The Microscopic Structure–Property Relationship of Metal–Organic Polyhedron Nanocomposites

Monodispersed hairy nanocomposites with typical 2 nm (isophthalic acid)₂₄Cu₂₄ metal–organic polyhedra (MOP) as a core protected by 24 polymer chains with controlled narrow molecular weight distribution has been probed by imaging and scattering studies for the heterogeneity of polymers in the nanocomposites and the confinement effect the MOPs imposing on anchored polymers. Typical confined‐extending surrounded by one entanglement area is proposed to describe the physical states of the polymer chains. This model dictates the counterintuitive thermal and rheological properties and prohibited solvent exchange properties of the nanocomposites, whilst those polymer chain states are tunable and deterministic based on their component inputs. From the relationship between the structure and behavior of the MOP nanocomposites, a MOP‐composited thermoplastic elastomer was obtained, providing practical solutions to improve mechanical/rheological performances and processabilities of inorganic MOPs.     

Synthesis of functionalized asymmetric star polymers containing conductive polyacetylene segments by living anionic polymerization

Novel 3-arm ABC, 4-arm ABCD, and 5-arm ABCDE asymmetric star polymers comprising the conductive polyacetylene precursor, poly(4-methylphenyl vinyl sulfoxide) (PMePVSO), and other segments, such as polystyrene, poly(alpha-methylstyrene), poly(4-methoxystyrene), poly(4-trimethylsilylstyrene), and poly(4-methylstyrene), were synthesized by the methodology based on living anionic polymerization using DPE-functionalized polymers. This methodology involves the addition reaction of a DPE-functionalized polymer to a living anionic polymer followed by the living anionic polymerization of MePVSO initiated from the in situ formed polymer anion with two, three, or four polymer segments. The resultant asymmetric star polymers possessed predetermined molecular weights, narrow molecular weight distributions (Mw/Mn < 1.03), and desired compositions as confirmed by SEC, 1H NMR, SLS, and elemental analysis. After thermal treatment, the PMePVSO segment in the star polymer could be completely converted into a conductive polyacetylene segment, evident from TGA and elemental analysis. These asymmetric star polymers are expected to exhibit interesting solution properties and unique microphase-separated morphological suprastructures with potential applications in nanoscopic conductive materials. Moreover, this methodology can afford the target asymmetric star polymers with arm segments varying in a wide range and enables the synthesis of more complex macromolecular architectures.     

Synthesis of 4-arm methyl methacrylate star polymer by atom transfer radical polymerization

The synthesis of 4-arm methyl methacrylate star polymer had been achieved successfully by atom transfer radical polymerization using CuCl as catalyst, 2, 2′-bipyridyl as ligand and pentaerythritol tetrakis (2-bromoisobutyrate) as the initiator. The star polymer was characterized by ¹H-NMR and GPC, by which the precise 4-arm structure of the PMMA was confirmed. __________ Translated from Journal of Shaanxi Normal University (Natural Science Edition), 2008, 36(2) (in Chinese)     

Star PolyMOCs with Diverse Structures,Dynamics, and Functions by Three‐Component Assembly

We report star polymer metal–organic cage (polyMOC) materials whose structures, mechanical properties, functionalities, and dynamics can all be precisely tailored through a simple three‐component assembly strategy. The star polyMOC network is composed of tetra‐arm star polymers functionalized with ligands on the chain ends, small molecule ligands, and palladium ions; polyMOCs are formed via metal–ligand coordination and thermal annealing. The ratio of small molecule ligands to polymer‐bound ligands determines the connectivity of the MOC junctions and the network structure. The use of large M₁₂L₂₄ MOCs enables great flexibility in tuning this ratio, which provides access to a rich spectrum of material properties including tunable moduli and relaxation dynamics.     

Star PolyMOCs with Diverse Structures,Dynamics, and Functions by Three‐Component Assembly

We report star polymer metal–organic cage (polyMOC) materials whose structures, mechanical properties, functionalities, and dynamics can all be precisely tailored through a simple three‐component assembly strategy. The star polyMOC network is composed of tetra‐arm star polymers functionalized with ligands on the chain ends, small molecule ligands, and palladium ions; polyMOCs are formed via metal–ligand coordination and thermal annealing. The ratio of small molecule ligands to polymer‐bound ligands determines the connectivity of the MOC junctions and the network structure. The use of large M₁₂L₂₄ MOCs enables great flexibility in tuning this ratio, which provides access to a rich spectrum of material properties including tunable moduli and relaxation dynamics.     

Methods for the synthesis of uniform polymers

The difficulties encountered in the preparation of polymers that are uniform chemically, structurally, and in their molecular weight are due mainly to the wide variety of possible polymers. This arcticle gives a review of attempts to synthesize homogeneous polymers by chain reactions and by stepwise synthesis. Syntheses on templates are extremely important in living cells; methods have recently been found for syntheses of this type that are independent of natural processes. Uniform polymers can also be obtained by reactions on existing polymers. In replicating polymers, this in principle requires the modification of only one polymer molecule.     

Synthesis of heteroarm star polymers comprising poly(4-methylphenyl vinyl sulfoxide) segment by living anionic polymerization

<正>A series of 3-arm ABC and AA'B and 4-arm ABCD,AA'BC and AA′A″B heteroarm star polymers comprising one poly(4-methylphenyl vinyl sulfoxide) segment and other segments such as polystyrene,poly(α-methylstyrene), poly(4-methoxystyrene) and poly(4-trimethylsilylstyrene) were synthesized by living anionic polymerization based on diphenylethylene(DPE) chemistry.The DPE-functionalized polymers were synthesized by iterative methodology,and the objective star polymers were prepared by two distinct methodologies based on anionic polymerization using DPE-functionalized polymers.The first methodology involves an addition reaction of living anionic polymer with excess DPE-functionalized polymer and a subsequent living anionic polymerization of 4-methylphenyl vinyl sulfoxide(MePVSO) initiated from the in situ formed polymer anion with two or three polymer segments.The second methodology comprises an addition reaction of DPE-functionalized polymer with excess sec-BuLi and a following anionic polymerization of MePVSO initiated from the in situ formed polymer anion and 3-methyl-1,1-diphenylpentyl anion as well.Both approaches could afford the target heteroarm star polymers with predetermined molecular weight,narrow molecular weight distribution (M_w/M_n1.03) and desired composition,evidenced by SEC,~1H-NMR and SLS analyses.These polymers can be used as model polymers to investigate structure-property relationships in heteroarm star polymers.     

Chain-growth polymerization of azide–alkyne difunctional monomer: Synthesis of star polymer with linear polytriazole arms from a core

This article reports a chain-growth coupling polymerization of AB difunctional monomer via copper-catalyzed azide–alkyne cycloaddition (CuAAC) reaction for synthesis of star polymers. Unlike our previously reported CuAAC polymerization of AB _n (n ≥ 2) monomers that spontaneously demonstrated a chain-growth mechanism in synthesis of hyperbranched polymer, the homopolymerization of AB monomer showed a common but less desired step-growth mechanism as the triazole groups aligned in a linear chain could not effectively confine the Cu catalyst in the polymer species. In contrast, the use of polytriazole-based core molecules that contained multiple azido groups successfully switched the polymerization of AB monomers into chain-growth mechanism and produced 3-arm star polymers and multi-arm hyperstar polymers with linear increase of polymer molecular weight with conversion and narrow molecular weight distribution, for example, M_w/M_n ~ 1.05. When acid-degradable hyperbranched polymeric core was used, the obtained hyperstar polymers could be easily degraded under acidic environment, producing linear degraded arms with defined polydispersity. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020 , 58, 84–90     

Synthesis of multidentate functional monomer for ion imprinting

In this work, N,N,N‐tri(2‐carboxyethyl)‐3‐(2‐aminoethylamino)propyl‐trimethoxysilane was prepared as a multidentate functional monomer. The 3D model of the monomer coordinating with Cu²⁺ indicated that the monomer is able to provide five ligating atoms like ethylenediaminetetraacetic acid‐Cu²⁺ to complex with Cu²⁺. When Cu²⁺ was used as a template ion, the synthesis conditions of Cu²⁺‐imprinted polymers were optimized upon orthogonal design. It is interesting to find that Cu²⁺‐imprinted polymer offers a selectivity coefficient of 192.2 when the molar ratio of Cu²⁺ to monomer was exactly 1:1. That means there is no excess ligating atom in the ion‐imprinted polymer and therefore, the nonspecific adsorption could be avoided. Benefiting from the excellent selectivity of Cu²⁺‐imprinted polymer, even if the concentration of Zn²⁺ was 25 times that of Cu²⁺, Cu²⁺‐imprinted polymer still affords a high selectivity coefficient. Finally, the optimal synthesis conditions for Cu²⁺‐imprinted polymer, except the pH, were adopted to prepare Ni²⁺‐imprinted polymer, and Ni²⁺‐imprinted polymer also offered satisfying selectivity to Ni²⁺. That implies this multidentate monomer is adaptable in ion imprinting and, the optimal synthesis conditions of Cu²⁺‐imprinted polymer except pH are likely suitable for the imprinting of other ions besides Cu²⁺.     

Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin-Decorated Cu24L24 Metal–Organic Cages as Junctions

Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre-irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu₂₄L₂₄ metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu^II, Cu^I, and Cu⁰. The instability of the MOC junctions in the Cu^I and Cu⁰ states leads to network disassembly, forming Cu^I/Cu⁰ solutions, respectively, that are stable until re-oxidation to Cu^II and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper-catalyzed azide-alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.     

A New Metalloligand Powerful in Forming Helical Coordination Polymers

A new macrocyclic oxamido carboxylate metalloligand was designed and three heteronuclear coordination polymers of the metalloligand and metal nodes Cu²⁺, Zn²⁺ and Cd²⁺ were prepared. X-ray single crystal analyses (CIF files CCDC nos. 1025722–1025724 for I–III) revealed that multiple favourable features endowed the metalloligand with a strong power to force the metal nodes to generate 1D helical coordination polymers. Thermogravimetric analyses showed that the complexes with Cu²⁺ and Zn²⁺ nodes exhibited moderate thermal stability. The three complexes were also characterized by IR spectra and PXRD.     

Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin‐Decorated Cu24L24 Metal–Organic Cages as Junctions

Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre‐irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu₂₄L₂₄ metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu^II, Cu^I, and Cu⁰. The instability of the MOC junctions in the Cu^I and Cu⁰ states leads to network disassembly, forming Cu^I/Cu⁰ solutions, respectively, that are stable until re‐oxidation to Cu^II and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.     

Solvent‐Annealing‐Induced Nanowetting in Templates: Towards Tailored Polymer Nanostructures

We study the solvent‐annealing‐induced nanowetting in templates using porous anodic aluminum oxide membranes. The morphology of polystyrene and poly(methyl methacrylate) nanostructures can be controlled, depending on whether the swollen polymers are in the partial or complete wetting regimes, which are characterized by the spreading coefficient. When the swollen polymers are in the partial wetting regime, polymers wet the nanopores by capillary action, resulting in the formation of polymer nanorods. When the swollen polymers are in the complete wetting regime, polymers form wetting layers in the nanopores, resulting in the formation of polymer nanotubes. The solubility parameters of polymers and solvents are also used to predict the wetting behavior of swollen polymers in cylindrical geometry.     

Dynamics of star branched polymers in a matrix of linear chains — a Monte Carlo study

A simple cubic lattice model of the melt of 3-arm star-branched polymers of various length dissolved in a matrix of long linear chains (n₁ = 800 beads) is studied using a dynamic Monte Carlo method. The total polymer volume fraction is equal to 0,5, while the volume fraction of the star polymers is about ten times smaller. The static and dynamic properties of these systems are compared with the corresponding model systems of isolated star-branched polymers and with the melt of linear chains. It has been found that the number of dynamic entanglements for the star polymers with arm length up to 400 segments is too small for the onset of the arm retraction mechanism of polymer relaxation. In this regime dynamics of star-branched polymers is close to the dynamics of linear polymers at corresponding concentration and with equivalent chain length. The entanglement length for star polymers appears to be somewhat larger compared with linear chains.     

Conjugated Nanohoop Polymers based on Antiaromatic Dibenzopentalenes for Charge Storage in Organic Batteries

With their bent π-systems, cyclic conjugation and inherent cavities, conjugated nanohoops are attractive for organic electronics applications. For ease of processing and morphological stability, an incorporation into polymers is desirable, but to date was hampered with few exceptions by synthetic difficulties. We herein present a unique strategy for the synthesis of conjugated nanohoop polymers using a dibenzo[a,e]pentalene (DBP) as central connector. We demonstrate this versatility by synthesizing three electronically diverse copolymers with dithienyldiketo(pyrrolopyrrol), fluorene and carbazole comonomers, and report the first donor-acceptor nanohoop polymer. Optoelectronic investigations reveal the prevalence of cyclic or linear conjugation, depending on the comonomer unit, and ambipolar electrochemical properties through the antiaromatic character of the DBP units. As the first report on using conjugated nanohoops for charge storage as positive electrode materials, we show a significant improvement in battery performance in a nanohoop-containing polymer compared to an equivalent nanohoop-free reference polymer. We believe this study will pave the way for the synthesis of a diverse range of nanohoop polymers and further stimulate their exploration for charge storage in batteries.     

Co-ordination polymers of bis(8-hydroxy-5-quinolylmethylene) sulphide (BHQS)

Co-ordination polymers of bis(8-hydroxy-5-quinolylmethylene)sulphide have been prepared with Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺ and Mn²⁺ ions and characterized by elemental analyses, by i.r. and diffuse reflectance spectral studies and by magnetic moment. The metal contents in all polymers are found to be consistent with 1:1 (metal:ligand) stoichiometry. The thermal behaviour of each of the co-ordination polymer has been studied by TGA in air up to 700°C.     

Supramolecular structures based on dimeric combinations of cyclodextrin and adamantane via click chemistry

The cyclic starches α-, β-, and γ-cyclodextrins (CDs) readily form inclusion complexes (ICs) with a large variety of polymers. In polymer-CD-ICs, the CD hosts are threaded by the guest polymers, which must be highly extended, and stacks of polymer threaded host CDs pack closely together and crystallize. When guest polymers are coalesced from their CD-IC crystals, by washing with a solvent good, bad for CD, polymer, or treatment with an amylase enzyme, the guest polymers coalesce into bulk samples whose structures, morphologies, and even conformations are distinct from bulk samples made from their solutions and melts. We generally observe (i) crystallizable homopolymers coalesced from their CD-ICs to evidence increased levels of crystallinity, unusual polymorphs, and higher melting, crystallization, and decomposition temperatures, while coalesced amorphous homopolymers exhibit higher glass-transition temperatures, than samples consolidated from their disordered solutions and melts; (ii) molecularly mixed, intimate blends of two or more polymers that are normally believed to be immiscible can be achieved by coalescence from their common CD-IC crystals, (iii) the phase segregation of incompatible blocks can be controlled (suppressed or increased) when block copolymers are coalesced from their CD-IC crystals, and (iv) the thermal and temporal stabilities of the coalesced and well-mixed homopolymer blends and block copolymers appear to be substantial, thereby suggesting retention of as-coalesced structures and morphologies under normal thermal processing conditions. Furthermore, CDs may be covalently incorporated in polymers both during and after their syntheses, thereby providing a broad range of new functionalities for delivery of additives or to act as sensors or filters. Alternatively, additive-CD-ICs or additives rotaxanated with CDs may be effectively delivered to polymers. As an example, TiO₂—filled polypropylene fibers may be readily dyed in aqueous solution using water soluble CD-rotaxanated azo-dyes.     

Cu2+-complexes of polyamino acids in aqueous solutions catalytic activity (H202-decomposition) and structure

The decomposition of H₂O₂ (8 · 10^?3M ) catalyzed by complexes of Cu²⁺ (4 · 10^?4M ) with various oligomers and polymers of glycine, L-lysine or L-glutamic acid was investigated in aqueous solution in the pH range 5–11, at 24°C and at low ionic strength. Previous investigations have shown that the decomposition of H₂O₂ is catalyzed by Cu²⁺-complexes capable of forming Cu²⁺-peroxocomplexes. With increasing pH the catalytic activity of Cu²⁺-complexes with glycine or glycylglycine (1:1) increases while the activity of Cu²⁺-complexes with tri- or tetraglycine (1:1) is comparatively small at higher pH values apparently because in the latter cases the coordination positions of the copper become progressively occupied by the peptides. This interpretation is in accordance with the pH-dependence of the light-absorption spectra of the latter complexes. Cu²⁺-complexes with poly-α, L -lysines of various molecular weights (molar ratios Cu²⁺: lysine residues = 1:15) have a catalytic activity comparable to or higher than that of the complex Cu²⁺-ethylenediamine (1:1), indicating two available coordination positions for formation of peroxo-complexes. On the other hand, the system Cu²⁺-L -lysine (1:15) showed no significant activity probably because all coordination positions at the Cu²⁺ are occupied by lysine. Despite the excess of ligand groups over Cu²⁺ in the polylysine systems the structure of this polyamino acid apparently does not allow its full coordination with these groups under the conditions investigated. Two adjacent chelating ε-amino groups are considered as the main ligand groups of the polymer to each copper ion. The Cu²⁺-poly-α, L -glutamic acid complex examined (Cu²⁺: glutamic acid residues = 1:5) shows comparatively little activity. In this case, absorption spectra indicate formation of hydroxo-complexes at higher pH. Besides the effects of structure, the electrostatic fields of the charged polyelectrolytes polylysine or polyglutamic acid are also considered to affect the rates of catalysis.     

Heterometallic iodoplumbates modified by copper(I) or silver(I) with viologens

Cu/Ag(I) were introduced into iodoplumbate systems to produce two new heterometallic iodoplumbates with viologen as templates, i.e. (PV)₂(Pb₂Cu₂I₁₀) (1) and [(BV)(Pb₂AgI₇)]_n (2) (PV²⁺ = propyl viologen, BV²⁺ = benzyl viologen), in which the common connection of PbI₆ units have been remarkably altered. In (PV)₂(Pb₂Cu₂I₁₀) (1), two PbI₆ octahedra are bridged by two CuI₄ tetrahedra via face-sharing to give a (Pb₂Cu₂I₁₀)^4? cluster, but the ternary one-dimensional polymeric (Pb₂AgI₇)_n^2n? of [(BV)(Pb₂AgI₇)]_n (2) is assembled from edge-sharing AgI₄ tetrahedra and PbI₆ octahedra. Their optical band gaps and fluorescence were also discussed. The absorption edges of haloplumbates could be engineered by introduction of suitable conjugated molecules as templates.     

Two zinc (II) coordination polymers based on aliphatic ether Schiff base: Synthesis,crystal structure,antioxidation and fluorescence

The synthesis of two 1D coordination polymers [Zn₂L¹₂]_n 1 and [Zn₂L²₂]_n 2 , based on the H₂L¹ (bis (salicylidene)‐3‐oxapentane‐1,5‐diamine) and the H₂L² (bis (5‐methylsalicylaldehyde)‐3‐oxapentane‐1,5‐diamine) ligands, have been described and characterized by IR, elemental analysis and X‐ray single crystal analyses. In coordination polymer 1 , each Zn²⁺ ion is five‐coordinated by three oxygen atoms and two nitrogen atoms from deprotonated ligand forming a square pyramidal configuration. It is worth noting that phenolic oxygens of the deprotonated H₂L¹ adapt monodentate and monoatomic bridging coordinated modes resulting in one‐dimensional linear chain structure in which macro rings alternately connect small rings. The coordination polymer 2 is a four‐coordinated one‐dimensional zigzag chain in which geometric structure around the Zn (II) atom can be described as distorted tetrahedron. The antioxidant activity of the coordination polymers 1 – 2 and the ligands were determined by superoxide and hydroxyl radical scavenging method in vitro. The results demonstrated that the coordination polymers exhibit more effective antioxidant activity than the ligands. Moreover, compared with emissive bands of the free ligands in the solid state and DMF solvent, the photoluminescent transition of the Zn (II) coordination polymer 1 – 2 may be attributed to ligand‐to‐ligand charge‐transfer regulated by Zn (II) ion.