title: Formation of superhydrophobic microspheres of poly(vinylidene fluoride- hexafluoropropylene)/graphene composite via gelation.
abstract: We report on the spontaneous formation of superhydrophobic poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/graphene composite microspheres with uniform size via gelation. When the suspension of PVDF-HFP/graphene (0.25 wt. % with respect to PVDF-HFP) in DMF adsorbs water vapor, it changes to a hybrid gel. A dried porous gel is obtained after solvent exchange and freeze drying. Morphology characterization shows that this hybrid gel is composed of PVDF-HFP/graphene microspheres with a diameter of 8-10 μm. In contrast, PVDF-HFP solution gives rise to a cellular microstructure following the same experimental procedures. We further elucidate the formation mechanism on the basis of the characterization by freeze fracture transmission electron microscopy, X-ray diffraction, and differential scanning calorimetry characterizations. Furthermore, contact angle measurements of water on PVDF-HFP/graphene indicates that the hydrophobic nature of PVDF-HFP combined with the micro/nanoscale hierarchical texture creates a superhydrophobic surface. Such superhydrophobic microspheres may have potential applications as water-repellent catalyst-supporting materials.
authors.affiliation: Department of Chemistry, Renmin University of China, Beijing, People's Republic of China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Dao-an
authors.initials: DA
authors.lastname: Zha
authors.forename: Tingting
authors.initials: T
authors.lastname: Du
authors.forename: Shilin
authors.initials: S
authors.lastname: Mei
authors.forename: Zujin
authors.initials: Z
authors.lastname: Shi
authors.forename: Zhaoxia
authors.initials: Z
authors.lastname: Jin
mesh_terms: D000042:Absorption; D005240:Feasibility Studies; D005782:Gels; D006108:Graphite / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008863:Microspheres; D053761:Nanocomposites / Q000737:chemistry*; D011145:Polyvinyls / Q000737:chemistry*; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D005782:Gels; D011145:Polyvinyls; C545920:poly(vinylidene fluoride-co-hexafluoro propylene); D014867:Water; D006108:Graphite