# Tuning of Morphology and Surface Properties of Porous Silicones by Chemical Modification
## 3 Results and Discussion
The FT-IR spectra are shown in Figure 1, in both cases compared with DH100 as a reference. The presence of aliphatic CH\({}_{2}\) groups in DHH is proved by the adsorption bands at 2928 cm\({}^{-1}\) (asymmetric stretching vibration) and 2858 cm\({}^{-1}\) (symmetric stretching vibration) (Figure 1a). In DHS, the CH\({}_{2}\) asymmetric stretching can be seen at 2920 cm\({}^{-1}\), while the band at 2960 (CH\({}_{3}\) asymmetric stretching vibration) is more pronounced than in DH100. In addition, two bands at 862 and 837 cm\({}^{-1}\) are assignable to Si-C stretching vibrations, one of them being due to trimethylsilyl groups [30]. The absence of a double bond absorption band, which would have appeared at around 3050 cm\({}^{-1}\), implies that the conversion of hexene and allyltrimethylsilane was high and that the unreacted reagent was removed in the purification step. Like in the other cases, reminiscent Si-H bands still exist in both chemically modified samples. Taking PMHS as a reference, the conversion of the Si-H groups is higher than in DH100. However, two concurrent reactions occur, and part of the reacted Si-H groups is involved in cross-linking. Assuming the same conversion of Si-H groups in the cross-linking reaction, calculations indicate 28.5% modification with n-hexene (theoretical 28%) and 24% modification with ATMS (vs. 26% theoretical). Thus, we can conclude that the hexyl and propylene-trimethylsilyl groups are chemically attached to the polysiloxane backbone, and the modification reactions occurred in high yield. An alternative set of samples was obtained by UV-photoinitiated thiol-ene addition (Scheme 1B), using a poly(dimethyl-methylvinyl)siloxane copolymer with \(\sim\)50% vinyl groups, trimethyllop propane tris(3-mercaptoethanolpropionate) (SHCL) as a cross-linking agent, and 2,2-dimethoxy-2-phenylacetophenone (DMPA) as a photoinitiator (UV50). Modification of this copolymer by the addition of mercaptoethanol, occurring simultaneously with the cross-linking process, was designed to provide hydrophilicity in the resultant porous silicone (UVME). The FT-IR spectrum of UV50 showed incomplete conversion of the vinyl groups, since absorption bands at 3057 cm\({}^{-1}\) (CH stretching) and 532 cm\({}^{-1}\) (twisting vibrations) were still present. The chemical modification with mercaptoethanol resulted in the nearly complete disappearance of these bands, along with an increase in the CH\({}_{2}\) band at 2920 cm\({}^{-1}\) and in the OH band and the presence of thioether bands at 700 and 673 cm \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Code** & **CLD, theor. \%** & **Conversion, \%** & **CLD (FT-IR), \%** & **(CH\({}_{3}\))\({}_{2}\)SiO, mole \%** & **CA, \({}^{\circ}\)** \\ \hline DH100 & 100 & 77 \({}^{\text{a}}\) & 77 & 0 & 113.5 \(\pm\) 3 \\ \hline DH70 & 70 & & & 30 & 151 \(\pm\) 1 \\ \hline DH44 & 44 & & & 56 & 162 \(\pm\) 3 (lotus) \\ \hline DH30 & 30 & 39 \({}^{\text{a}}\) & 11.7 & 70 & 131.5 \(\pm\) 2 (petal, CAH 60\({}^{\circ}\)) \({}^{\text{d}}\) \\ \hline DHH & 72 \({}^{\text{b}}\) & 84 \({}^{\text{a}}\) & 55 & 0 & 124.5 \(\pm\) 2 \\ \hline DHS & 74 \({}^{\text{b}}\) & 81 \({}^{\text{a}}\) & 57 & 0 & 130 \(\pm\) 3 (petal, CAH 51\({}^{\circ}\)) \({}^{\text{d}}\) \\ \hline UV50 & 50 & 84 \({}^{\text{c}}\) & 42 & 50 & 129 \(\pm\) 2 (petal, CAH 45\({}^{\circ}\)) \({}^{\text{d}}\) \\ \hline UVME & 39 & 98 \({}^{\text{c}}\) & 49 & 50 & 87 \(\pm\) 1 \\ \hline \hline \end{tabular}  
* \({}^{\text{a}}\) Calculated from FT-IR, as [(A\({}_{2170}/A_{1260}\))]final/[(A\({}_{2170}/A_{120}\))]IOHHS] \(\times\) 100. \({}^{\text{b}}\) Representing the theoretical unmodified Si-H groups. \({}^{\text{c}}\) Calculated from FT-IR, as [(A\({}_{3057}/A_{1260}\))]final/[(A\({}_{3057}/A_{1260}\))V50] \(\times\) 100. \({}^{\text{d}}\) Difference between CAs on the two sides of the drop at 90\({}^{\circ}\) tilt angle.  
\end{table} 
Table 2: Cross-linking degrees, conversion (from FT-IR), composition details, and contact angles (CAs) of the porous materials.