ABSTRACT
This corrects the article DOI: 10.1103/PhysRevLett.116.118301.
ABSTRACT
This corrects the article DOI: 10.1103/PhysRevLett.116.118301.
ABSTRACT
In simulations and experiments, we study the drying of films containing mixtures of large and small colloidal particles in water. During drying, the mixture stratifies into a layer of the larger particles at the bottom with a layer of the smaller particles on top. We developed a model to show that a gradient in osmotic pressure, which develops dynamically during drying, is responsible for the segregation mechanism behind stratification.
ABSTRACT
We report the synthesis of the first organo-POM with thermoresponsive properties. Our concept will provide chemists with a new tool to design POMs whose solubility is reversibly controllable through an external stimulus. POM-polymer TBA(7)[POM]-poly(N,N-diethylacrylamide) (POM-PDEAAm), was prepared by grafting PDEAAm-NH(2) (obtained by RAFT polymerization) onto the activated Dawson acyl-POM, α(2)-[P(2)W(17)O(61)SnCH(2)CH(2)C(=O)](6-). Extensive MS analysis was used to monitor the chain-functionalization steps and to confirm the formation of the hybrid. Aqueous solutions of the (NH(4))(7)[POM-PDEAAm] exhibited a LCST of 38 °C. Thus, the solubility/aggregation of the hybrid was reversibly controlled by changing the temperature. Above 38 °C, the solution became cloudy, and cleared again upon cooling. Dynamic light scattering (DLS) revealed the formation of small aggregates in the range 100 nm. We assumed that the charged POM head units prevented the formation of the larger-scattering aggregates that are usually observed for PDEAAm, and promoted the formation of micelle-like structures. The conjugate exhibited a temperature transition, which was different from that of the polymer and depended on the counterions associated with the POM. This result demonstrates the potential for merging organic (in this case, polymer) and inorganic structures to afford materials that exhibit new properties.
