The re-entrance of poly­(N,N-diethylacrylamide) (PDEA) in D2O/d-ethanol mixtures (i.e., the coil-to-spherical aggregates-to-coil transition) has been observed at 27 °C by small-angle neutron scattering (SANS). PDEA has a lower critical solution temperature (LCST) phase diagram in the D2O-rich region and is soluble in the D2O-poor region for all of the observed temperature ranges. Its spinodal temperature decreases first from 33.5 °C in pure D2O to 26.7 °C in 80% D2O/20% d-ethanol and then increases to 283.1 °C in 50% D2O/50% d-ethanol. With the further decrease of D2O content, PDEA dissolves well, and its phase boundary can no longer be observed by SANS. Therefore, at 27 °C, PDEA dissolves as random coils when the D2O content is higher than 90% and then collapses and aggregates to form the globule phase in 20% D2O/80% d-ethanol; finally, it reswells and behaves as random coils again with excluded volume in the D2O-poor region. The ternary random phase approximation model (RPA) is used to analyze the SANS profiles, and three Flory–Huggins interaction parameters (χPDEA–d‑ethanol, χPDEA–D2O, and χ d‑ethanol–D2O) are obtained. When a small amount of d-ethanol is added to the system, it has a strong interaction with D2O, so it directly gets distributed into the water structure and makes a negative contribution to the dissolution of PDEA (χ d‑ethanol–D2O is much smaller than χPDEA–d‑ethanol and χPDEA–D2O). With the addition of more d-ethanol, its interaction with water becomes weaker, but still stronger than those between PDEA–D2O and PDEA–d-ethanol. Neither d-ethanol nor D2O wants to help the dissolution of PDEA in the first place, until the structure of mixed solvents tends to be pure d-ethanol in the D2O-poor region.

Graphene sheets were successfully functionalized with 4-nitrophenyl diazonium (NPD). Two dimensional Raman analysis demonstrated that the reaction preferred to happen on single-layer graphene rather than bi-layer or multi-layer, and the edges of graphene were more reactive than the central areas. Atomic force microscopy (AFM) indicated the aryl groups were covalently bonded to one side of the graphene basal plane in a perpendicular configuration. Transmission electron microscopy (TEM) and selected area electron diffraction (SAED) manifested that the modified graphene maintained the hexagonal symmetry but its microstructure changed. The main change was that the crystal lattice expanded compared with that of pristine graphene. Meanwhile, for the first time, a crystal lattice constant d z 5.30A of functionalized graphene was obtained, which was approximately twice that of the pristine graphene's crystal lattice constant. This implied that the modified graphene had a super-lattice microstructure. Furthermore, the fast Fourier transform (FFT) of the modified graphene verified the formation of the super-lattice structures, and density functional theory (DFT) calculations showed the stability of the super-lattice structures. These modifications-elongation of crystal lattice constant and formation of super-lattice structures-may induce different electronic structures in graphene.