Synthesis and Characterization of Branched, Functional, Aqueous Polyurethane Dispersions for Self-crosslinking or Two-Component Textile Coatings
M.Sc. Thesis, July 2017
Assoc. Prof. Dr. Volkan Patoglu(Thesis Advisor), Prof. Dr. Erhan Budak, Assoc. Prof. Dr. Kemalettin Erbatur, Assoc. Prof. Dr. Mehmet Ismet Can Dede (Izmir Institute of Technology), Asst. Prof. Dr. Hande Argunsah Bayram (Acibadem University)
Date & Time: 24 July 2017 – 10:00 A.M
Place: FENS L067
Keywords: Polyurethanes, Waterborne dispersions, Branching, Functional polymers, A2 + B3 polymerization, Textile coatings
Waterborne polyurethane dispersion technology has been increasingly becoming significant in the market of environmentally friendly materials for advanced coating and adhesive applications due to their high performance and zero or near zero volatile organic content (VOC) in recent decades. Although the versatile chemistry of polyurethanes enables one to design high performance coating, adhesive or elastomeric materials for a wide range of applications, current synthetic routes for linear polyurethanes have limitations in the introduction of chemical functional groups on the polymer backbone. The present study focuses on the synthesis and characterization of waterborne, branched polyurethanes with a multitude of functional end-groups via the oligomeric A₂ + B₃ methodology. While the waterborne nature of final products makes them user and environmentally friendly, the presence of functional end-groups makes them suitable coating and adhesive materials for a variety of surfaces, specifically textiles. In this thesis, one-component and self-crosslinking, or two-component, amino- or silane functional polyurethane dispersions were synthesized and examined in detail. The influence of the degree of branching, nature of the soft segment and chemical structure of end-groups on the dispersion properties and thermo-mechanical properties of elastomeric films obtained from these dispersions was investigated systematically. Decreasing the A2:B3 ratio followed by silane functionalization and self-crosslinking resulted in stiffer films and coatings, due to higher crosslinking density. On the other hand, crosslinking of amino-functional PUs with polyisocyanate compounds in a two-component waterborne system resulted in enhanced mechanical and thermal properties as a function of the degree of cross-linking.
Upon the synthesis and characterization of branched, functional PU dispersions and films, pure wool and wool/polyester blend fabrics were coated with selected PU dispersions in an attempt to improve wrinkle and crease recovery of fabrics. While half grade improvement was achieved with branched PU dispersions with urea, silane and amino functionalities on pure wool surfaces, wrinkle resistance of wool/polyester blend fabrics was enhanced at least one grade with due to better compatibility of polyester containing wool fabric with polyester-based PU coatings.