Mcl Synthesis Lab Report

Molecular weight (MW) of PCL synthesized was calculated theoretically (Appendix I) based on the ratio between initiator and monomer present. Amount of yield was calculated thereafter upon synthesization and precipitation process in methanol solution. Methanol and Toluene were used for precipitation as the solvents were not good solvents for PCL. Instead, the polar nature of Methanol is used to dissolve the presence of other components formed during reaction such as phenols. Phenols were suspected of its toxicity and can cause potential harm to human body. Thus, it would be better to eliminate as much phenols as possible.
20 g of e-caprolactone was drawn and used as a starting monomer for the polymerisation. Hence ideally the amount of yield should be equivalent. As seen in Table 6, precipitation was performed twice for PCL 3000. Yield obtained after the first precipitation was 23.10 g. It was believed that there were an excess of phenols that were trapped in PCL powder

The % crystallinity calculated for the samples have reflected differently from the 1st cycle. The % crystallinity for the PCL samples decreased with increasing molecular weight. The difference in results can also be seen in Figure 29 and 30. The peaks obtained in Figure 29 were much broader as compared to Figure 30. Furthermore, there were additional shoulder peak along the main peak. This has been reported in the literature.
Amount of reagents that were used for synthesizing both PCL and PCLF samples were calculated based on theoretical calculations in order to obtain that certain MW of the polymer (Appendix I and II). In this experiment, GPC was used to obtain the exact molecular weight of the polymer. As seen in Table 8, the expected MW for PCL 3000 and PCL 9000 were 3000 g/mol and 9000 g/mol respectively. However, the GPC results obtained for PCL 3000 and 9000 were 6800 g/mol and 15000 g/mol