Literatura científica selecionada sobre o tema "Coassemblies"

Dynamic evolution of supramolecular chirality inversion and the inversion of corresponding circularly polarized luminescence via the multiple-constituent coassemblies driven by hydrogen bonds was realized.

Coassemblies of chiral cationic block polymers and achiral anionic Eu-POMs through electrostatic interactions display salt-responsive induced circularly polarized luminescence, which arises from the static coupling and dynamic coupling.

La nucléation des polymères semi-cristallins, et en particulier du polypropylène, est une stratégie industrielle efficace pour contrôler les propriétés thermiques, mécaniques et optiques et pour raccourcir le cycle de compoundage. La conception des agents de nucléation reste essentielle pour l'industrie afin d'obtenir les propriétés souhaitées, telles que la ténacité et la clarté optique. Les agents de nucléation les plus rentables sont des molécules organiques de faible poids moléculaire qui forment des auto-assemblages supramoléculaires dans le polymère fondu, ce qui fournit une surface hétérogène favorable à la cristallisation épitaxique du polymère. Néanmoins, la conception d'agents de nucléation est largement basée sur des relations empiriques. Dans cette étude, nous avons cherché à combler cette lacune en explorant les coassemblages de ces derniers. Nous avons développé une méthodologie d'analyse complète permettant une compréhension approfondie des systèmes supramoléculaires dans les milieux polymères fondus. À cette fin, deux agents de nucléation ont été sélectionnés sur la base de leur sélectivité pour différents morphismes de PP. Leur assemblage et leur structure ont été analysés par des méthodes spectroscopiques, microscopiques, calorimétriques et de diffraction des rayons X. Nous avons ensuite étudié la formation de leur co-assemblages en utilisant le même ensemble de techniques. L'ajustement et la modélisation des mesures expérimentales acquises à l'équilibre thermodynamique nous ont permis d'accéder aux paramètres thermodynamiques de notre système, ce qui nous a permis de comprendre la nature des hétéro-interactions au niveau moléculaire. Cette étude théorique a permis de mettre en évidence la microstructure des copolymères obtenus. Nous avons utilisé cette information pour rationaliser la relation structure-propriétés entre la structure de l'agent de nucléation et la cristallinité du polypropylène. Enfin, inspirés par cette approche, nous avons commencé à concevoir et à préparer un nouveau système modèle qui nous permettrait de comprendre ces processus d'auto-assemblage aux interfaces polymère-polymère
Nucleation of semi-crystalline polymers, and in particular polypropylene, is an effective industrial strategy to control thermal, mechanical and optical properties and to shorten the compounding cycle. The design of nucleating agents remains industrially key to achieve desirable properties, such as toughness and optical clarity. The most cost-effective nucleating agents are low molecular weight organic molecules that form supramolecular self-assemblies in the polymer melt, which provide a heterogeneous surface that is favorable for the polymer to undergo epitaxial crystallization. Nevertheless, the design of nucleating agents is largely based on empirical relationships. In this study, we aimed to address this gap by exploring coassemblies of nucleating agents. We developed a complete methodology of analysis allowing a deep understanding of supramolecular systems in molten polymeric media. For this purpose, two nucleating agents were selected on the basis of their selectivity for different PP morphisms. Their assembly and structure were analyzed by spectrocopic, microscopic, calorimetric, and X-ray diffraction methods. We then proceeded to study the formation of the coassembled nucleating agents using the same set of techniques. Fitting and modeling of experimental measurements acquired at thermodynamic equilibrium allowed us to access the thermodynamic parameters of our system, which ultimately gave us insight into the nature of the hetero-interactions at a molecular level. This theoretical study revealed the microstructure of the obtained copolymers. We used this information to rationalize the structure-properties relationship of between nucleating agent structure and polypropylene crystallinity. Finally, inspired by this approach, we began to design and prepare a new model system that would allow us to understand these self-assembly processes at polymer-polymer interfaces

Most low molecular weight (LMW) hydrogels reported to date are based on a single component, which often restricts their functionality. Development of multicomponent gels (MCGs) is an emerging field in the current research because it can expand the functionality of the gels through the improvement or even introduction of properties and functionalities by the synergistic effect of individual components. Herein, LMW MCGs are discussed in terms of their formation through various noncovalent interactions, alteration/incorporation of the properties and functionality of the gels. An MCG literally means a gel containing more than one component; however, herein two-component gels have been mostly discussed as they are the most common representative of MCGs. These two-component gels can be formulated as A + B = MCG (where A/B = gel/sol), which offers three different possibilities in terms of the gelation ability of the individual components. In an MCG, molecular components can be coassembled together, producing a coassembled gel containing a single type of gel fiber, or they can be self-assembled individually, resulting in a system containing different kinds of fibers, called a self-sorted gel. Although two-component gels are the most common, a system with multi-functionalities demands development of MCGs with more than two components.