Hydrophilic polyurethanes, water solubility

SMPs can be triggered by water or moisture due to the plasticizing effect of water molecules, which increases the flexibility of macromolecule chains . If a SMP has a hydrophilic or water soluble ingredient, the shape recovery can be accelerated. Pyridine unit, which is responsive to moisture, can be used to improve the moisture absorption in polyurethane. Hu and co-workers introduced pyridine unit into SMPU by N-bis(2-hydroxylethyl) isonicotinamine (BINA) and prepared moisture-responsive SMPU with high strain recovery and recovery speed. SMPs sensitive to their suitable solvents can be obtained which are similar to hydrophilic SMPs that are sensitive to water/moisture. ... 

Conditions are established for the preparation of hydrophilic and water-soluble polyurethane elastomers based on ADMH and other hydrazine derivatives, 1,6-hexamethylene diisocyanate and poly(tetramethylene oxide) (MW 1000 g/mole)... 

Interfacial behavior of different silicones was extensively studied, as indicated in Section 3.12.4.6. To add a few more examples, solution behavior of water-soluble polysiloxanes carrying different pendant hydrophilic groups, thus differing in hydrophobicity, was reported.584 A study of the aggregation phenomena of POSS in the presence of amphiphilic PDMS at the air/water interface was conducted in an attempt to elucidate nanofiller-aggregation mechanisms.585 An interesting phenomenon of the spontaneous formation of stable microtopographical surface domains, composed primarily of PDMS surrounded by polyurethane matrix, was observed in the synthesis of a cross-linked PDMS-polyurethane films.586... 

To further explore the effect of the polarity of the molecule on its extractability, we studied the extraction of a water-soluble dye molecule by polyether polyurethane (hydrophobic) and a hydrophilic polyurethane (HPUR). The dye was bromothymol 2005 by CRC Press LLC... 

All but the polyurethane are characterized by methylene backbones with ligands that are sufficiently polar to make them water soluble. Thus, upon dissolution in water, the polarity of the water molecule associates with the polarity of the acrylic or acrylamide groups to form a shell. We discussed hydrophilic polyurethanes that are typically cross-linked and are not (but could be) considered effective thickeners. Nevertheless they too have hydration shells developed due to the influence of the polyethylene glycol backbone. The extent of that shell is determined by the hydro-philicity of the ligand the acrylic > acrylamide > alcohol > polyurethane. The volume... 

Multi-Grout AV-202 (Avanti International) is a similar product, also of relatively high viscosities, described as water-soluble, hydrophillic polyurethane prepolymers. Gel time characteristics are shown in Fig. 11.46. 

Cationic, anionic, and amphoteric surfactants derive their water solubility from their ionic charge, whereas the nonionic hydrophile derives its water solubility from highly polar terminal hydroxyl groups. Cationic surfactants perform well in polar substrates like styrenics and polyurethane. Examples of cationic surfactants are quaternary ammonium chlorides, quaternary ammonium methosulfates, and quaternary ammonium nitrates (see QuARTERNARY ammonium compounds). Anionic surfactants work well in PVC and styrenics. Examples of anionic surfactants are fatty phosphate esters and alkyl sulfonates. 

---