897599-10-9Relevant academic research and scientific papers
Mesomorphism and shape-memory behavior of main-chain liquid-crystalline co-elastomers: Modulation by the chemical composition
Garcia-Marquez, Alfonso Ramon,Heinrich, Benoit,Beyer, Nicolas,Guillon, Daniel,Donnio, Bertrand
, p. 5198 - 5210 (2014/09/17)
The mesomorphic behavior, shape shifting, and shape-memory types of two homologous series of main-chain liquid-crystalline co-elastomers (MC-LCEs) with composition-tunable transition temperatures and mesophases structures are reported. The weakly cross-linked macromolecules were prepared in a one-step procedure by the versatile platinum-catalyzed hydrosilylation reaction between siloxane oligomers (linear spacers and netlike point molecules) and liquid-crystalline binary mixtures, composed of defined proportions of divinylic monomeric mesogens. First, the two sets of alternated, linear copolymers with disiloxane or trisiloxane chain extender, respectively, were investigated. They either exhibit both smectic C (SmC) and nematic (N) phases or a single SmC phase, the nature of which being dictated by the length of the inserted siloxane moieties, and the temperatures ranges regulated by the composition of the mesogenic mixture (mesogens ratio). As anticipated, the thermal behavior of the corresponding co-elastomers is not greatly affected by the weak reticulation (less than 5% w/w), whose transition temperatures (from the ambient to ca. 100 °C) and mesophases types (SmC and N) are quasi-replicated from the polymers and still majority governed by the intermingling of the constitutive components (mesogens ratios, siloxane, and comonomers). Moreover, these MC-LCEs exhibit two types of shape-memory behaviors, which are imposed selectively by the nature of the siloxane extender and which are understood in relation to the mesophases' structures. The combination of small-angle X-ray scattering and thermoelastic experiments gives some fundamental insights into the relationships between molecular structures and macroscopic elastic properties in MC-LCEs in general, which should be beneficial for future designs of soft materials with desired shape-memory properties.
Preparation of benzoyloxy benzophenone derivatives and their inhibitory effects of ICAM-1 expression
Kwon, Eun Mi,Kim, Cheol Gi,Goh, Ah Ra,Park, Jinseu,Jun, Jong-Gab
experimental part, p. 1939 - 1944 (2012/08/07)
Benzoyloxy benzophenone derivatives were prepared in 3 steps including DCC coupling, Fries rearrangement and esterification from benzoic acids in 24-89% total yields. Among the prepared 12 benzophenone analogues 1a-1l, the compound 1b having three chloro groups at the para position showed maximum inhibitory effects of ICAM-1 expression but, 1a which have no substituents at all showed no inhibitory activity. This study provides the evidences that benzoyloxy benzophenone derivative, 1b may exert its anti-inflammatory activity by suppressing IFN-γ-induced ICAM-1 expression.
