Transparent and Durable Antismudge Polyurethane Coatings with Octadecyl Chlorosilane-Enhanced Bihydroxypropyl PDMS Polymer Brushes

Abstract

A liquid-like poly(dimethylsiloxane) (PDMS) brush as an environmentally friendly, low surface energy modifier has a significant effect on improving the antismudge properties of coatings. However, in order to obtain a sufficient length of freely mobile chain segments to meet the liquid repellency, expensive single-terminal functionalized PDMS has to be chosen in the preparation of antismudge coatings. In this work, double-terminal functionalized PDMS was employed to fabricate antismudge polyurethane (PU) coatings with the help of alkyltrichlorosilane (RSiCl 3 ). That is, bihydroxypropyl PDMS (BHPDMS) was terminated with RSiCl 3 , further grafted onto acrylic polyol chains using its residual Si−Cl bonds, and subsequently cured with an isocyanate trimer. Effects of the molecular weight of BHPDMS (M n = 1000, 2000, 4300, and 10,000 g/mol) and the type of RSiCl 3 (R = methyl, dodecyl, octadecyl) on the surface wettability of antismudge PU coatings were investigated. Among them, octadecyltrichlorosilane (OTS) terminated BHPDMS 4300 exhibited the lowest water contact angle hysteresis (10.1°), which was even lower than that of the control samples via direct addition of monohydroxypropyl PDMS or BHPDMS 4300 . The antismudge PU coating also presented high transparency (90.5%) and excellent liquid repellency against various low surface tension liquids. Even after friction with steel wool, the coating can still maintain excellent antismudge performance. The results also showed enhancement of OTS on the liquid repellency of antismudge PU coatings, indicating its synergistic effect with BHPDMS brush. It is envisioned that OTS-terminated BHPDMS additive provides an avenue to fabricate cost-effective transparent antismudge PU coatings.

Waterborne Polyurethane Modified with the Hydroxy Silicone Oil for Improving its Thermal, Water Resistance, and Mechanical Properties

“…This was because the film-forming ability of WPU emulsion becomes stronger after modification, and the formed film cracks are significantly reduced, it is difficult to form largearea layered cracks. At the same time, the modification samples also enhance the lubricity of the emulsion, improve the cohesion inside the film, and weaken the impact force and fracture force of the brittle fracture section, and it is difficult to form a large area of layered folds [34][35] . the microphase separation of WPU can be observed through the AFM phase diagram [37] .…”

Reducing High-Molecular-Weight Oligomers in Biobased Pentamethylene Diisocyanate Trimers

“…Consequently, they require processing to form various oligomers. − Among these, isocyanurate trimers have become one of the most extensively used curing agents in the field of PU coatings because of their stable six-membered ring structure. Current research on isocyanate trimers primarily focuses on comparing the performance of coatings prepared from them, including their thermal stability, weather resistance, acid and alkali resistance, and aging resistance. , However, limited research has been conducted on the properties of isocyanate trimers themselves. Because of the continuous polymerization reaction during the synthesis of isocyanurate trimers, the resulting polymer invariably comprises a mixture of several oligomers, including trimers (n = 3), pentamers (n = 5), heptamers (n = 7), or high-molecular-weight oligomers ( n ≥ 9, where n is the number of monomers included).…”