## 3 Results
### In Situ FTIR
#### 3.1.2 Simultaneous FTIR and SANS on PEGDME in Solution  
Unlike crystallization from bulk or melt, a variety of processes, such as the formation of polymer and solvent compounds, a physical gelation, or a liquid-liquid phase separation, may take place when polymers crystallize from solution, depending on the solvent type and polymer concentration and molecular weight [25]. PEGDME is a semi-crystalline polymer, soluble in water and compatible with most organic solvents. When PEGDME crystallizes from solution, crystallites grow as aggregates of small layers of lamellae with branching and splitting. The morphology of this hierarchical organization of structures over a wide length scale, between nm and um, can be resolved by SANS. In the crystalline state, PEGDME takes a regular helical conformation, which can be regarded approximately as a uniform (7/2) helix [26; 27]. When taking a long helical structure, PEGDME chains exhibit some sharp conformational regularity IR bands, such as the 1345 cm\({}^{-1}\) A\({}_{2}\) band [28; 29]. Thus, the combination between SANS and in situ FTIR is a powerful method for the study of the kinetics and morphology of polymer crystallization from solution. In Figure 4 we report the results of the DSC scan taken under nitrogen atmosphere between 50 \({}^{\circ}\)C and 10 \({}^{\circ}\)C from the solution of the PEGDME in dTHF with a cooling rate of 5 \({}^{\circ}\)C/min. The polymer crystallization occurs at about T\({}_{\text{C}}\) = 26-27 \({}^{\circ}\)C, with two peaks observed in the heat flow curve, an effect similar to that observed for the bulk crystallization of PEG [30]. Therefore, in order to investigate the change in conformation of PEGDME chains and the formation of polymer crystalline morphology at mesoscopic scale when passing through the T\({}_{\text{C}}\), we performed the simultaneous FTIR and SANS analysis of the hPEGDME in dTHF solution at 30 \({}^{\circ}\)C, above the T\({}_{\text{C}}\), followed by a rapid cooling to 12 \({}^{\circ}\)C, below the T\({}_{\text{C}}\). Figure 5 shows a selected range of the infrared spectra from the hPEGDME in dTHF at 30 \({}^{\circ}\)C (blue line) and at 12 \({}^{\circ}\)C (with the cyan and red lines indicating the initial and final stages, and the other lines in between depicting the time evolution of the spectrum at this temperature) in parallel with the spectrum of dTHF taken at 30 \({}^{\circ}\)C. Upon reaching the temperature of 12 \({}^{\circ}\)C, infrared spectra from the sample were collected every 30 s within a time interval of 35 min, to follow the kinetics for isothermal crystallization of polymer in solution. The time-resolved analysis clearly shows the evolution and transformation of the band at 1352 cm\({}^{-1}\), which is characteristic of amorphous polymer structure (single coil in solution) and well visible in the initial stage at 12 \({}^{\circ}\)C, into the bands at 1345 cm\({}^{-1}\) and 1364 cm\({}^{-1}\), which are characteristic of the helical conformation of polymer chain in the  
Figure 4: The thermal behavior of hPEGDME (M\({}_{\text{W}}\) = 20,000 g mol\({}^{-1}\)) in solution of dTHF (\(\phi_{\text{pol}}\) = 2%) during the crystallization process at a rate of 5 \({}^{\circ}\)C/min. crystalline state and well visible in the final stage at 12 \({}^{\circ}\)C. All other bands, corresponding to either the amorphous conformation in the initial stage or the helical conformation in the final stage, correspond to frequencies reported for the PEG system [31; 32]. The polymer morphology in solution at 30 \({}^{\circ}\)C and 12 \({}^{\circ}\)C in the initial and final stages of crystallization was investigated by SANS in parallel with the FTIR analysis. Figure 6 reports the corrected and calibrated SANS results collected simultaneously with the acquisition of the infrared spectra. The power law exponents (Q\({}^{-p}\)) specific for different polymer morphologies are given.