Hui Zhao,Si-Qi Zhao,Guo-Hua Hu,Qun-Chao Zhang,Yang Liu,Chong-Xing Huang,Wei Li,Tao Jiang,Shuang-Fei Wang
A facile method was developed to synthesize a new type of polyhedral oligomeric silsesquioxane (POSS). It contained a single amine group and seven aliphatic moieties on its corners. FT-IR, 1 H-NMR, 13 C-NMR, 13 C- 1 H COSY, and 1 H- 1 H COSY confirmed that cages with eight corners were the main part of the product. This new POSS was used to modify the structure of hexamethylene diisocyanate trimer and then copolymerized with hexamethylene diisocyanate and poly (tetramethylene glycol) to get a serious of waterborne polyurethane (WPU)/POSS hybrid materials with low dielectric constants for microelectronics applications. The results showed that POSS particles were uniformly dispersed in the WPU dispersions. The WPU/POSS films did not show any macrophase separation, even when the POSS content was as high as 16%. As the POSS content increased from 0% to 16%, the tensile strength was increased from 2.3 to 7.3 MPa, the dielectric constant was decreased from about 2.9 to 2.0, and the thermal stability of the WPU/POSS was also improved.
Polyhedral oligomeric silsesquioxane (POSS) tethered fluorinated diblock copolymers including linear-shaped ap-POSS–PMMA-b-PDFHM and star-shaped s-POSS–(PMMA-b-PDFHM)16 are synthesized by octakis(dibromoethyl)POSS (POSS-(Br)16) and aminopropylisobutyl POSS (ap-POSS) initiating methylmethacrylate (MMA) and dodecafluoroheptylmethacrylate (DFHM). In THF solution, both diblock copolymers could self-assemble into 200 nm core/shell micelles with a POSS/PDFHM core and 70–80 nm PMMA shell. These micelles are able to produce typical films with a fluorine-rich top-surface and POSS-gathered sub-surface. Although PDFHM segments and POSS cages are competitively migrating onto the film surface, the migration of the PDFHM segments is actually improved by the POSS cages. Comparatively, the surface of the ap-POSS–PMMA-b-PDFHM film is much more rough and fluorine-rich than the s-POSS–(PMMA-b-PDFHM)16 film, therefore, the ap-POSS–PMMA-b-PDFHM film has higher viscoelasticity and higher oleophobicity, but a little lower hydrophobicity than the s-POSS–(PMMA-b-PDFHM)16 film. The hydrophobic application of both linear- and star-shaped topologies to glass, cotton fabric and stone substrates reveals that the treated samples exhibit superhydrophobicity for the cotton fabric (>150°) and obvious hydrophobicity for the stone and glass (>135°) in terms of resistance to water and other liquids like coffee, milk, coke and green tea. It is believed that the properties of self-assembled films and the hydrophobic applications are related closely to the topologies of block copolymers.
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