## 2 Results and Discussion
### Application Testing of Controlled Morphology Hyperbranched Polymers
#### 2.2.2 Film Formation
Currently, the range of the errors suggests that this can  
Figure 6: Interferometry images for an experiment utilising a 1 wt% semi-block-like HB polymer in an oil solution where image (**A**) is the zero-point image (i.e. prior to analysis) and images (**B–G**) depict different time points in the analysis. only be regarded as an indicative trend, but clearly shows differentiated performance from the base oil alone. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Step No**} & **Maximum** & **Minimum** & **Mean Thickness** & **Standard** & **Measurement** \\  & Thickness [nm] & **Thickness [nm]** & **[nm]** & **Deviation [nm]** & **Temperature [\({}^{\circ}\)C]** \\ \hline A (Zero Point) & 4.0 & \(-\)10.0 & 0.2 & 1.3 & 60 \\ B (**Step 3**) & 217.0 & 0.0 & 179.9 & 67.9 & 60 \\ C (**Step 5**) & 231.0 & 0.0 & 184.3 & 63.0 & 60 \\ D (**Step 7**) & 241.0 & 7.0 & 196.3 & 53.6 & 90 \\ E (**Step 9**) & 230.0 & 0.0 & 200.3 & 35.4 & 90 \\ F (**Step 11**) & 216.0 & 127.0 & 202.3 & 3.4 & 120 \\ G (**Step13**) & 219.0 & 74.0 & 202.3 & 4.2 & 120 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the film thickness data obtained from interferometry for a 1 wt% semi-block-like HB polymer/base oil formulation. The blue shading indicates that the measurement was conducted after film buildup (i.e., following a period of constant temperature and rolling speed). The orange shading indicates that the measurement was conducted after a Stribeck Curve measurement was conducted. The plot (right) is a visual representation of this data (B–G). Figure 7: Plots of the film thickness (nm) for a 1 wt% semi-block-like HB polymer and base oil formulation. (**A–G**) **Top**: two-dimensional scatter plots for each step, where the data has been binned, as indicated in the legend. (**A\({}^{\prime}\)**–G\({}^{\prime}\)) **Bottom**: three-dimensional surface plots for each step. The labels (**A–G**) correlate across the two plots and with the labels in Figure 6.  
Finally, the interferometry data for a 1 wt% solution in oil of the block-like HB polymer were collected and analysed using the methods described above. This data is shown in Figures S3-S5 in the ESI document. The interferometry images in Figure S5 again show a lack of elongation, indicating that there is very little wear occurring between the surfaces. This also showed the significant formation of a surface film, as indicated by the darkening of the contact point. The visualisation data for the film are contained in Figure S6, along with additional interpretation comments. Thus, it was concluded that, in a similar manner to the semi-block-like polymer, a significant film forms rapidly, with the majority of the measured film having a thickness of \(>\)200 nm in plot 9B. From this step, the film thickness can be seen to continue to grow minimally and become more uniform as the test progresses, with very little variation in film thickness seen after plot 9D. This suggests that the block-like HB polymer forms a more robust film more rapidly than the semi-block-like copolymer. Furthermore, the film stabilises earlier in the test and is not affected as greatly by changes in temperature and rotation regime. The block-like polymer data summary is shown in Table 5 and visualised in Figure S7. The average thin film formed for the block-like HB solution was initially thicker than that of the semi-block-like polymer, with an initial film thickness at step 3 (entry B) of 195 nm, compared to 180 nm, respectively. Similar to the semi-block-like case, it was not degraded with increasing temperature and time, and grew as the experiment occurred, forming a maximum film thickness of 204 nm at step 11 (F). This is very similar to the 202 nm maximum average thickness observed for the semi-block-like HB, although the overall difference in thickness of 9 nm is not significant compared to the associated errors.