## 4 Conclusions  
Poly(S/DVB)HIPEs were successfully prepared from high internal phase emulsions technique and improved the property using difference ratio of DVB in organic phase. The obtained poly(S/DVB)HIPEs have an open cell structure with an average diameter of 79.4, 58.8, and 41.2 \(\upmu\)m and a surface area of 22, 189, and 363 m\({}^{2}\)/g for S/DVB at 80:20, 20:80, and 0:100, respectively. Moreover, increasing the concentration of divinylbenzene, the thermal degradation temperature of the poly(S/DVB)HIPE increased from 372 to 440 \({}^{\circ}\)C and the compressive strength increased from 0.13 to 0.30 MPa. Subsequently, poly(S/DVB)HIPE became more stable. In addition, poly(S/DVB)HIPEs were completely modified on the surface with the layer-by-layer polyelectrolyte multilayer (LbL) technique. Poly(S/DVB)HIPE modified by primary coating at three bilayers and PEI terminated as the secondary coating with high amounts of DVB (S/DVB: 0:100) in monomer ratio is the best surface modification to increase the CO\({}_{2}\) adsorption capacity up to 42% (from 0.71 to 1.01 mmol/g), when compared with the unmodified poly(S/DVB)HIPE. Compared to unmodified poly(S/DVB)HIPE, PEI modified poly(S/DVB)HIPE illustrated the highest CO\({}_{2}\) adsorption capacity due to the ability of chemical and physical adsorption. Results from modified poly(S/DVB)HIPE suggested that it has high adsorption capacity, can easily desorb, and has low energy of desorption and low cost of adsorption-desorption materials.  
Conceptualization, M.I.A., J.C., J.P., P.S. and M.N.; methodology, M.I.A., J.C., J.P., P.S. and M.N.; validation, M.I.A., J.C., J.P., P.S. and M.N.; formal analysis, M.I.A., J.C., J.P., P.S. and M.N.; investigation, M.I.A., J.C., J.P., P.S. and M.N.; resources, M.I.A. and M.N.; data curation, M.I.A., J.C., J.P., P.S. and M.N.; writing--original draft preparation, M.I.A., J.C. and J.P.; writing--review and editing, M.I.A., J.C., J.P., P.S. and M.N.; visualization, M.I.A., J.C., J.P., P.S. and M.N.; supervision, M.N.; project administration, P.S.; funding acquisition, M.I.A. and M.N. All authors have read and agreed to the published version of the manuscript.  
This research was funded by ASEAN scholarship, Chulalongkorn University.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{3}{*}{**(S/DVB)**} & \multicolumn{2}{c}{**Mass Fraction of Nitrogen (\%)**} & \multicolumn{2}{c}{**Adsorption Capacity (mmol/g)**} \\ \cline{2-6}  & **Modified** & **Modified** & **Unmodified** & **Modified** & **Modified** \\
**Ratio** & **polyHIPE** & **polyHIPE** & **Surface** & **polyHIPE** & **polyHIPE** \\
0:100 & 0.81 & 1.54 & 0.71 \(\pm\) 0.19 & 1.01 \(\pm\) 0.27 & 0.72 \(\pm\) 0.11 \\
20:80 & 0.59 & 0.52 & 0.64 \(\pm\) 0.12 & 0.82 \(\pm\) 0.62 & 0.72 \(\pm\) 0.13 \\
80:20 & 0.52 & 0.56 & 0.63 \(\pm\) 0.15 & 0.68 \(\pm\) 0.16 & 0.64 \(\pm\) 0.04 \\ \hline \hline \end{tabular}
\end{table}
Table 2: CO\({}_{2}\) adsorption of poly(S/DVB)HIPE between the unmodified and amine-modified surface.  
\begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Materials**} & \multicolumn{2}{c}{**CO\({}_{2}\) Adsorption Capacity**} & \multirow{2}{*}{**Ref.**} \\  & & **(mmol/g)** & \\ \hline polyHIPE & 0.71 \(\pm\) 0.19 & This paper \\ \hline Modified polyHIPE with PEI & 1.01 \(\pm\) 0.27 & This paper \\ \hline Modified polyHIPE with TETA & 0.72 \(\pm\) 0.11 & This paper \\ \hline Natural bentonite clay & 0.15 mmol/g & [28] \\ \hline Acid- natural bentonite clay & 0.38 mmol/g & [28] \\ \hline Activated carbon prepared from lawn grass & 0.12 mmol/g & [11] \\ \hline Ionic liquids & 4.72 mol of CO\({}_{2}\)/mol of solvent & [7] \\ \hline Deep eutectic solvents & 4.29 g CO\({}_{2}\) per g of solvent & [7] \\ \hline Liquid polymers & 1.36 mol of CO\({}_{2}\)/mol of solvent & [7] \\ \hline \hline \end{tabular}
\end{table}
Table 3: CO\({}_{2}\) adsorption with different materials.