Study on siloxane-modified polyurethane dispersions from various polydimethylsiloxanes

In this work, various polydimethylsiloxanes (PDMS) are incorporated with isophorone diisocyanate (IPDI), 2,2-bis(hydroxymethyl)propionic acid (DMPA), and poly(tetramethylene oxide) (PTMO) by the prepolymer process to synthesize a series of siloxane-modified polyurethane dispersions (PUDs) with 35 wt % solid content, viscosities of 20-100 cps, and particle sizes of 40-130 nm. Hydrophobic PDMS was introduced into the PU chain either based on random distribution or through the block segment arrangement. We also establish the composition-property relationship of PDMS-PUD, which includes PDMS's type and molecular weight and PDMS-PUD film's contact angle and mechanical property. The tensile strength of PDMS-PUD film is decreased with increasing amount of PDMS. Scanning electron microscopy for chemical element analysis indicated that PDMS migrated to the surface much more easily in the block arrangement than in the random distribution. Also, some PDMS-PUD films show a peau-like surface, so their PUDs are considered promising to be used in processes for textiles. (c) 2005 Wiley Periodicals, Inc.