## 3 Results and Discussion
The activation energy of the crosslinking reaction for the HNP, PS, and PDMS with BMI was 36.91, 45.31, and 41.34 kJ mol\({}^{-1}\), respectively, and they are listed in Figure 3:6 The values are similar to those found in previous studies for the DA reaction in polymeric systems [36; 39; 40]. Compared to the three crosslinking reactions of HNP, PS, and PDMS, the _Ea_ of the Diels-Alder reaction of HNP with BMI is smaller thanfuran functionalized homopolymers. This result may be because of the HNP-F's spherical particle shape, which may be an approach to control assembly and disassembly processes. Furthermore, the chain flexibility of PDMS-F resulted in a lower \(E_{a}\) compared to the more rigid one of the PS-F chain in the crosslinking reaction of homopolymers. Differential scanning calorimetry (DSC) was used to study the retro Diels-Alder reaction of the crosslinked polymers with BMI. Figure 9a-c shows the heating curves of the DSC analysis of HNP-F, PS-F, and PDMS-F after reaction with the BMI. As seen in the thermogram, a broad peak at 154 \({}^{\circ}\)C is observed, indicating the cleavage of HNP-BMI via a retro-DA (rDA) reaction in the first heating curve. No peak is observed in the second heating curve since the cooling process time was not long enough to form the DA adduct [37]. \begin{table}
\begin{tabular}{l c} \hline \hline
**Furan Functionalized End-Group Samples** &
\begin{tabular}{c} **The Activation Energy of the Crosslinking** \\ **Reaction with BMI** \\ \end{tabular} \\ \hline HNP-F & 46.57 kJ mol\({}^{-1}\) \\ PS-F & 67.61 kJ mol\({}^{-1}\) \\ PDMS-F & 54.22 kJ mol\({}^{-1}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Activation energy for the Diels–Alder reactions of the furan functionalized polymers with BMI. \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Polymer** & **Kinetic Order** & **T/\({}^{\circ}\)C** & **50** & **60** & **70** \\ \hline HNP-F & n = 1 & k1/min\({}^{-1}\) & 0.0011 & 0.0007 & 0.0004 \\  & n = 2 & k2/(min\({}^{-1}\) mol\({}^{-1}\) L) & 0.0011 & 0.0007 & 0.0004 \\ PS-F & n = 1 & k1/min\({}^{-1}\) & 0.0012 & 0.0006 & 0.0003 \\  & n = 2 & k2/(min\({}^{-1}  
Scanning electron microscopy was used to investigate the morphology of the HNP-F, PS-F, and PDMS-F before and after the crosslinking reaction with BMI. All samples were prepared by drop-casting on silicon wafers using chloroform as the solvent. The crosslinked polymers showed different morphologies. Crosslinked HNP-F TPEs showed the most uniform surface with some anisotropic pores (Figure 10b), which is expected because the available polymer did not totally cover the silicon wafer surface. The SEM image (Figure 10c), decrosslinked after heating the silicon wafer to 150 \({}^{\circ}\)C, does not have surface smoothness. The difference between the two uncrosslinked SEM images (Figure 10a,c) can be attributed to the preparation of the two samples, i.e., one was drop-cast (Figure 10a), and the second one (Figure 10c) was heated first to 50 \({}^{\circ}\)C and then to 150 \({}^{\circ}\)C to decrosslink it. Furthermore, AFM images of crosslinked HNP-F also reveal smooth porous surfaces (Figure 10d,e). Figure 9: (**a**) Heating curve of DSC analysis of crosslinked HNP-F with BMI; (**b**) heating curve of the DSC analysis of PS-F with BMI. The retro-DA peak, which indicates the cleavage of PS-BMI, is observed at 143 \({}^{\circ}\)C. (**c**) PDMS shows cleavage of PDMS-BMI at around 150 \({}^{\circ}\)C.