## 3 Results and Discussion
### Physicochemical Properties of HMS-SO\({}_{3}\)H and NRHMS-SO\({}_{3}\)H
Both HMS-SO\({}_{3}\)H and NRHMS-SO\({}_{3}\)H series provided similar N\({}_{2}\) physisorption isotherms of type IV (Figures 6A and 7A), representing a hexagonally mesostructured framework, as also confirmed via low-angle XRD patterns (Figures 6B and 7B). A large hysteresis loop at P/P\({}_{0}\) of 0.8-1.0 corresponded to the interparticle voids from the agglomeration of particles. A continuous reduction in the hysteresis loop was seen for the increased MPTMS loading from 0.2 to 0.4, suggesting increased chemically bonded MPTMs on the silica framework via the co-condensation method. As a result, the mesophase assembly was disturbed, shortening the long-range ordered structure formation [39]. Nevertheless, the TEM images of HMS-SO\({}_{3}\)H (0.4) and NRHMS-SO\({}_{3}\)H (0.4) showed the retention of a wormhole-like motif structure. S\({}_{\text{BET}}\), V\({}_{\text{P}}\), and V\({}_{\text{T}}\) decreased with an increased MPTMS loading level, indicating successful functionalization on the material surface (Table 2) [40]. At the MPTMS/TEOS ratio of 0.6, the disappearance of the (100) reflection peak indicated the collapse of the mesoporous structure. It should be noted that the NRHMS-SO\({}_{3}\)H series provided decreased S\({}_{\text{BET}}\), V\({}_{\text{P}}\), and V\({}_{\text{T}}\) but with a thicker mesoporous wall, indicating that the rubber phase was successfully infiltrated between the mesostructured silica frameworks [41]. Surprisingly, NRHMS-SO\({}_{3}\)H (0.4) exhibited a relatively small reduction in the textural properties, compared with HMS-SO\({}_{3}\)H (0.4). For example, S\({}_{\text{BET}}\) of the NRHMS-SO\({}_{3}\)H series slightly decreased from 594 m\({}^{2}\) g\({}^{-1}\) to 400 m\({}^{2}\) g\({}^{-1}\) when increasing the MPTMS/TEOS ratio from 0.2 to 0.4, while HMS-SO\({}_{3}\)H (0.4) exhibited a 36% reduction of S\({}_{\text{BET}}\) from HMS-SO\({}_{3}\)H (0.2). It was predicted that the presence of NR reduced the polarity of  
Figure 5: Representative TG and DTA curves of (**A**) HMS-SO\({}_{3}\)H and (**B**) NRHMS-SO\({}_{3}\)H materials with different MPTMS loading levels. the material surface by covering a part of silanol groups, further preventing the aggregation of MPTMS that functionalized at the pore entrance of mesoporous nanocomposites. Figure 6: Representative (**A**) N\({}_{2}\) physisorption isotherms and (**B**) low-angle XRD patterns of HMS-SO\({}_{3}\)H with different loading levels. (**C**) TEM images of HMS-SO\({}_{3}\)H (0.4) at a magnification of 300,000\(\times\). Figure 7: Representative (**A**) N\({}_{2}\) physisorption isotherms and (**B**) low-angle XRD patterns of NRHMS-SO\({}_{3}\)H with different loading levels. (**C**) TEM images of NRHMS-SO\({}_{3}\)H (0.4) at a magnification of 300,000\(\times\). The hydrophobicity of HMS-SO\({}_{3}\)H and NRHMS-SO\({}_{3}\)H materials was evaluated by H\({}_{2}\)O adsorption-desorption measurement (Table 2). Both material series exhibited an increased V\({}_{\text{m, H2O}}\) with the increasing MPTMS due to the hydrophilic sulfonic acid groups that enhanced the water affinity of the material surface. The NRHMS-SO\({}_{3}\)H series provided lower water adsorption than the HMS-SO\({}_{3}\)H counterparts due to the dispersed rubber phase, creating a hydrophobic environment on the surface of nanocomposites. According to a previous study, the hydrophobicity of the material surface exhibited superior catalytic activity in the esterification reaction by preventing water absorption on the acid sites [42]. However, increased hydrophobicity affected the adsorption rate of reactants and created a trade-off effect between the hydrophobic character and physicochemical properties, such as losing acidic properties to gain hydrophobicity [43], which can be optimized by varying the loading level of organo-functional groups on the catalyst surface. The total acidity of the HMS-SO\({}_{3}\)H and NRHMS-SO\({}_{3}\)H series was mainly evaluated via acid-base titration (Table 1).