## 7 Polymerization Time and Condensation Time  
CVD (chemical vapor deposition) polymerization techniques not only demonstrate advantages in polymer thin film applications, but also for the synthesis of polymer particles. Gas-phase deposition helps circumvent the limitations of conventional solution-based PNPs (polymer nanoparticle) synthesis procedures. This is evident not only in terms of solvent-free conditions but also significantly reduces the required polymerization time. [PERSON] that the entire polymerization process of synthesizing nanodome particles through CVD can be completed in a matter of seconds. Moreover, in the experiment, after the condensation of monomer droplets, free radicals initiate the polymerization and solidification of nanodomes in less than 45 s.  
This polymerization process is much faster than the time required for CVD technology to synthesize films, and [PERSON] is also highly confident in this aspect. He took twice the amount of time compared to [PERSON] to ensure the complete polymerization of monomer droplets, and it only took 2 min. Therefore, a key step in the two-step synthesis of nanodomes, droplet-like, and cap-shaped polymer particles is the condensation phase. During this phase, the monomers need sufficient time for nucleation to occur in liquid droplets with a critical radius, and the growth of these liquid droplets also requires time, including enough diffusion time for eventual coalescence, as shown in Figure 8[41]. Considering the arrival of a single activated radical initiator into a condensed liquid monomer film, then about 1 s is required for the chain to grow to 104 g/mol. In dropwise  
Figure 7: Nucleation of water droplets on hydrophobic surfaces and minimum critical radius [39]. condensation, the process is cyclical, starting with the formation of liquid droplets at the atomic-scale selective nucleation sites. These droplets grow through stages of direct condensation, coalescence, and departure. This ensures a continuous cycle of condensation events. In the context of the CDP synthesis technique, the first phase involves the deposition of monomers on a solid surface, forming spherical liquid droplets. This process closely resembles the cyclical nature of dropwise condensation. Looking at the entire process, the condensation phase takes significantly more time compared to the second phase of the CDP synthesis, where monomers undergo polymerization initiated by radicals. Therefore, we can accurately say that the time scale for polymerization is a few orders of magnitude smaller than that of condensation. Size Reduction in Nanodomes in Two-Step Synthesis Due to Unreacted Initiator and Monomer Evaporation during Exhaust Process  
The kinetic analysis indicates that the deposition process is constrained by adsorption, likely due to the limitation in the surface concentration of monomers. This result supports the hypothesis that polymerization takes place on the substrate rather than the growth of polymer chains in the gas phase, followed by deposition. This finding makes the described synthetic approach highly suitable for coating uneven substrates or substrates with high dimensional complexity. Therefore, in the two-step approach, initiating the deposition and condensation of monomers in the gas phase to form liquid nanodomes, followed by introducing initiator-laden nanodomes for a solid-phase polymerization reaction, is highly insightful. The practice is inspiring. In determining the final dimensions of PNDs, apart from the crucial condensation phase, the evaporation step for removing the unreacted initiator and monomer from the chamber also plays a pivotal role. The Figure 9 portrays the condensation and polymerization of nanodomes, succeeded by an evaporation-based degassing phase. Our recent findings suggest that as the monomers and initiators are extracted, the nanodomes undergo a conspicuous volume contraction.