# Textured and Hierarchically Constructed Polymer Micro- and Nanoparticles
## 3 Results
### Textured Nanoparticles of Polymethylmethacrylate and Polydivinylbenzene
The dispersity (relative standard deviation) of the diameter was 11-16% and 15-25% of the substructures. As a second monomer, DVB was studied analogous to [11]. Unlike the monofunctional MMA monomer, DVB bears two double bonds and needs no extra crosslinking agent to form a 3D network. On the other hand, its rate of chain propagation is much slower, allowing the progress of the reaction to remain controllable. The following protocol for the DVB monomer was applied:  
* The monomer phase consisted of DVB and toluene in varying quantities, and AIBN in a concentration of 60-120 mM. * The carrier phase consisted of water with varying types and quantities of additives (surfactants and polyelectrolytes). * Using the microfluidic hole-plate device, an emulsion was produced at flow rates of 150-200 mL/min (monomer) and 1500 mL/min (carrier) and piped into the thermostat held at 85 \({}^{\circ}\)C.
* After 90 min, the reaction mixture was removed from the thermostat and treated similar to MMA. Figure 3 depicts the effect of additives to the aqueous carrier phase on the shape of the particles. In the presence of nonionic surfactants in higher concentration, textured particles formed. With low-dosage anionic surfactant SDS as well as with cat- or anionic polyelectrolytes PDADMAC and PSS, the resulting particles were almost spherical. In the case of PSS, the surface was nearly smooth within the image resolution; with SDS, a slightly grained texture occurred, and with PDADMAC, the surface showed faint blisters. Thus, Span20 was chosen for the following experiments to study the effect of toluene solvent on the particle structure. Figure 4 shows SEM images of particles produced with different volume fractions of monomer and solvent. Table 2 lists the structural parameters of Figures 3a,b and 4. The large particles in Figure 4a formed a super structure of about 490 nm diameter, which at a closer sight was composed of smaller particles, which were of comparable size to those from the other variants of 100-200 nm. Again, these smaller particles all had substructures 10-30 nm in size. The dispersity of the diameter in most cases was 12-17% and 15-30% of the substructures. Eventually, no strong solvent effect was detectable. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Figure** & **EGDMA** & **DVB** & **Incubation Time** & **Particle Size** & **Substructure** \\  & **ppm** & **\%** & **min** & **nm** & **nm** \\ \hline Figure 1a & 680 & 6.8 & 1 & 147 & 21 \\ Figures 1b and 2c & 680 & 6.8 & 2 & 426 & 73 \\ Figure 1c & 680 & 6.8 & 3 & 95 & n.a. \\ Figure 1d & 680 & 6.8 & 5 & 496 & 86  
Figure 3: SEM images of poly-DVB particles synthesized in the presence of additives in the carrier phase: (**a**) 81.5 mM Brij52, (**b**) 86.6 mM Span20, (**c**) 1.5 mM SDS, (**d**) 1.0 mM PSS, and (**e**) 0.5 mM (per monomer unit) PDADMAC. Monomer phase: 33% DVB, 67% toluene, and 66 mM AIBN. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Figure** & **Surfactant** & \begin{tabular}{c} **Toluene** \\ **Volume Fraction** \\ \end{tabular} & \
\begin{tabular}{c} **Particle Size** \\ **nm** \\ \end{tabular} &
\begin{tabular}{c} **Substructure** \\ **nm** \\ \end{tabular} \\ \hline Figure 3a & Brij52, 81.5 mM & 67\% & 214 & 14 \\ Figure 3b & Span20, 86.6 mM & 67\% & 172 & 20 \\ \hline Figure 4a & Span 20, 173.3 mM & 67\% & 121 & 26 \\ Figure 4b & Span 20, 173.3 mM & 50\% & 182 & 18 \\ Figure 4c & Span 20, 173.3 mM & 33\% & 185 & 26 \\ Figure 4d & Span 20, 173.3 mM & 25\% & 100 & 11 \\ Figure 4e & Span 20, 173.3 mM & 0\% & 164 & 19 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Mean particle sizes and sizes of substructures on the particle surface derived from Figures 3 and 4.