Effect of hydroxyl-terminated poly(fluoroalkyl methacrylate) main-chain length on the microphase separation of waterborne fluorinated polyurethane

Waterborne fluorinated polyurethanes (WFPUs) based on hydroxyl-terminated poly(fluoroalkyl methacrylate)s (HTPFMAs) with different main-chain lengths were synthesized. The structure of HTPFMA was characterized using 1 H NMR spectroscopy, measurements of hydroxyl values and gel permeation chromatography. The microstructures of WFPUs were investigated using Fourier transform infrared spectroscopy, which indicated that hydrogen bonding interactions in hard segments of WFPUs were enhanced by the introduction of HTPFMA and increased with increasing main-chain length of HTPFMA. The results of X-ray diffraction demonstrated that increasing the main-chain length of HTPFMA resulted in an increase of crystallinity in hard segments. Differential scanning calorimetry revealed that the melting temperature of micro-crystallites in hard segments and the microphase separation increased with an increase of HTPFMA main-chain length. Dynamic mechanical analysis and scanning electron microscopy also confirmed that HTPFMA with longer main-chain length can promote the extent of microphase separation of WFPUs between soft and hard domains. The mechanical properties of WFPUs were improved due to the increase of microphase separation with increasing HTPFMA main-chain length. © 2018 Society of Chemical Industry