Design of Heterocomplementary H‐Bonding RAFT Agents – Towards the Generation of Supramolecular Star Polymers

Supramolecular poly(vinyl acetate) PVAc 3‐arms stars were successfully generated by Reversible Addition–Fragmentation chain Transfer (RAFT)‐polymerized chains bearing hydrogen‐bonding heterocomplementary associating units. Chain Transfer Agents (CTA) bearing thymine‐ and diaminopyridine‐based units were first synthesized and proved to mediate efficiently the polymerization of VAc. The binding ability of the chains in solution was then demonstrated by ¹H NMR and GPC measurements, proving the formation of the supramolecular stars.

     

Supramolecular Nanocycles Comprising β‐Cyclodextrin‐click‐Ferrocene Units: Rings of Rings of Rings

We applied 1,3‐dipolar cycloaddition to bind ethynylferrocene onto 6I‐azido‐6I‐deoxycyclomaltoheptaose under microwave assisted conditions. The process was investigated by ¹H NMR, FT‐IR spectroscopy, and MALDI‐TOF mass spectrometry. The ability of the synthesized compound to self‐organize to cyclic supramolecular structures was investigated by dynamic light scattering measurements and cryo‐transmission electron microscopy.

     

Large‐Scale Production of Homogeneous Helical Amylose/SWNTs Complexes with Good Biocompatibility

The key to developing novel applications of SWNTs in biotechnology and biomedicine is to improve their biocompatibility and solubility in water and to assemble them into useful architectures. We describe how amylose can help to solubilize SWNTs and wrap around SWNTs into helical superstructures with periodic pitch. FT‐IR, Raman spectroscopy, ¹H NMR and HR‐TEM are used to confirm the generation of amylose/SWNTs complexes (A/S‐C). It is demonstrated that most of the A/S‐C have similar diameters (ca. 20–30 nm) and a helical morphology with a pitch of ca. 14 nm. A test of Hela cell viability revealed that the A/S‐C had much better biocompatibility than SWNTs.

     

Oriented Synthesis of One‐Dimensional Polypyrrole Molecule Chains in a Metal‐Organic Framework

We report for the first time the preparation of single polypyrrole (PPy) molecule chains using a “metal‐organic framework” with 1 nm channels as a template. The obtained one‐dimensional (1‐D) PPy has highly structure order and excellent conductivity, which has improved by as much as five orders of magnitude in comparison with that of 2‐D PPy.

     

Metallo‐Supramolecular Diethylene Glycol: Water‐Soluble Reversible Polymers

Bis(2,2′:6′,2″‐terpyrid‐4′‐yl) diethylene glycol was synthesized as a monomer unit and further utilized for polymerization with FeCl₂ in order to form water‐soluble coordination polymers. Viscosity measurements and film‐forming properties indicate the formation of linear coordination polymers or larger ring structures. The terpyridine/iron(II) complexes are stable up to temperatures of 210 °C, but can be uncomplexed by the addition of an excess of a strong competitive ligand (HEDTA) under mild conditions.

     

Synthesis and Properties of Oligophenylene‐Layered Polymers

We report syntheses of phenylene‐, biphenylene‐, and terphenylene‐layered polymers with a xanthene scaffold by the modified Suzuki‐Miyaura coupling reaction. Their optical properties were studied in detail. The polymer end‐capped by nitrobenzene units, which act as fluorescence quenchers, exhibited the photo‐excited energy transfer from the layered oligophenylenes to the terminal units.

     

Crosslinkable Vesicles Self‐Assembled by Amphiphilic Hyperbranched Polyester

Summary: Amphiphilic hyperbranched polyester (H20‐AM) with methacrylate end groups was synthesized based on hyperbranched aliphatic polyester (Boltorn™ H20). Narrow‐dispersed crosslinkable vesicles were obtained by dissolving H20‐AM in water, and characterized by laser light scattering and TEM. The hollow structural vesicle is composed of around 350 H20‐AM molecules, having a radius of around 40 nm and of 1.9 × 10⁶ g · mL⁻¹. The vesicles were fixed by crosslinking of methacrylate groups to form shape‐persistent structures.

TEM images of the crosslinked vesicles at lower magnification.     

Synthesis of Multiblock Polymer Containing Narrow Polydispersity Blocks

Summary: We have developed a new strategy to prepare multiblock polymers and copolymers via one‐ or two‐step polymerization using a polymerizable cyclic trithiocarbonate (CTTC), 4,7‐diphenyl‐[1,3]dithiepane‐2‐thione. CTTC undergoes ring‐opening process to incorporate a trithiocarbonate moiety. The trithiocarbonate moiety in turn, functions as a reversible addition fragmentation chain transfer (RAFT) agent. Through this mechanism, multiblock polystyrenes and polystyrene‐block‐ poly(butyl acrylate) copolymers containing various narrow polydispersity blocks can be prepared.

Integrated process of ring‐opening and RAFT polymerizations involving cyclic trithiocarbonates.     

Novel Acid‐Labile,Thermoresponsive Poly(methacrylamide)s with Pendent Ortho Ester Moieties

Novel acid‐labile, thermoresponsive methacrylamide‐based (co)polymers with pendent ortho ester groups were prepared by free radical polymerization of N‐(2‐methoxy‐1,3‐dioxan‐5‐yl) methacrylamide (NMM) and N‐(2‐ethoxy‐1,3‐dioxan‐5‐yl)methacrylamide (NEM). These polymers are both thermoresponsive and acid‐sensitive in aqueous solution, which was proved by transmittance measurements, fluorescence, and ¹H NMR spectroscopy. The LCSTs of the (co)polymers were shifted to higher temperature by increasing the content of the more hydrophilic NMM units. All of these polymers can be hydrolyzed under acidic condition and the hydrolysis rate increased with the decrease in the pH value.

     

Construction of a Hexameric Zn(II)‐metallomacrocycle and its Photo‐ and Electroluminescence Properties: [Zn6(O‐hexyl‐3,5‐bis(2,2′:6′,2″‐terpyridine)phenol)6(BF4)12]

Summary: An O‐hexyl‐3,5‐bis(terpyridine)phenol ligand has been synthesized and transformed into a hexagonal Zn(II)‐metallomacrocycle by a facile self‐assembly procedure capitalizing on terpyridine‐Zn(II)‐terpyridine connectivity. The structural composition was confirmed by NMR and mass spectral techniques; photo‐ and electroluminescence properties were also investigated. The OLED device shows green electroluminescent emission at 515 nm with a maximum luminance of 39 cd · m⁻² and maximum efficiency of 0.16 cd · A⁻¹.

Structure and electroluminescent properties of the metallomacrocycle investigated.     

Influence of Crystal Thickness and Topological Constraints on Chain Diffusion in Linear Polyethylene

¹³C solid‐state exchange NMR is applied to study the influence of morphology on chain diffusion between crystalline and noncrystalline regions in ultrahigh molecular weight linear polyethylene (PE). Lamellar‐doubling reduces the exchange rate by a factor of two indicating that the chain diffusion coefficient is largely independent of the lamellar thickness. This is discussed in terms of molecular processes in the crystallites leading to chain diffusion, confirming that the role of defects is minor compared to helical jumps of extended stems. Hindrance of the chain diffusion resulting from chain entanglements was only observed after the chains diffuse over long distances. Moreover, the role of the interphase between the noncrystalline and the crystalline regions on chain diffusion is discussed.

     

A Rapid Eco‐Friendly Synthesis of Poly(butylene succinate) by a Direct Polyesterification under Microwave Irradiation

Summary: A rapid and eco‐friendly synthesis of poly(butylene succinate) (PBS) using microwaves was developed in the presence of 1,3‐dichloro‐1,1,3,3‐tetrabutyldistannoxane as catalyst. To determine the optimum conditions, the effect of catalyst concentration, bulk vs. solution polymerization, reaction time, temperature, and stoichiometry of the monomers were studied. Based on the optimum conditions, PBS with a weight‐average molecular weight of 2.35 × 10⁴ was obtained in a short time of 20 min.

Synthesis of poly(butylene succinate) under microwave irradiation.     

Synthesis,Microstructure, and Acidity of Poly(vinylphosphonic acid)

Summary: Vinylphosphonic acid is polymerized at 80 °C by free radical polymerization to give a high‐molecular‐weight polymer ( of 6.2 × 10⁴) as determined by static light scattering. High‐resolution NMR spectroscopy is used to gain microstructure information. Information based on tetrad probabilities is utilized to deduce an almost atactic configuration. In addition, ¹³C NMR spectroscopy gives evidence for the presence of head‐to‐head and tail‐to‐tail links. Refined analysis of the ¹H NMR spectra allows for the quantitative determination of the fraction of these links (23.5% of all links). Experimental evidence suggests that the polymerization proceeds via cyclopolymerization of the vinylphosphonic acid anhydride as an intermediate. Titration curves indicate that high‐molecular‐weight poly(vinylphosphonic acid) PVPA behaves as a monoprotic acid.

Radical polymerization of vinylphosphonic acid proceeds by cyclopolymerization of its anhydride.     

A Composite Polymer Film with both Superhydrophobicity and Superoleophilicity

Summary: A composite film composed of porous polyurethane (PU) and polystyrene (PS) microspheres with both superhydrophobicity and superoleophilicity has been prepared. In this film, the dual‐scale structure enhances both the hydrophobicity and oleophilicity of the surface material. The composite film with such an ‘intelligent’ wettability property can be utilized to separate oil and water systems efficiently.

The composite film can be used to separate diesel oil and water.     

Synthesis and Characterization of a Novel Degradable Aliphatic Polyester that Contains Monomeric Lactate Sequences

Summary: A novel degradable aliphatic polyester that contains monomeric lactate sequences is synthesized via melt‐polycondensation of ethylene glycol lactate diol (EGLD) with succinic anhydride without the use of catalyst. The structure of the EGLD precursor and the polyester are verified with FT‐IR and ¹H NMR spectra. Gel permeation chromatography reveals that the weight‐average molecular weight of the polyester is 5.5 × 10⁴ with a polydispersity index (PDI) of 1.7. Differential scanning calorimetry profiles reveal that the polyester is a semicrystalline polymer with a glass transition temperature of −12 °C and melting temperature of 101 °C. The weight loss percentage of the polyester after immersing for 208 d in active sludge is 2.7%, which suggests degradation has occurred.

The synthesis route of the polyester synthesized here (see inset for structure).     

Chemoenzymatic Synthesis of Amylose‐Grafted Chitosan

An amylose‐grafted chitosan has been synthesized by a chemoenzymatic method according to the following two reactions. First, maltoheptaose is introduced to chitosan by a reductive amination using sodium cyanotrihydroborate in a mixed solvent of 1.0 mol · L⁻¹ aqueous acetic acid and methanol at room temperature to produce a maltoheptaose‐grafted chitosan that has a well‐defined molecular structure. A phosphorylase‐catalyzed enzymatic polymerization of α‐D ‐glucose 1‐phosphate is then performed from the maltoheptaose‐grafted chitosan to obtain the amylose‐grafted chitosan. This material does not dissolve in any solvent, e.g., aqueous acetic acid and dimethyl sufoxide, which are good solvents for chitosan and amylose, respectively.

     

An Efficient and Environmentally Friendly Method for the Synthesis of Cellulose Carbamate by Microwave Heating

An efficient, solvent‐free, and catalyst‐free microwave synthesis of cellulose carbamate from a mixture of native cellulose and urea is reported. The structure of the samples are characterized by elemental analysis, FT‐IR spectroscopy, X‐ray diffraction, and NMR spectrometry. Cellulose carbamates with a nitrogen content of 0.651–2.427% are obtained by microwave heating at 255 W for 2–5 min. With the introduction of carbamate groups, the hydrogen bonding and crystalline structure of the native cellulose are partially destroyed. The products retain the cellulose I crystalline form of the native cellulose, and display good solubility in NaOH solutions.

     

Recyclable Spherical Polyelectrolyte Brushes Containing Magnetic Nanoparticles in Core

Spherical polyelectrolyte brushes consisting of a magnetite/polystyrene nanocomposite core and a poly(acrylic acid) brush shell were prepared by photo‐emulsion polymerization. They are narrowly dispersed, superparamagnetic and redispersible after aggregating by external magnetic field, as determined by transmission electron microscopy, dynamic light scattering, thermal gravimetric analysis and a vibrating sample magnetometer. Magnetic control is thus introduced into nano‐sized spherical polyelectrolyte brushes to achieve recovery and controllable delivery in applications. This approach opens up the way for cost‐effective applications of spherical polyelectrolyte brushes.

     

Novel Chromophore‐Functionalized Poly[2‐(trifluoromethyl) adamantyl acrylate‐methyl vinyl urethane]s with High Poling Stabilities of the Nonlinear Optical Effect

Nonlinear optical vinyl polymers with high glass transition temperature (T_g) were prepared by the functionalization of a fluorinated acrylate‐methyl vinyl isocyanate copolymer. A modified pathway to obtain a thiophene bridged chromophore was worked out. Poled films of the polymers show a fairly high and stable nonlinear optical response, even at elevated temperatures.

The thiophene‐bridged chromophore, based on a substituted dicyanomethylene‐dihydrofuran acceptor, synthesized here.