## 3 Results and Discussion
### Synthesis of SNP-b-P (NB-PSt) SMNCs  
Subsequently, we carried out the regioselective deposition of silica under mild conditions. The PCNB\({}_{87}\)-b-P (NB-PSt\({}_{80}\))\({}_{19}\) BBPs were dissolved in tetrahydrofuran (THF), a good solvent for the PSt component, to prepare a 1 mg/mL solution. Aqueous ammonia (25%) was then slowly added to the BBP solution until the volume content reached 4 vol%. At this point, the volume content of water was approximately 3 vol%. It is important to note that both water and methanol, the byproduct of silane hydrolysis, are poor solvents for PSt sidechains. A high volume content of poor solvents (water and methanol) can induce phase separation and even severe aggregation of the BBPs. The critical volume fraction of water for the collapse of PSt chains in a THF/water mixed solvent is typically 5-8 vol% [47]. However, only the monodisperse state of BBPs facilitates high-quality silica deposition. Therefore, in contrast to the conventional Stober method, we had to deposit silica NPs under relatively mild conditions. Tetramethyl orthosilicate (TMOS), which exhibits a higher reactivity than ethyl orthosilicate, was selected as the model precursor for this condition. Upon the addition of NH\({}_{3}\)-H\({}_{2}\)O, the ionization of carboxyl groups from PCNB led to chain collapse due to reduced solubility in THF. The \(a/n>1\) boundary condition ensured that ionized PCNB chains partially protruded from the crowdy sidechains, forming nucleating sites. These nucleating agents attracted silica oligomers generated during the hydrolysis and polycondensation of TMOS and promoted their further condensation into silica nanoparticles. Each reaction was conducted for 24 h at 40 \({}^{\circ}\)C to ensure the complete consumption of TMOS.  
The feeding molar ratio of TMOS to the carboxyl groups from BBPs, defined as \(\text{n}_{\text{TMOS:}}\text{n}_{\text{COOH}}\), determines the final size of silica lobes. Figure 3 clearly shows the structure of SMNCs synthesized using PCNB\({}_{87}\)-b-P (NB-PSt\({}_{80}\))\({}_{19}\) BBPs at a molar ratio of \(\text{n}_{\text{TMOS:}}\text{n}_{\text{COOH}}\) = 10:1. The size of the SMNCs was ~14.0 \(\pm\) 3.0 nm (Figure 3c, orange column), with a silica NP lobe of ~5 nm, as shown in the magnified SEM (Figure 3a inset) and TEM images (Figure 3b). The BBP backbones of SMNCs exhibit various topologies--for example, the globular (#1) and rod-like (#2) structures in Figure 3a's inset. It is likely that the flexible conformation of BBP tails leads to uneven spherical shapes during the drying process for SEM/TEM sample preparation. TGA was performed on the synthesized SMNCs to determine the mass ratio between the silica lobes and the polymer tails. As shown in Figure S5, the bottlebrush polymer exhibited weight loss initiating at 350 \({}^{\circ}\)C, with complete decomposition achieved by 450 \({}^{\circ}\)C. In contrast, the SMNCs retained 22.2% of their mass at 800 \({}^{\circ}\)C, yielding a silica-to-polymer mass ratio of 1:2.69, which is close to the theoretical value (1:2.33). Combined with TEM verification of the single-lobe morphology of the SMNCs, these results confirm the one-to-one correspondence between the silica nanoparticles and the bottlebrush polymer tails.  
Figure 2: The \({}^{1}\)H NMR spectra of tBNB (**a**), PtBNB (**b**), MM NB-PSt (**c**), PtBNB-b-P (NB-PSt) (**d**), and PCNB-b-P (NB-PSt) (**e**) were recorded in CDCl\({}_{3}\), respectively. The insets in (**b–e**) magnify the signals ranging from 4.8 to 6.0 ppm, which are highlighted by red boxes.