Synthesis and Properties of End-Branched Polyurethane Thickeners With Multi-Tail Chain Structure

Abstract

Hydrophobically modified ethoxylated urethane (HEUR), an associative thickener that regulates viscosity distribution within the system, has advanced considerably in its synthesis, associative mechanism, aggregation behavior, and rheological control. The majority of research on HEUR predominantly concentrates on the hydrophobic structure featuring a singular tail at the terminus. In this study, a series of HEURs with multi-tailed hydrophobic chain structures at the end were prepared by hydrophobically modifying ethoxylated polyurethanes using terminally branched hydrophobic alcohols with multi-tailed chains (PU-OH_2C–6C) as a capping agent. The hydrophobic terminus is adorned with many hydrophobic chains. In contrast to HEUR with a singular hydrophobic chain, this approach constructs a more compact network, facilitating rapid and homogeneous dispersion in water while demonstrating superior thickening efficiency. The structure of PU-OH_2C–6C was analyzed using FTIR, ¹H-NMR, and HPLC-MS/MS. The successful synthesis of the capped product HEUR was confirmed using 1H-NMR, FTIR, and DLS The rheological properties and thermal stability of the four HEUR polymers were assessed using a rotational viscometer and thermogravimetric analyzer. Concurrently, the influence of terminal branching degree on the thickening characteristics of HEUR was examined, offering valuable insights into the structural flexibility of the synthesized HEURs, particularly regarding the tunability of terminal hydrophobic chain quantity.