Effect of residue solvent in polybutylene-1 on the following phase transition after solvent vapor annealing for different time

Polybutylene-1 (PB-1) consisting of form II and I in different ratio was achieved by solvent vapor annealing pure form II polybutylene-1 for different time. X-ray diffractometer was used to observe the phase transition of the residue form II at room temperature after solvent vapor annealing. The results show that the phase transition speed is faster than that of the natural phase transition and changed from fast to slow. By FTIR, the volatilization process of n -hexane in PB-1 was observed. After PB-1 sample was treated with solvent vapor annealing for several minutes, n -hexane in PB-1 was saturated. In the following phase transition at room temperature, the time required for n -hexane to volatilize from PB-1 is the same which demonstrates that it is independent of the time of solvent vapor annealing. This phenomenon indicates that residue n -hexane still promoted the phase transition of the residue form II at room temperature. With the volatilization of n -hexane, the promotion gradually decreased until it disappeared. Therefore, it is not necessary to treat Form II PB-1 sample in solvent vapor annealing until completely phase transition to Form I in actual application because more than 75% transition is enough and the residue solvent will also accelerate phase transition. Graphical abstract