Green Nanocomposites from Renewable Resources: Biodegradable Plant Oil‐Silica Hybrid Coatings

Green nanocomposite coatings based on renewable plant oils have been developed. An acid‐catalyzed curing of epoxidized plant oils with 3‐glycidoxypropyltrimethoxysilane produced transparent nanocomposites. The hardness and mechanical strength improved by incorporating the silica network into the organic polymer matrix, and good flexibility was observed in the nanocomposite. The nanocomposites showed high biodegradability.

     

Simulation of Styrene Polymerization by Monomolecular and Bimolecular Nitroxide‐Mediated Radical Processes over a Range of Reaction Conditions

Simulations of polymerization rate, molecular weight development and evolution of the concentrations of species participating in the reaction mechanism over a range of operating conditions, and a parameter sensitivity analysis showing the effects of temperature, activation/deactivation equilibrium constant and initial concentrations of controller and initiator (if present) on these variables are presented for the nitroxide‐mediated radical polymerization of styrene. The simulations were performed with a computer program based on a detailed reaction mechanism. The simulated profiles of conversion, number average molecular weight ( ), and polydispersity agree well with experimental data. Previously unknown activation energies for reactions involved in the mechanism are estimated. The temperature dependence of the kinetic rate constants obtained in this study will be useful for future modeling and optimization studies.

     

The Advantages of In Situ Surfactant Generation for Miniemulsions

The stabilisation of miniemulsions using an in situ generated surfactant is presented. This surfactant, prepared from of a water‐soluble base and an oil‐soluble long chain acid was successfully used to create stable miniemulsions with up to 60 vol.‐% organic phase. It is shown that the creation of a surface active species at the oil–water interface allowed stable miniemulsions to be generated more rapidly than when using conventional surfactant. In addition, polymerised miniemulsions exhibited less secondary nucleation when in situ surfactants were used.

     

Synthesis of Polyaniline Nanobelts

Summary: Polyaniline nanobelts have been synthesized by a self‐assembly process using the chemical oxidative polymerization of aniline in a surfactant gel. The morphologies of polyaniline nanostructures were characterized by field‐emission scanning electron microscopy and transmission electron microscopy. The effects of the concentrations of cetyltrimethylammonium bromide on the morphologies of polyaniline nanostructures have also been investigated.

A scanning electron microscopy image of polyaniline nanobelts synthesized with 0.12 M cetyltrimethylammonium bromide at −7 °C.     

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.     

Solvent Controlled Multi‐Morphological Self‐Assembly of Amphiphilic Graft Copolymers

Summary: Amphiphilic graft polyphosphazenes (EtTrp/PNIPAm‐PPP) with different mole ratios of hydrophobic groups to hydrophilic segments were synthesized by ring‐opening polymerization and subsequent substitution reactions. The self‐assembly behavior of these graft copolymers was studied in detail by TEM, SEM, CLSM, and AFM. Depending on the copolymer composition and common organic solvent employed in dialysis process, supramolecular aggregates ranging from network, nanospheres, high‐genus particles to macrophage‐like aggregates were produced with graft copolymers.

     

Kinetic Monte Carlo Studies on the Importance of the Reaction Scheme in Segmental Exchange of Copolymer Chains

Kinetic Monte Carlo studies (confirmed by integration of the corresponding differential equations) are used to demonstrate the fundamental differences between the two most often accepted schemes of segmental exchange. Modeling of reshuffling systems, originally composed of homopolymers of various , various mass distributions, and different compositions, is carried out until the equilibrium copolymers are obtained. It is shown that one of the schemes leads always to a random microstructure (Bernoulli statistics) whereas modeling of the other one indicates possibility of formation of all achievable distributions of comonomer units (from multiblock to nearly alternate). The concepts of the degrees of randomness and reshuffling are discussed and new definitions are proposed.

     

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.

     

Selectivity in Polystyryllithium Chain Coupling Induced by Monobromoalkane Additives

Summary: The end coupling of living PSLi chains in hydrocarbon media by the addition of monoalkylbromides has been examined. A very selective PS–PS coupling reaction was obtained with neo‐pentylbromide (94%) at a ratio of PSLi/alkylbromide equal to 1 while the secondary and tertiary bromine derivatives yield only very limited coupling. The coupling mechanism is likely to involve a lithium‐bromine interchange at the PS chain end, generating polystyryl‐bromide which then reacts selectively with the remaining polystyryllithium chains.

     

Nanocomposites of Size‐Tunable ZnO‐Nanoparticles and Amphiphilic Hyperbranched Polymers

Highly dispersed ZnO nanoparticles with variable particle sizes were successfully prepared within an amphiphilic hyperbranched polyetherpolyol matrix via decomposition of an organometallic precursor in the presence of air leading to stable nanocomposites. The high degree of stabilization during and after the synthesis by the polymer permits control over the nanoparticle size and therefore, due to the quantum‐size‐effect, the particle properties. Furthermore, these polymer‐inorganic nanocomposites can easily be dispersed in apolar solvents to yield highly transparent, stable solutions.

     

A Mixed Ruthenium Polypyridyl Complex Containing a PEG‐Bipyridine Macroligand

Summary: An amino‐functionalized bipyridine ligand was prepared in order to serve as a bridging unit to an activated low‐molecular‐weight monomethyl ether of poly(ethylene glycol) (PEG). Coordination of a ruthenium(II ) phenantroline precursor onto the formed PEG‐containing bipyridine ligand yielded a metal‐containing polymer which shows interesting properties for solar cell applications.

A schematic of the described polymeric ruthenium(II ) complex and its absorption and emission properties.     

Energy Transfer from Locally Excited π* to Charge Transfer Ground States in a Silylene–π Hetero‐Junction Polymer

Summary: The silylene–π conjugating polymer, poly(di‐n‐hexylsilylenephenylene‐ethynylenephenylene) ( 1 ) adopted a fairly flexible coil‐like conformation due to the bent structure of silylene moiety and showed a unique photoexcited energy transfer behavior. The UV‐vis absorption and steady‐state/time‐resolved photoluminescence studies revealed the occurrence of an intramolecular photoexcited energy transfer (IET) between locally excited π* to charge transfer ground states as well as an intramolecular charge transfer (ICT).

The silylene–π conjugating polymer, poly(di‐n‐hexylsilylenephenylene‐ethynylenephenylene) showing a unique photoexcited energy transfer behavior.     

Prediction of Polymer Properties from their Structure by Recursive Neural Networks

Summary: We propose a new approach for predicting polymer properties from structured molecular representations based on recursive neural networks. To this aim, a structured representation is designed for the modeling of polymer structures. This representation can also account for average macromolecule characteristics. Preliminarily, this model is applied to the calculation of the T_g of (meth)acrylic polymers with different stereoregularity.

Representation of poly(methyl methacrylate) as a chemical tree and unfolding of the encoding process through its structure.     

A Novel Approach for Incorporation of Mono‐Functional Bioactive Phenols into Polyanhydrides

Antiseptics based on phenol and phenolic derivatives were chemically incorporated into polyanhydrides as pendant groups via ester linkages. Polyanhydrides with antiseptic loadings of 46–58 wt.‐% were obtained with molecular weights ranging from 9 400–23 000. In general, polymers with the bulkier antiseptics were more difficult to polymerize and yielded lower molecular weights. All polyanhydrides were amorphous with glass transition temperatures ranging from 27–58 °C. Polymers were deemed noncytotoxic after culturing L929 mouse fibroblast cells in media containing the polymers at two concentrations (0.10 and 0.01 mg · mL⁻¹) over three days. In summary, mono‐functional bioactives can be chemically incorporated into noncytotoxic polyanhydrides.

     

Interface Dissipative Mechanisms in an Elastomeric Matrix Reinforced with MWCNTs

Dissipative mechanisms occurring at the interface between multiwall nanotubes (MWCNT) and an elastomeric matrix are investigated and quantitatively predicted through analytical equations derived from a micromechanical model. The effects of MWCNT aspect ratio on dissipative properties of the reinforced system are investigated at high strains (100–300%). Cyclic tensile tests illustrate that the fraction of dissipated strain energy increases with the amount of MWCNT and varies with their aspect ratio. Lower mean diameter MWCNT are able to dissipate a higher amount of strain energy. The model developed on the basis of the shear lag theory correctly predicts the dissipated strain energy at high strains, taking into account the different contributions to the mechanical behavior of nanotubes' different aspect ratios.