Explaining discussion-induced cooperation.

In a social dilemma game, a period of discussion among subjects substantially increases the incidence of cooperative choices. We conducted two experiments in an effort to explain this effect. Experiment 1 tested and rejected the hypothesis that discussion of the dilemma problem promotes generalized norms in favor of cooperation. Content analysis of discussion sessions in Experiment 1 suggested that promises to cooperate are important in an explanation of discussion's effect. Experiment 2 showed that promises to cooperate substantially increased cooperation rates, but only when everyone in the discussing group promised. We discuss one model in which discussion promotes group identity (as indicated by consensual promising) and therefore cooperation, and another in which discussion provides an opportunity for promise making, which—at least when it is universal—explains discussion's effect without any involvement of group identity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Easily Processable and Programmable Responsive Semi‐Interpenetrating Liquid Crystalline Polymer Network Coatings with Changing Reflectivities and Surface Topographies

The fabrication of stimulus‐responsive coatings that change both reflectivity and topography is hampered by the lack of easy processable, patternable, and programmable elastomers. Here, an easily applied reflective coating based on a semi‐interpenetrating polymer network composed of a liquid crystal elastomer and a liquid crystal network (>15 wt%) is reported. The reflective wavelength of these polysiloxane elastomer photonic coatings can be readily programed by the concentration of chiral reactive mesogen dopant that forms the network. The coatings show a fast and reversible decrease in reflection band intensity with increasing temperature, which can be tuned by the polymer network density. In addition, hierarchical surface relief structures are prepared, which can be reversibly changed with temperature.     

3D Helix Engineering in Chiral Photonic Materials

Engineering the helical structure of chiral photonic materials in three dimensions remains a challenge. 3D helix engineered photonic materials are fabricated by local stratification in a photopolymerizable chiral nematic liquid crystal. The obtained chiral photonic materials reflect both handedness of circular polarized light and show super‐reflectivity. Simulations match the experimentally observed photonic properties and reveal a distorted helical structure. 3D engineered polymer films can be made that reflect both left‐ and right handed circular and linear polarized light dependent and exhibit a changing color contrast upon altering the polarization of incident light. Hence, these 3D engineered photonic materials are of interest for new and emerging applications ranging from anti‐counterfeit labels and data encryption to aesthetics and super‐reflective films.