## 4 Conclusions  
A feasibility study on the design and synthesis of POP supports with a tunable pore structure and high performance of ethylene polymerization was conducted by the selection of functional comonomers, template agent, and control of the cross-linking degree of their frameworks. Functional porous organic polymers with a tunable pore structure and varied particle morphology were designed and synthesized, and the pore-size distributions of POPs are generally wider than the crystalline polymers, and the micropores and the mesopores could be tuned at the same time by the dispersion polymerization method. A single functional comonomer or dual comonomers in the PDVB-based POPs played a significant role in the porous structure and particle morphology of the prepared polymers, and different N\({}_{2}\) isotherms and pore structure with SSA of 10-450 m\({}^{2}\)/g, PV of 0.05-0.5 cm\({}^{3}\)/g, and bulk density with a range of 0.02-0.40 g/cm\({}^{3}\) were obtained by the varied functional POPs, mainly due to their different functional groups and thermodynamic compatibility with the selected solvent system. Furthermore, the Fe\({}_{3}\)O\({}_{4}\) nanoaggregates as a template agent could improve the porous structure and bulk density of the prepared POPs, and the highly cross-linking networks can dramatically increase the porous structure of the prepared POPs. The pore structure of the prepared POPs had a profound influence on the loading amount of the Zr and Al of the active sites, and the typically highly porous structure of the POPs would contribute the immobilization of the active species. High ethylene-polymerization activities of 8033 and 7152 kg PE/mol Zr h bar were  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**No.**} & **Zr** & **Cat** & **Al/Zr** & **Molar** & **Yield** & **Activity Kg** & **Productivity** & **Bulk Density** \\  & **(μmol/g)** & **(mg)** & **Ratio** & **(g)** & **PE/mol Zr h bar** & **g PE/g cat h** & **g/mL** \\ \hline S4 & 15.6 & 208 & 272 & 39.1 & 8033 & 376 & 0.30 \\ S5 & 2.3 & 192 & 179 & 1.45 & 2189 & 15.1 & 0.11 \\ S12 & 0.6 & 184 & 247 & - & - & - & - \\ S14 & 16.7 & 211 & 254 & 37.8 & 7152 & 358 & 0.29 \\ \hline \end{tabular}  
* * Slurry polymerization condition: 3 bar ethylene pressure in 800 mL reactor of stainless steel, 350 mL hexane, 80 °C, 2 mL (1 M in hexane) TIBA (scavenger), polymerization time: 30 min.  
\end{table}
Table 2: Ethylene polymerization results (catalyst: (n-BuCp)\({}_{2}\)ZrCl\({}_{2}\)/MAO@POPs) *b.  
achieved on the POPs-supported catalysts, especially when high Al/Zr ratios on the catalysts were obtained. By replicating the effect, the produced PE obtained higher bulk densities from the POPs with higher bulk densities. Therefore, it is a facile and practical approach to tailor the active sites of the metallocene catalysts and polyolefin particle morphology through the design of pore structure and surface morphology of the prepared POPs.  
[PERSON] conceived and designed the experiments; [PERSON], [PERSON], [PERSON], and [PERSON] performed the experiments; [PERSON], [PERSON], [PERSON], and [PERSON] analyzed the data; [PERSON] wrote the paper.  
This research received no external funding.  
This work was financially supported by PetroChina Company Limited.  
The authors declare no conflict of interest.