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Abstract
Silicon-based polyurethanes have a wide range of applications in many fields like automobiles, lubricants, adhesives, etc. due to their elastomeric properties. In this work, two different types of polyurethanes with different structures were synthesized: (i) polypropylene glycol-based polysiloxane-polyurethane and (ii) castor oil-based polysiloxane-polyurethane. The first one was synthesized by reacting polypropylene glycol (PPG), hydroxyl-terminated (polydimethylsiloxane) (PDMS) and different isocyanates such as isophoronediisocyanate (IPDI), Hexamethylenediisocyanate(HMDI) and Toluene diisocyanate(TDI) while for the other one instead of PPG, castor oil has been used. As the other two monomers are the same in both the polymers, variation in properties in these two polymers will be mainly due to the presence of PPG and castor oil-based moieties. Chemical and instrumental characterization techniques were used to determine the chemical and physical properties of both polyurethanes. For chemical characterization percentage of isocyanate, acid value and hydroxyl group have been carried out. Instrumental techniques have been used for the determination of functional groups (FTIR) and the average molecular weights of the polymers (GPC). The thermal properties were determined using a thermogravimetric analysis technique. These polyurethanes were coated on mild steel panels, silicon wafers and films were cast in the teflon mold. Scratch hardness, pencil hardness, and adhesion methods have been used for the determination of properties of coated panels, while chemical resistance properties of coatings and castings were found out using different chemical techniques. Properties of both the PUs have been compared. Silicon-based polyurethanes were mostly hydrophobic; therefore, it can be used where this type of property is required.