, T. Ratvijitvech, M. Corker, A. Laybourn, Y. Z. Khimyak, A. I.

Cooper, D. J. Adams, Microporous copolymers for increased gas selectivity, J. Polym. Chem. 3(2012) 2034-2038. [54]

Y. Yang, Q. Zhang, Z. Zhang, S. Zhang, Functional microporous polymides

based on sulfonated binaphthalene dianhydride for uptake and separation of carbon dioxide and vapors, J. Mater. Chem. A. 1(2013) 10368-10374. [55]

C. J. Shen, Z. G. Wang, Tetraphenyladamantane-based microporous

polyimide and its nitro-functionalization for highly efficient CO2 capture, J. Phys. Chem. C. 118(2014) 17585-17593. [56]

M. G. Rabbani, H. M. El-Kaderi, Template-free synthesis of a highly porous

benzimidazole-linked polymer for CO2 capture and H2 storage, Chem. Mater. 23(2011) 1650-1653.

24

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

[57]

C. Y. Pei, T. Ben, S. X. Xu, S. L. Qiu, Ultrahigh iodine adsorption in porous

organic frameworks, J. Mater. Chem. A. 2(2014) 7179-7187. [58]

Q. Q. Dang, X. M. Wang, Y. F. Zhang, X. M. Zhang, An azo-linked porous

triptycene network as an absorbent for CO2 and iodine uptake, Polym. Chem. 7(2016) 643-647. [59]

H. Li, X. S. Ding, B. H. Han, Porous azo-bridged porphyrin-phthalocyanine

network with high iodine capture capability, Chem. Eur, J. 22(2016) 1186311868. [60]

Y. F. Chen, H. X. Sun, R. X. Yang, T. T. Wang, C. J. Pei, Z. T. Xiang, Z. Q.

Zhu, W. D. Liang, A. Li, W. Q. Deng, Synthesis of conjugated microporous polymer nanotubes with large surface areas as absorbnets for iodine and CO2 uptake, J. Mater. Chem. A. 3(2015) 87-91. [61]

Z. J. Yan, Y. Yuan, Y. Y. Tian, D. Zhang, G. S. Zhu, Highly efficient

enrichment of volatile iodine by charged porous aromatic frameworks with three sorption sites, Angew. Chem. Int. Ed. 54(2015) 12733-12737. [62]

X. Qian, Z. Q. Zhu, H. X. Sun, F. Ren, P. Mu, W. D. Liang, L. H. Chen, A.

Li, Capture and reversible storage of volatile iodine by nobel conjugated microporous polymers containing thiophene units, ACS Appl. Mater. Interfaces. 8(2016) 21063-21069. [63]

D. F. Sava, M. A. Rodriguez, K. W. Chapman, P. J. Chupas, J. A.

Greathouse, P. S. Crozier, T. M. Nenoff, Capture of volatile iodine, a gaseous fission product, by zeolitic imidazolate framework-8, J. Am. Chem. Soc. 133(2011) 12398-12401.

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Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig. 1. Schemtic presentation for the synthesis of NOPs.

O

O

FeCl3 , DCE NOP-53

Cl Cl

FeCl3, DCE

(

)

NOP-54

Scholl coupling

AlCl3, CHCl3

NOP-55

26

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig. 2. 13C CP/MAS NMR spectra of NOPs. Asterisks denote spinning sidebands.

27

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig.3. (a) Nitrogen adsorption/desorption isotherms at 77 K. (Adsorption: filled symbols; Desorption: open symbols). (b) pore size distribution curves calculated by NL-DFT method.

28

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig.4. CO2 adsorption insotherms collected at 273 K and 298 K

29

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig.5. IAST method for CO2 over N2 and CH4 selectivities for NOPs.

30

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig. 6. Iodine uptake curves for NOPs at 348 K

31

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Fig.7. (a) UV-vis spectra of NOP-53 (20 mg) after different contact time periods over iodine (1 mmol L-1) in hexane solution. (b) Iodine removal efficiency over iodine (1 mmol L-1) in hexane solution at diverse time periods.

32

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal

Table1. Porosity Properties and Gas Uptake Capacities of Polymers Polymers

SBET a (m2 g-1)

VMicro (cm3 g-1)

Vtotal b (cm3 g1 )

NOP-53

744

0.49

NOP-54

1178

NOP-55

Dominant pore diameter c (nm)

CO2 uptake d (wt.%)

Ref.

0.73

0.55, 1.42, 3.76, 4.03

10.1

0.86

1.32

0.58,1.28, 3.95

14.2

526

0.30

0.42

0.72, 1.03, 1.78

8.6

Chlorobenzene

438

0.16

0.36

-

5.5

This work This work This work [26]

CPOP-14

820

-

0.42

0.63,0.66

15.9

[30]

COP-3C

940

0.5

-

0.6-1.2

9.24

[17]

network-7

618

0.25

0.43

1.65

8.3

[37]

TSP-1

562

-

0.33

0.82,2.3

13.2

[38]

a

Specific surface area calculated from the nitrogen adsorption isotherm using the BET method; b Total pore volume at P/P0 =0.97; c Data calculated from nitrogen adsorption isotherms with the NL-DFT method; d Data were obtained at 1.0 bar and 273 K.

33

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal




The hierarchically porous Adamantanebased polymers achieve improved microporosity.




The porosities are well-controllable by regulating the lengths of linkers.




The polymers display efficient adsorption performance toward CO2 and iodine vapo ur.

34

Adamantane-based Porous Polymers for CO2 Capture and Iodine Removal