# Synthesis of Shape-Memory Polyurethanes: Combined Experimental and Simulation Studies
## 2 Materials and Methods
### Characterization Techniques  
The \({}^{1}\)H NMR and \({}^{13}\)C NMR spectra were recorded in CDCl\({}_{3}\) on a Varian VXR 400 MHz Spectrometer (Palo Alto, CA, USA) and analyzed with MestReNova v.6.2.0-7238 (Mestrelab Research S.L) software. Time-of-flight mass spectrometry (MALDI-TOF) measurements were performed on a Bruker UltraFlex MALDI TOF/TOF Spectrometer (Bremen, Germany) in a linear or reflection mode using a DHB (2,5-dihydroxybenzoic acid) matrix and Bruker Peptide Calibration Standard (1047.19-3149.57 Da) as a calibrant, and analyzed with Polymerix v.2.0 (Sierra Analytics Inc.) software. Exemplary table and graph showing the results of the performed experiment are shown in Table S1 and Figure S29, Supplementary Materials. The GPC analysis was performed using a Malvern Nicotek GPCMax TDA 305 (Malvern Panalytical, Malvern, UK). The chromatograph was equipped with a 30 cm [PERSON] mixed bed column with an inside diameter of 7.8 mm (Jordi Labs, Mansfield, MA, USA). The system was calibrated with a polystyrene standard. Approximately 2 mg of a solid sample was dissolved in 1.5 mL of dichloromethane. After complete dissolution, the solutions were passed through a syringe filter with a PTFE membrane with a 0.2 \(\upmu\)m pore size. The flow rate of dichloromethane was set as 1 mL\(\cdot\)min\({}^{-1}\) and the temperature was set as 30 \({}^{\circ}\)C.  
ATR-FT-IR spectra were recorded on a Thermo Scientific Nicolete i55 FTIR spectrometer using an ATR iD7 accessory. Thirty-two scans were performed for each sample with a resolution of 4 cm\({}^{-1}\). A sample of PCUU_3000_3 was also measured with the transmittance mode using a very thin film of the sample. Measurements of differential scanning calorimetry (DSC) were performed with the use of TA Instruments Q1000 DSC. Samples were investigated with a constant heating and cooling rate of 10 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) at the temperature range from 90 \({}^{\circ}\)C to 150 \({}^{\circ}\)C. The purge cell gas was nitrogen with a flow rate of 50 mL\(\cdot\)min\({}^{-1}\). A total of 15-25 mg of each sample was loaded on an aluminium pan sealed with a pinhole cap. Modulated differential scanning calorimetry (MDSC) was performed using a TA Instruments Q100 DSC at the temperature range from \(-\)90 \({}^{\circ}\)C to 150 \({}^{\circ}\)C. The four runs of heating were performed with each material: first heating run, second heating run of previously heated sample, first heating run of the elongated sample with 100% strain andthe second heating run of the previously elongated sample after its return to the primary shape. The sample was loaded on an aluminium pan sealed with a pinhole cap. The heating rate was 3 K \(\times\) min\({}^{-1}\), modulation amplitude was 0.48 \({}^{\circ}\)C, and modulation period was 60 s.  
Dynamic mechanical thermal analyses (DMTA) was performed with a DMTA Q800 machine from TA Instruments, New Castle, DE, USA. Measurements were performed at a fixed frequency of 1 Hz, from -90 \({}^{\circ}\)C to 150 \({}^{\circ}\)C with a heating rate of 3 K \(\times\) min\({}^{-1}\). Loading was carried out in the tensile mode with an amplitude of 20 \(\upmu\)m in the controlled force mode. Tensile tests were performed on an Instron 5566 equipped with a 100 N cell load using the standard dumbbell-shaped samples (ISO 527-2/1 BB) cut from films. The average value of the tensile strength (\(\sigma\)), elongation at break (\(\epsilon\)) and Young's modulus (E\({}_{\rm Young}\)) for each type of material was determined from at least five specimens. The gel fraction contents (G\({}_{\rm f}\)) and the mass equilibrium degrees of swelling (Q\({}_{\rm m}\)) were calculated based by swelling the films in 500-fold excess (related to the sample weight) of chloroform for 72 h at RT, with subsequent drying overnight. The endpoints of swelling and drying were reached when constant weights were obtained.