# Synthesis of Shape-Memory Polyurethanes: Combined Experimental and Simulation Studies
## 3 Results and Discussion
### Thermal Analyses
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **T\({}_{\rm c}\)** & **\(\Delta\)H\({}_{\rm c}\)** & **T\({}_{\rm m}\)** & **\(\Delta\)H\({}_{\rm m}\)** \\ \cline{2-5}  & \({}^{\circ}\)C & **J**\(\times\) g\({}^{-1}\) & \({}^{\circ}\)C & **J**\(\times\) g\({}^{-1}\) \\ \hline E\_PCUU3000\_3.5 & \(-12\pm 1\) & \(13\pm 1\) & \(32\pm 1\) & \(12\pm 1\) \\ E\_PCUU3000\_3 & \(-7\pm 1\) & \(19\pm 1\) & \(38\pm 1\) & \(18\pm 1\) \\ E\_PCUU3000\_2.5 & \(-9\pm 1\) & \(16\pm 1\) & \(41\pm 1\) & \(21\pm 1\) \\ E\_PCUU3000\_2 & \(-6\pm 1\) & \(20\pm 1\) & \(43\pm 1\) & \(22\pm 1\) \\ E\_PCUU3000\_1.5 & \(0\pm 1\) & \(24\pm 1\) & \(47\pm 1\) & \(25\pm 1\) \\ E\_PCUU5000\_3 & \(11\pm 1\) & \(30\pm 1\) & \(50\pm 1\) & \(30\pm 1\) \\ E\_PCUU5000\_2 & \(19\pm 1\) & \(35\pm 1\) & \(53\pm 1\) & \(62\pm 1\) \\ E\_OCD_3000 & \(40\pm 1\) & \(77\pm 1\) & \(57\pm 1\) & \(76\pm 1\) \\ E\_OCD_5000 & \(39\pm 1\) & \(79\pm 1\) & \(58\pm 1\) & \(78\pm 1\) \\ E\_BMC_8 & \(42\pm 1\) & \(123\pm 1\) & \(63\pm 1\) & \(104\pm 1\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Thermal properties determined based on DSC measurements of PCUUs, OCDs, and BMC. during glass transition, is introduced in this method [56; 57]. On the other hand, DMTA allows the determination of material properties as a function of stress, frequency, time, and/or temperature. In the presented study, we determine the glass transition temperature (T\({}_{\text{g}}\)) and the melting point (T\({}_{\text{m}}\)) of PCUUs using MDSC and DMTA (Table 4, Table 5, Figures 9 and 10, and Figures S55-S62 in the Supplementary Materials). To investigate T\({}_{\text{g}}\), MDSC and DMTA were used. These methods are more sensitive to changes occurring at the T\({}_{\text{g}}\) in comparison to DSC, in which the mentioned thermal \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**T\({}_{\text{g}}\) tan\(\delta\)**} & \multicolumn{2}{c}{**T\({}_{\text{g}}\) E\({}^{\prime}\)**} & \multicolumn{2}{c}{**T\({}_{\text{g}}\) E\({}^{\prime\prime}\)**} & \multicolumn{2}{c}{**T\({}_{\text{m}}\)**} \\ \cline{2-7}  & \({}^{\circ}\)**C** & \({}^{\circ}\)**C** & \({}^{\circ}\)**C** & \({}^{\circ}\)**C** \\ \hline E\_PCUU3000\_3.5 & \(-2\pm 1\) & \(-29\pm 1\) & \(-18\pm 1\) & \(51\pm 1\) \\ E\_PCUU3000\_3 & \(-7\pm 1\) & \(-33\pm 1\) & \(-22\pm 1\) & \(51\pm 1\) \\ E\_PCUU3000\_2.5 & \(-11\pm 1\) & \(-31\pm 1\) & \(-21\pm 1\) & \(49\pm 1\) \\ E\_PCUU3000\_2 & \(-15\pm 1\) & \(-33\pm 1\) & \(-23\pm 1\) & \(51\pm 1\) \\ E\_PCUU3000\_1.5 & \(-11\pm 1\) & \(-32\pm 1\) & \(-22\pm 1\) & \(57\pm 1\) \\ E\_PCUU5000\_3 & \(-16\pm 1\) & \(-31\pm 1\) & \(-23\pm 1\) & \(51\pm 1\) \\ E\_PCUU5000\_2 & \(-17\pm 1\) & \(-29\pm 1\) & \(-25\pm 1\) & \(50\pm 1\) \\ \hline \hline \end{tabular} \(T_{\text{g}}\) tan\(\delta\)—Tg based on Tan Delta. T\({}_{\text{g}}\) E\({}^{\prime}\)—Tg based on storage modulus. T\({}_{\text{g}}\) E\({}^{\prime\prime}\)—Tg based on loss modulus.  
\end{table} 
Table 4: T\({}_{\text{g}}\) and melting point based on DMTA. Figure 9: DMTA plots for (**a**) storage modulus and (**b**) Tan Delta as a function of temperature of PCUUs. transition was not detected. A higher molar excess of the IPDI caused an increase in the T\({}_{\rm g}\) (based on Tan Delta) from \(-\)15 \({}^{\circ}\)C in the case of E_PCUU3000_2, to \(-\)2 \({}^{\circ}\)C for E_PCUU3000_3.5 (Table 4 and Figure 9). This could be explained by the effect of main chain stiffness dependence on IPDI excess. In the case of more rigid polymer structures, containing a higher isocyanate content, a higher T\({}_{\rm g}\) was recorded. A similar tendency was observed for T\({}_{\rm g}\) based on the MDSC (Table 5); however, the trend was not so clear. DSC and MDSC (Table 3 and Figure 10) show consistently that T\({}_{\rm m}\) decreased with increasing isocyanate excess used in the synthesis.