Morphosynthesis strategies inspired by biomineralization processes gives access to a wide range of fascinating and useful crystalline mesostructures. Biomimetic synthesis of inorganic materials with complex shapes can now be used to control the nucleation, tensorial growth, and alignment of inorganic crystals in a way previously not practicable. Double hydrophilic block copolymers (DHBCs) consisting of a hydrophilic block strongly interacting with inorganic minerals, and a non-interacting hydrophilic block, were recently introduced for the control of mineralization reactions. DHBCs are 'improved versions' of the previously used polyelectrolytes or amphiphiles and are extraordinarily effective in crystallization control. Here, we report on the formation of helices of achiral BaCO(3) nanocrystals in the presence of a racemic DHBC suggesting that a helical alignment can be induced by racemic polymers through selective adsorption on the (110) face of nanocrystals. This mechanism is the key for a better understanding of the self-assembly of chiral organic-inorganic superstructures that don't follow a direct template route.
A facile and sustainable synthesis of hollow carbonaceous nanospheres is presented, offering a scalable and multifunctional route to the generation of useful nanocontainers, which critically possess the stability not offered by polymeric equivalents and functionality not afforded by other nanocarbons. Carbonization temperature provides a subtle but elegant mechanism to control structure and thereby hydrophobicity, nanopartitioning, and permeation between the inner and outer space.
Thermosensitive hollow capsules were successfully fabricated by the layer‐by‐layer deposition onto colloid particles of oppositely charged diblock copolymers each containing a poly(N‐isoproprylacrylamide) (PNIPAM) block and by the subsequent decomposition of the core. The multilayer growth was characterized by electrophoresis and single particle light scattering. By combining confocal microscopy observation and FRAP measurements, we showed that the morphology and the permeability of the capsules change upon heating in aqueous solution. The decrease of size accompanied by a decrease of the permeability with increasing temperature was attributed to structural rearrangements in the shell. However, this process is only partially reversible upon cooling, limiting the thermoresponsive behavior of the capsules.CLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).magnified imageCLSM images of hollow capsules in presence of 6‐carboxyfluorescein (left) and fluorescein‐labeled dextran (right).
Many organisms make use of calcium carbonate as a construction material, and for this purpose are able to selectively control the formation of the different polymorphs of this material. This is not the case for technical processes. Calcite is thermodynamically more stable at ambient pressure and temperature [1] than the other anhydrous CaCO 3 polymorphs (vaterite and aragonite), and thus is most easily obtained with long reaction times. There are some technical procedures which generate vaterite (usually the first polymorph formed as a result of the Ostwald rule of stages) by performing the precipitation along the kinetic pathway and yielding the kinetic metastable vaterite product or by trapping and stabilizing the very early crystals [2] with appropriate stabilizers. However, the mechanically very interesting aragonite (usually a high-pressure modification) is virtually inaccessible by chemical means, except by adding extreme amounts of Mg 2+ ions to the mother liquor. [3,4] It should be recalled that nacre, with its extraordinary mechanical performance, is based on pure aragonite platelets [5] and shows clear long-time stability even in the presence of water. In contrast, aragonite usually starts to transform to calcite within a day or faster depending on the pH value and temperature. [6,7] Thus, one of the main challenges in the crystallization of calcium carbonate remains the synthesis of pure aragonite of uniform size and morphology under ambient conditions. It has previously been described that aragonite is formed in a biomimetic pathway in the presence of several extracted
π-Conjugated microporous polyHIPEs are synthesized via Suzuki cross-coupling. The polymeric backbone consists of electron donor and acceptor moieties with suitable energetic characteristics to promote the efficient photosensitizing ability for the activation of singlet oxygen, showing extraordinarily high stability. The reaction can be carried out in a continuous flow reaction set-up, realizing complete conversion of α-terpinene into ascaridole.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.