# 2-Methoxy-4-Vinylphenol as a Biobased Monomer Precursor for Thermoplastics and Thermoset Polymers
## 3 Results
### Thermosetting Applications
The thermomechanical properties of the resulting films were investigated using DMA, and the storage modulus (E\({}^{\prime}\)) and tan8 were plotted against temperature (Figure 2). As shown in Figure 2a, the DMA thermograms indicated a typical thermoset behavior characterized by a glassy plateau and a rubbery plateau below and above the glass transition, respectively. Initially, the samples were equilibrated at \(-\)50 \({}^{\circ}\)C, below \(T_{g}\). In that glassy region, the storage modulus ranged between 1.4 and 2.4 GPa (Table 2). The storage modulus values are similar to those of other thermosets containing small amounts of DVB used as the crosslink [50], as well as sobrerol diacrylate thermosets prepared via thiol-ene chemistry [51]. However, these values did not indicate a clear trend that could be related to the aliphatic chain length or the crosslinking density (v\({}_{\text{e}}\)). By increasing the temperature, a sharp transition was observed, attributed to the glass transition region. The \(T_{\text{g}}^{\text{tan}\otimes}\) was also evaluated from the peak of tan8 (Figure 2b, Table 2), which was found to be higher than that obtained from DSC for all samples, as also reported elsewhere [48; 52]. However, X(1,6-MVP-3T) and X(1,6-MVP-4T) exhibited the highest \(T_{\text{g}}^{\text{tan}\otimes}\), deviating from the trend previously observed by DSC. This may have been due to homopolymerization of the DVB-like monomers during the initial melting step in the oven, as described previously from the DSC results (Figure S37) [51]. The degree of homopolymerization was indirectly determined through the gel content (Table 2). Only thermosets X(1,10-MVP-3T), X(1,10-MVP-4T), and X(1,3-MVP-3T) exhibited a high gel content, i.e., \(>\)90%. Although this could have been avoided by preparing larger mixing batches in the presence of solvent [53], as described previously, in this work, we aimed for solvent-free procedures, thus reducing undesired chemical waste. For the case of 3T crosslinked samples, the thermosets broke at the grips of the DMA instrument after reaching 80 \({}^{\circ}\)C. In addition, these samples exhibited lower storage moduli compared to their 4T counterparts. Moreover, the v\({}_{\text{e}}\) estimated at 80 \({}^{\circ}\)C according to Equation (S4) was calculated to be three times higher for 4T compared to 3T, which was expected as more -SH units were available for crosslinking in the case of 4T compared to 3T, thus increasing the v\({}_{\text{e}}\). This was qualitatively observed by the rightward shift of the storage moduli in the glass transition region [52]. To evaluate the robustness of the thermosets, a simplified stability test was conducted, where the films were immersed in a vial containing different aqueous and organic solvents for 7 days (Figure S39). Although it was found that CHCl\({}_{3}\) disintegrated all thermosets (not dissolved), as shown for other crosslinked networks containing eugenol and DVB, the samples exhibited better chemical stability toward DMSO compared to the thermosets with DVB and eugenol [55]. However, X(1,10-MVP-4T) was found to disintegrate when immersed in NaOH (1 M) and DMSO. Some discoloration was observed for all samples immersed in NaOH except for X(1,3-MVP-3T) and X(1,3-MVP-4T). The polarity of the thermosets was investigated through contact-angle measurements (CA) against water (Table S10). This approach provided a better understanding of the hydrophobicity of the thermosets. All films possessed a hydrophobic character with CAs close to 78\({}^{\circ}\). In summary, the facile modification route of MVP resulted in DVB-like difunctional monomers with potential use in thermally crosslinked thiol-ene networks. However, electron-poor alkenes are also susceptible to self-initiation. We believe that self-initiation resulted in a less-defined network, which could explain the lack of clear DMA trends and gel content variations.