Synthesis and properties of castor oil‐based polyurethane containing short fluorinated segment

This study successfully incorporated a short‐segment fluorine‐containing chain extender (2,2,3,3‐tetrafluoro‐1,4‐butanediol [TF]) into castor oil‐based polyurethane (COPU) to synthesize TF/COPUs. The interactions between TF and COPU components were identified by Fourier transform infrared and X‐ray photoelectron spectroscopies, the results revealed that the increase in the TF content increased the van der Waals forces in CF…CO and the hydrogen bonding force in CF…HN. Atomic force microscopy indicated that the addition of more TF contributed to a higher level of microphase separation in the TF/COPUs. Thermogravimetric analysis showed that the TF component can enhance the thermal resistance of TF/COPUs. Differential scanning calorimetry and dynamic mechanical analysis indicated that the glass transition temperature (Tg) of TF/COPUs increased with the TF content. The stress–strain testing showed that the tensile strength and elongation at break values decreased with the TF content. This tensile behavior may be due to the molecular weight of a TF/COPU decreased with the TF content as evidenced by the gel permeation chromatography results. The hydrolytic degradation tests of dipping TF/COPUs in 3 wt% NaOH solution indicated that TF could lower the surface free energy and enhance the degradation stability of TF/COPUs.