Supramolecular Assembly of Gold Nanoparticles Mediated by Polypseudorotaxane with Thiolated β‐Cyclodextrin

Summary: A water‐soluble gold nanoparticle aggregate 2 was prepared by chloroauric acid and a polypseudorotaxane 1 of mono‐6‐thio‐β‐cyclodextrin with poly(propylene glycol) bis(2‐aminopropyl ether) ( ≈ 2 000) in the presence of sodium borohydride in N,N‐dimethylformamide (DMF) solution. The investigative results indicated that the gold nanoparticle aggregate 2 might act as an efficient DNA‐cleavage reagent.

A typical TEM image of gold nanoparticle aggregate 2 .     

Contractive Polymeric Complex Micelles as Thermo‐Sensitive Nanopumps

Complex micelles were obtained from PS‐b‐PNIPAM‐b‐PAA micelles and PEG‐b‐P4VP block copolymers via the strong electrostatic interaction and hydrogen bonding between PAA and P4VP blocks in water. The PS block formed the core and the PAA/P4VP complex shell functioned as a semi‐permeable membrane which could control the permeation of small molecules. Between the core and shell, the large fluid‐filled space that was formed with the thermoresponsive PNIPAM gel could retain the loaded drug for a long period of time. With increasing temperature, the shrinkage of the PNIPAM coils pumped the drug out of the complex micelles. The complex micelles functioned as a contractive “nanopump”, which could potentially be applied as a thermosensitive controlled release system.

     

Blue‐Light‐Emitting Conjugated Polymers Derived From 2,7‐Carbazoles

Blue‐light‐emitting 2,7‐carbazole‐based conjugated copolymers have been prepared by Yamamoto or Suzuki cross‐coupling reactions. By introducing highly substituted aromatic comonomers, fully soluble high‐molecular‐weight copolymers have been obtained. Moreover, these amorphous polymeric materials exhibit good thermal stability and interesting redox properties. All these features make these new conjugated polymers highly promising for the development of single‐polymer‐layer blue‐light‐emitting diodes.

     

Single Polyelectrolyte Microcapsules Fabricated By Glutaraldehyde‐Mediated Covalent Layer‐By‐Layer Assembly

Summary: Single polyelectrolyte component microcapsules and multilayers, exemplified by poly(allylamine hydrochloride) (PAH), have been prepared using a method of glutaraldehyde (GA)‐mediated covalent layer‐by‐layer (LbL) assembly. The GA cross‐linking of the adsorbed PAH results in surfaces covered by reactive aldehyde groups, which can then react with PAH to result in another layer of covalently linked PAH. The repeated assembly of single polyelectrolyte in an LbL manner can be thus achieved. The PAH multilayers can grow linearly along with the layer number, and their thickness can be controlled at the nanometer scale, as verified by UV‐vis absorption spectrometry and ellipsometry. Single polyelectrolyte microcapsules are obtained after removal of the template cores at low pH. The morphology and integrity are confirmed by scanning force microscopy and confocal laser scanning microscopy.

Schematic illustration of the preparation of a single polyelectrolyte component microcapsule by GA‐mediated covalent LbL assembly.     

Poly(4‐vinylpyridine) Nanocrosslinked by Polyhedral Oligomeric Silsesquioxane

Summary: Octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was used as the crosslinking agent to prepare the nanocrosslinked poly(4‐vinylpyridine) (P4VP) with POSS content up to 55.2 wt.‐%. The formation of the crosslinked structure is ascribed to the macromolecular reaction between pyridine rings of P4VP and epoxide groups of OpePOSS. The POSS‐crosslinked P4VP displayed enhanced glass transition temperatures (T_gs) and an improved thermal stability in terms of the results of thermal analysis.

Crosslinking of poly(4‐vinylpyridine) with octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane.     

pH‐Disintegrable Polyelectrolyte Multilayer‐Coated Mesoporous Silica Nanoparticles Exhibiting Triggered Co‐Release of Cisplatin and Model Drug Molecules

We report on the fabrication of pH‐disintegrable polyelectrolyte multilayer‐coated mesoporous silica nanoparticles (MSN) capable of triggered co‐release of cisplatin and model drug molecules. The outer polyelectrolyte multilayer was assembled from permanently cationic polyelectrolyte, poly(allyl amine hydrochloride) (PAH), and negatively charged polyelectrolyte, P(DMA‐co‐TPAMA), consisting of N,N‐dimethylacrylamide (DMA) and 3,4,5,6‐tetrahydrophthalic anhydride‐functionalized N‐(3‐aminopropyl)methacrylamide (TPAMA) monomer units, which exhibits pH‐induced charge conversion characteristics. Thus, the subtle alteration of solution pH from 7.4 to ≈5–6 can lead to the disintegration of outer polyelectrolyte multilayers, accompanied with the co‐release of cisplatin and RhB.

     

Non‐Catalyst Synthesis of Functionalized Biodegradable Polycarbonate

The thermal ring‐opening polymerization of 5‐benzyloxy‐trimethylene carbonate (BTMC) in bulk in the absence of any catalyst resulted in high molecular weight poly(BTMC) ( = 80 300) and subsequent catalytic hydrogenolysis resulted in functional poly(5‐hydroxyl‐trimethylene carbonate) (PHTMC). Similar spontaneous polymerization of BTMC in the presence of PEG ( = 2 000) as a macroinitiator can provide amphiphilic block polymers. The results revealed that the thermal non‐catalyst (co)polymerization of BTMC is a highly attractive preparative method because of the lack of usage of toxic initiators or catalysts. Furthermore, an evaluation of the degradation and cytotoxicity of PHTMC demonstrated enhanced degradability compared to poly(trimethylene carbonate) and similar toxicity compared to PLGA, showing PHTMC to be a promising biomaterial.

     

Heterogeneous “Organoclick” Derivatization of Polysaccharides: Photochemical Thiol‐ene Click Modification of Solid Cellulose

A simple and direct method for derivatization of solid polysaccharides is presented. The novel methodology is based on the combination of organic acid‐catalyzed esterification or etherification and photochemical thiol‐ene click derivatization of a heterogeneous polysaccharide. The solid cellulose was “organoclick” modified with aryl, alkyl and polyester groups, respectively. The modification allows for a highly modular and metal free surface modification of solid polysaccharides.

     

Ethylene and Ethylene/Propylene Polymerization Behavior of Bis(phenoxy‐imine) Zr and Hf Complexes with Perfluorophenyl Substituents

The catalytic properties of bis(phenoxy‐imine) Zr and Hf complexes incorporating perfluorophenyl groups with methylaluminoxane were investigated. The fluorinated complexes produced far higher‐molecular‐weight polyethylenes and ethylene/propylene copolymers with increased activities compared with the non‐fluorinated congeners. Moreover, the fluorinated complexes displayed a higher incorporation ability for propylene.

Structures of complexes 1 – 4 .     

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.

     

Novel Spectrally Stable Saturated Blue‐Light‐Emitting Poly[(fluorene)‐co‐(dioctyldibenzothiophene‐S,S‐dioxide)]s

Novel poly[(fluorene)‐co‐(2,8‐dioctyldibenzothiophene‐S,S‐dioxide‐3,7‐diyl)]s were synthesized. The octyl group on the 2,8‐dioctyldibenzothiophene‐S,S‐dioxide (DOSO) unit improved the solubility of the polymers and broadened the optical band gap from 2.95 to 3.20 eV as the content of DOSO unit increases. The electroluminescence (EL) spectra of polymers show CIE coordinates around (0.16, 0.07) independent of the ratio of DOSO units in the polymers, owing to the ICT and steric hindrance dual‐function. A high efficiency of 3.1 cd · A⁻¹ (EQE = 3.9%) was obtained with the configuration of ITO/PEDOT:PSS/polymer/Ba/Al. The results indicate that PF‐3,7DOSOs could be a promising candidate for saturated blue‐emitting polymers with spectral stability and high efficiency.

     

Steric‐Factor‐Directed Alternating Supramolecular Copolymer Composed of Hydrogen‐Bonded Cyclohexanetricarboxamide Units

Hydrogen‐bonded supramolecular copolymers were easily prepared by mixing cyclohexanetricarboxamides with three ( 1 ) and six ( 2 ) alkylsilyl groups, and supramolecular fibers were fabricated. When the composition of 1 and 2 was at or close to equimolarity, the supramolecular copolymer chain was found to have an alternating sequence. This was attributed to the fact that the steric factor of the alkylsilyl side chains effectively controls the unit sequence of the supramolecular polymer chain.

     

Facile Fabrication of Functional Polypyrrole Nanotubes via a Reactive Self‐Degraded Template

Summary: Polypyrrole nanotubes with high electric conductivity and azo function have been fabricated in high yield via an in‐situ polymerization. During the process fibrillar complex of FeCl₃ and methyl orange (MO), acting as a reactive self‐degraded template, directed the growth of polypyrrole on its surface and promoted the assembly into hollow nanotubular structures.

TEM image of uncompleted PPy nanotubes synthesized in MO solutions after reaction for 40 min.     

Layer‐by‐Layer Nano‐Encapsulation of Microbes: Controlled Cell Surface Modification and Investigation of Substrate Uptake in Bacteria

LbL nano self‐assembly coating of A. vinosum with different polyelectrolyte combinations is presented as an example to investigate substrate uptake in bacteria. The effects of surface charge and the formation of a physical barrier provides new insights in the contact mechanisms between the cell surface and insoluble elemental sulfur. Furthermore, uptake of sulfide by encapsulated cells was investigated. Growth experiments of coated cells showed that surface charge did neither affect sulfide uptake nor the contact formation between the cells and solid sulfur. However, increasing layers slowed or inhibited the uptake of sulfide and elemental sulfur. This work demonstrates how defining surface properties of bacteria has potential for microbiological and biotechnological applications.

     

Phosphorylation of Cotton Cellulose with Baker's Yeast Hexokinase

Here we report for the first time on phosphorylation of cotton cellulose using baker's yeast hexokinase and phosphoryl donor adenosine‐5′‐triphosphate. An enzymatic assay was adopted for determination of the degree of phosphorylation of cellulose. This functional modification of cellulose resulted in improved colorability and flame resistance.

Phosphorylated glucopyranose unit of cellulose.     

Novel Cross‐Linked Films Prepared from Hyperbranched Poly(amine‐ester)

Summary: Novel hyperbranched poly(amine‐ester) (HPAE) cross‐linked films were prepared by cross‐linking the terminal hydroxyl groups of HPAE using glutaraldehyde (GA). Atom force microscope and scanning electron microscope revealed their smooth surfaces, dense and homogenous matrices. Property characterizations indicated that these cross‐linked films had good hydrophilicity, relative low protein adsorption, and high tensile strength. Also, their swelling behavior varied with the solvent.

Structure of the hyperbranched poly(amine‐ester).