# Emulsion Polymerization of Tung Oil-Based Latexes with Asolectin as a Biorenewable Surfactant
## 3 Results and Discussion
The absence of a significant peak in the same region of the spectrum of the post-cured sample (Figure 8D) suggests that the carbon-carbon double bonds in the monomers were completely reacted during the polymerization and post-cure processes. The additional peak observed in the spectrum of BMA at approximately 1725 cm\({}^{-1}\) can be attributed to the carbonyl group. Since fully polymerized samples were obtained from the emulsion containing 40 wt.% tung oil after a post cure step of 2 h at 140 \({}^{\circ}\)C, the post cure step was applied to all monomer compositions. After the post cure step, emulsions containing 40-80 wt.% of tung oil were analyzed by DSC (Figure 9) and TGA (Figure 10). The similarity among the DSC curves from samples containing 40-80 wt.% of tung oil (Figure 9) suggests that a fully cured system can be obtained from any of these compositions after a 2 h post cure step at 140 \({}^{\circ}\)C. Indeed, no obvious exothermic peaks can be observed at approximately 160 \({}^{\circ}\)C after the post-cure (Figure 9). It can also be seen that the change in the baseline at approximately 70 \({}^{\circ}\)C, possibly indicating a glass transition temperature, is present in all curves in Figure 9. TGA results (Figure 10) also illustrate similar thermal properties between post-cured samples prepared with 200 mg of total monomer weight and with 40-80 wt.% of tung oil. Very little variability with no clear trend can be observed among the samples when heated to 600 \({}^{\circ}\)C under air. Figure 8: Raman spectra of (**A**) asolectin, (**B**) BMA, (**C**) tung oil, and (**D**) dried emulsion containing 200 mg of total monomer weight with 40 wt.% of tung oil post-cured at 140 \({}^{\circ}\)C for 2 h.  
Transmission microscopy was performed on a cured emulsion (Figure 11), revealing the morphology of the system upon cure. A darker outer layer of the structures seen and a lighter core (more clearly seen in Figure 11A) suggests the formation of hollow spheres, giving the latexes described in this manuscript a range of potential applications besides coatings, including nano-catalyst encapsulation and drug delivery agents. Indeed, upon emulsification in the presence of asolectin, droplets of non-polar monomers are formed. The crosslinking of the droplets' contents during polymerization ensures that the droplet morphology is maintained even after solvent removal, as confirmed by STEM (Figure 11). Due to the low monomer concentration in the emulsions originally prepared, it is assumed that most of the original volume of a droplet consists of xylene, which is removed upon drying, leaving a hollow sphere referred to as a \"vesicle\". Despite a few larger particles seen in Figure 11A, the majority of the particles exhibit diameters on the order of 100 nm (Figure 11B,C). In order to more accurately determine the vesicles' particle size, cured emulsions were characterized using a zetasizer. Table 2 displays average diameter and polydispersity data for samples containing 200 mg of total monomer weight and 40-80 wt.% of tung oil. Figure 10: Thermogravimetric Analysis (TGA) curves of dried latexes containing 200 mg of total monomer weight with (**A**) 80 wt.% of tung oil, (**B**) 70 wt.% of tung oil, (**C**) 55 wt.% of tung oil, and (**D**) 40 wt.% of tung oil. All samples were subjected to an initial cure step at 100 \({}^{\circ}\)C for 24 h, followed by a drying process in a vacuum oven at 60 \({}^{\circ}\)C for 24 h, and a post cure step at 140 \({}^{\circ}\)C for 2 h.  
Figure 9: DSC curves of dried latexes containing 200 mg of total monomer weight with (**A**) 80 wt.% of tung oil, (**B**) 70 wt.% of tung oil, (**C**) 55 wt.% of tung oil, and (**D**) 40 wt.% of tung oil. All samples were subjected to an initial cure step at 100 \({}^{\circ}\)C for 24 h, followed by a drying process in a vacuum oven at 60 \({}^{\circ}\)C for 24 h, and a post cure step at 140 \({}^{\circ}\)C for 2 h.  
From the data in Table 2, a clear trend of increasing particle size can be observed for increasing tung oil content.