Synthesis of Castor Oil‐Based Waterborne Polyurethane with Improved Properties via Adjusting PBA/CO Soft Segment Ratio

Abstract

In this study, dimethylol propionic acid (DMPA) and ethoxylated polymer diol (N120) are incorporated as composite hydrophilic groups to synthesize a series of castor oil‐based waterborne polyurethane (CWPU) nano‐emulsions. The properties of the nano‐emulsions with different ratio of polybutylene adipate (PBA) and castor oil (CO) soft segments as well as their film are investigated systematically. Fourier infrared spectroscopy (FTIR) confirms that CO was successfully introduced into the waterborne polyurethane (WPU) structure. The result indicates that the maximum contact angle of the film is 75.51° with a 7/3 molar ratio of PBA/CO. Thermal Gravimetric Analyzer (TGA) and Dynamic thermomechanical analysis (DMA) tests show that the thermal stability of the films has gradually improved with the increase of castor oil content. The content of castor oil in CWPU also affects the mechanical properties of the film. The tensile strength of the film reaches 23.2 MPa, and the elongation at break is 1460.7 %, when the molar ratio of PBA/CO is 9/1. Atomic force microscopy (AFM) is used to express the surface morphology of CWPU films. The films surface become rougher due to the introduction of CO. This work combines castor oil and water‐based systems to provide a relatively simple preparation method to synthesize CWPU nano‐emulsions, which can be used in environmental protection coatings and adhesives, and has broader application prospects.

Environmentally friendly plant‐based waterborne polyurethane for hydrophobic and heat‐resistant films

“…Before the FTIR spectrum test, the film sample needs to be dried in an oven to remove water. It can be seen from Figure 5a that the characteristic of the hydroxyl absorption peak in CO is 3429 cm −1 , which indicates that it has participated in the reaction and is introduced into the WPU main chain 28 . There is no absorption peak at 3400 cm −1 , indicating that the hard segment urethane bond has been completely formed on the NH bond.…”

“…It can be seen from Figure 5a that the characteristic of the hydroxyl absorption peak in CO is 3429 cm À1 , which indicates that it has participated in the reaction and is introduced into the WPU main chain. 28 There is no absorption peak at 3400 cm À1 , indicating that the hard segment urethane bond has been completely formed on the N H bond. The absorption peak near 3340 cm À1 is caused by N H tensile vibration in the urethane segment ( NH CO O).…”

Preparation and antibacterial study of waterborne polyurethane modified with lysine and quaternary ammonium salt

“…In addition, the large dispersion index (PDI) of WKPU emulsions can be interpreted as an increase in the degree of cross-linking that hinders the movement of molecular chains, thus affecting the uniform growth of molecular chains and the inhomogeneity of molecular lengths and branching. 32…”

Demonstration of temperature-sensitive paints with rigorously controlled thickness applied to variously shaped metal substrates with a highly stable connection based on a demulsification-induced fast solidification strategy

“…It is interesting to note that there are four stages in the thermal degradation procedure of the WPU/PCD (2 h) film, which are in direct agreement with the literature. 42,50 The first mass loss step at a temperature below 210.02 °C is mainly attributed to the moisture absorbed in the WPU/PCD (2 h) film. The second stage occurred in the temperature range between 210.02 °C and 298.25 °C, which was mainly ascribed to the decomposition of the hard segment for the WPU/PCD (2 h) film.…”