## 3 Results and Discussion
### Characterization of Polymeric Adsorbents (VPM and HVPM)  
The microscope images of VBC-DVB copolymer beads (VPM) and hypercrosslinked beads (HVPM) are presented in Figure 4. Figure 4a is the image of pure VBC-DVB copolymer beads without embedded microcapsules. The beads are transparent, indicating scarcity of micropores. Figure 4b,c are the images of VPM and a cross-section profile of one randomly-chosen bead. As shown in the images, microcapsules are not only dispersed outside the polymeric adsorbents but are also embedded inside. Figure 4d presents the image of HPVM. The color turns brown and opaque because of the mixing of FeCl\({}_{3}\) into the micropore-dominant structure. For the final products, the average diameter is around 1.5-2.0 mm. The number of microcapsules on each bead is around 40. These characteristics are provided with good heat-storage capability because of a considerable amount of encapsulated wax through the microcapsules. Figure 5 presents the FTIR of VPM and HVPM. The sharp peak at 1265 cm\({}^{-1}\) indicates the presence of a CH\({}_{2}\)-Cl group from VBC. In the IR spectra obtained for HVPM, the characteristic peak almost disappeared, due to the inner bridging of the polymer beads. CH\({}_{2}\)-Cl groups are connected, resulting in large amounts of micro/mesopores. The spectra prove the completion of post-crosslinking reaction. The N\({}_{2}\) adsorption-desorption isotherms of polymeric adsorbents without post-crosslinking reaction  
Figure 4: Microscope images of **(a)** Vinylbenzyl chloride-Divinylbenzene (VBC-DVB) copolymer; **(b)** VBC-DVB copolymer embedded with microcapsules (VPM); **(c)** Cross-section profile of one polymer bead; **(d)** Hypercrosslinked VBC-DVB copolymer embedded with microcapsules (HVPM). Figure 3: Scanning electron micrographs of **(a)** DVB-wax microcapsules; **(b)** higher resolution image of one randomly chosen microcapsule. (VPM) also proves the above conclusion. The isotherm is not shown because it has almost no sign of gas adsorption and the reason is that VPM is mainly composed of mesopores and macropores before the post-crosslinking reaction. The DSC results for pure wax, microcapsules, and polymer beads are shown in Figure 6 and Table 1. The fusion heat of microcapsules is 33.8 J/g and the counterpart for polymer beads is 11.1 J/g. It suggests that the percentage of microcapsules in polymer beads is around 32.8%, which corresponds to the high percentage of embedment viewed from lab microscope images. The fusion heat of HVPM indicates the embedment of microcapsules, which results in a thermal energy storage capability. The practical effect in controlling inner-column temperature is to be shown in the next section. Figure 5: FTIR spectra for polymeric adsorbent before and after post-crosslinking reaction. Figure 6: Comparison of the differential scanning calorimetric (DSC) thermograms for wax, DVB-wax microcapsules, and HVPM. The N\({}_{2}\) adsorption-desorption isotherms of HVPM at 77 K are demonstrated in Figure 7. It is observed that at lower relative pressure (P/P\({}_{0}\) < 0.05), the amount of adsorbed nitrogen increases sharply as the relative pressure increases. At high relative pressure, however, no further significant increase was found. According to the International Union of Pure and Applied Chemistry (IUPAC) classification, this kind of isotherm can be classified as type I, proving the existence of micropore-dominant structure. Relative physical properties are listed in Table 2.  
As shown in Table 2, it is clear that the hypercrosslinked adsorbent has a relatively large specific surface area (665 m\({}^{2}\)/g) and a micropore-dominant structure (micropore volume 0.24 cm\({}^{3}\)/g, total pore volume 0.38 cm\({}^{3}\)/g), which was beneficial for the adsorption process.