Search results for "Supramolecular"
showing 10 items of 830 documents
Dynamics of entangled supramolecular polymer networks in presence of high-order associations of strong hydrogen bonding groups
2017
Dynamics of entangled polymer chains in the melt state are deliberately excluded in most of the studies on supramolecular polymer networks by utilizing nonentangled precursor chains. Relaxation of the system mainly depends on the dissociation of the associative groups in latter case and nonentangled chains deliver nothing to resist afterward. Conversely, in an entangled system, relaxation of polymer chains and dissociation of associative groups can occurred parallel. Supramolecular networks based on an entangled precursor polymer with different levels of strong associating ureidopyrimidinone (UPy) groups are synthesized to screen the corresponding effects on the dynamics of the system. Bina…
Molecular Mobility in Oriented and Unoriented Membranes Based on Poly[2-(Aziridin-1-yl)ethanol]
2021
Unoriented and oriented membranes based on dendronized polymers and copolymers obtained by chemical modification of poly[2-(aziridin-1-yl) ethanol] (PAZE) with the dendron 3,4,5-tris[4-(n-dodecan-1-yloxy)benzyloxy]benzoate were considered. DSC, XRD, CP-MAS NMR and DETA, contribute to characterize the tendency to crystallize, the molecular mobility of the benzyloxy substituent, the dendritic liquid crystalline group and the clearing transition. The orientation of the mesogenic chain somewhat hindered this molecular motion, especially in the full substituted PAZE. The fragility, free volume and thermal expansion coefficients of these membranes near the glass transition are related to the orie…
Linear–dendritic block copolymers: The state of the art and exciting perspectives
2011
Concurrent with the rapid development of both dendrimers and hyperbranched polymers, a novel class of block copolymer architectures has emerged from the combination of these dendritic architectures with linear chains, the “linear–dendritic block copolymers” (LDBCs). This review gives a comprehensive summary of the state of the art in this rapidly developing field from pioneering early work to promising recent approaches.The different strategies leading to these hybrid architectures with either perfect dendrimer/dendron building blocks or imperfect, yet more conveniently accessible hyperbranched segments, are reviewed and compared. The consequences of the unusual polymer topology for supramo…
Controlling supramolecular polymerization through multicomponent self-assembly
2016
The self-assembly into supramolecular polymers is a process driven by reversible non-covalent interactions between monomers, and gives access to materials applications incorporating mechanical, biological, optical or electronic functionalities. Compared to the achievements in precision polymer synthesis via living and controlled covalent polymerization processes, supramolecular chemists have only just learned how to developed strategies that allow similar control over polymer length, (co)monomer sequence and morphology (random, alternating or blocked ordering). This highlight article discusses the unique opportunities that arise when coassembling multicomponent supramolecular polymers, and …
An Improved Rapid Synthesis of Oligo(p -benzamide) Block Copolymers
2008
We describe a new synthesis that allows the preparation of oligo(p-benzamide)s up to the heptamer on solid support without the need of semi-temporary amide N-protective groups. With increase in length, the solubility of oligo(p-benzamide)s reduces dramatically. Even the tetra(p-benzamide) is not soluble in common organic solvents. Therefore, solution syntheses of oligomers beyond the tetramer are not feasible. As will be shown in this paper, solid supported synthesis allows the preparation of even longer oligomers (up to the heptamer) in good yields. The high dilution on the solid support is most likely responsible for their pseudo-solution-like reactivity and the prevention of aggregation.…
Dynamics of supramolecular associative polymer networks at the interplay of chain entanglement, transient chain association, and chain‐sticker cluste…
2019
The dynamic mechanical properties of supramolecular associative polymer networks depend on the average number of entanglements along the network‐forming chains, Nₑ, and on their content of associative groups, f. In addition, there may be further influence by aggregation of the associative groups into clusters, which, in turn, is influenced by the chemical structure of these groups, and again by Nₑ and f of the polymer. Therefore, the effects of these parameters are interdependent. To conceptually understand this interdependency, we study model networks in which (a) Nₑ, (b) f, and (c) the chemical structure of the associative groups are varied systematically. Each network is probed by rheolo…
Thermal and viscoelastic properties of entangled supramolecular polymer networks as a powerful tool for prediction of their microstructure
2018
Abstract Thermal and viscoelastic properties of entangled supramolecular polymer networks, SPNs, depend strongly on binary and collective assembly of associative groups. The collective assemblies can phase separate from polymer matrix chains and form domains with different sizes and shapes, which have different melting point transitions. By increasing content of associative groups along the polymer chains, their high-order association leads to formation of domains, which have higher melting temperatures than other ones. We prepared a SPN system that contains three networks. All networks have similar precursor polymer backbone, but different content of ureidopyrimidinone, UPy, moiety as stro…
Colloidal stability and self-assembling behavior of nanoclays
2020
Abstract Currently, nanoclays are attracting the attention of a wide part of the scientific community, due to some of their most peculiar features that make them good candidates for applications in different fields. In light of this, some strategies can be pursued in order to obtain stable colloidal dispersions of nanoclays with the aim to improve their features and to expand their use. Hence, this chapter presents an overview on the structural and morphological characteristics, the physico-chemical properties and the main approaches that are taken into account for the preparation of homogeneous suspensions of Halloysite, Imogolite and Laponite in both aqueous and apolar solvent media. In p…
Supramolecular isomerism in spin crossover networks with aurophilic interactions
2004
Assembly of FeII, 3-cyanopyridine and [Au(CN)2]– affords, in one-pot reaction, three coordination polymers that represent a genuine example of supramolecular isomerism with strong influence in the spin crossover regime of the FeII ions. Real Cabezos, Jose Antonio, Jose.A.Real@uv.es
Electrical conductive coordination polymers
2011
Coordination polymers are currently one of the hottest topics in Inorganic and Supramolecular Chemistry. This critical review summarizes the current state-of-the-art on electrical conductive coordination polymers (CPs), also named metal-organic frameworks (MOFs). The data were collected following two sort criteria of the CPs structure: dimensionality and bridging ligands (151 references).