Nanostructured Polyurethane/POSS Hybrid Aqueous Dispersions Prepared by Homogeneous Solution Polymerization

Abstract

Aqueous polyurethane dispersions were prepared with 4−10 wt % of functionalized polyhedral oligomeric silsesquioxanes (POSS) via homogeneous solution polymerization in acetone followed by solvent exchange with water. The use of acetone as the initial polymerization solvent allowed for the facile incorporation of both diamino and dihydroxy functional POSS monomers in a homogeneous reaction environment. After addition of water and removal of the acetone, stable dispersions with unimodal particle sizes were obtained. The incorporation of the POSS monomers did not have a significant effect on the dispersion's properties; however, the physical properties of the isolated polymers did display significant changes, with notable increases in storage modulus, T g, complex viscosity, and surface hydrophobicity. These changes were attributed to the incorporation of the POSS residues into the polyurethane hard segment domains found. Though no sign of any gross phase heterogeneity due to the inclusion of POSS moieties was detected by either thermal characterization or wide-angle X-ray diffraction (WAXD), a significant change was observed by atomic force microscopy (AFM) when the samples were recast from organic solvent.

Surface energetics, dispersion, and nanotribomechanical behavior of POSS/PP hybrid nanocomposites

“…These findings are consistent with previously reported studies showing increased surface hydrophobicity for other POSS/polymer systems and POSS molecules with fluorinated alkyl chains attached to the POSS cage. 12,[21][22][23][24] Surface dynamics were further studied via dynamic water contact angle analysis. The advancing (h a ) and receding (h r ) water contact angles were measured and their difference, the contact angle hysteresis (h h ), was calculated (Table 4).…”

“…In general, hybridization of an organic polymer matrix with inorganic POSS results in improved thermal and mechanical properties along with increase in oxidative and flame resistance. [3][4][5][6][7][8]11 Recently Nanda et al 12 synthesized well dispersed polyurethane/POSS hybrid materials utilizing a solution polymerization process. Ordered morphologies with homogenously distributed POSS domains ($100-150 nm) were observed.…”

POSS/Polyurethane Hybrids and Nanocomposites: A Review on Preparation, Structure and Performance

“…Using the acetone method with 3-(2-aminoethyl) amino propyl-heptaisobutyl-POSS (diamino-POSS), 2,3-propanediol propoxy-heptaisobutyl-POSS (diol-POSS), and other raw materials, Nanda et al 40 synthesized POSS/PU hybrid dispersions, according to the synthesis steps shown in Figure 4. All the PU-POSS dispersions studied were stable for more than 6 months.…”

Modification of Thermoplastics with Reactive Silanes and Siloxanes

“…As with other polymer systems, many of the POSS hybrids do yield elastomeric PU with improvements in physical and thermal properties at relatively low levels of POSS incorporation. The waterborne PU hybrid dispersions were synthesized by incorporating amino-and hydroxyl-terminated POSS macromers into the PU ionomeric backbones, using a homogeneous solution polymerization, followed by a solvent exchange with water (i.e., the "acetone process") (Nanda & Wicks 2006). The absence of crystalline domains evidenced the incorporation of POSS macromer in the PU hard segments.…”