A Lipase‐Responsive Vehicle Using Amphipathic Polymer Synthesized with the Lipase as Catalyst

We describe an enzyme‐responsive polymeric vehicle, which is of great interest in controlled drug delivery, biosensing, and other related areas. The polymer synthesized using lipase as catalyst in DMSO has a favorable molecular structure that is quickly hydrolyzed by lipase in aqueous phase, and allows a fast release of encapsulated molecules.

     

Polymer/Laponite Composite Latexes: Particle Morphology,Film Microstructure,and Properties

Transparent film materials with excellent mechanical and thermal properties were elaborated by drying a latex suspension of armored polymer/Laponite composite particles. Low‐temperature TEM observation of ultrathin cross‐sections of the films indicated a unique network morphology characterized by a “honeycomb” distribution of the Laponite platelets remindful of the original particles morphology.

     

Preparation of a Polyethylene Latex by Catalytic Hydrogenation of a Polybuta‐1,4‐diene‐Based Dispersion

Summary: Fully linear polyethylene‐based latexes have been prepared by the hydrogenation of polybuta‐1,4‐diene dispersions. The latter were synthesized via dispersion ring‐opening metathesis polymerization of cycloocta‐1,5‐diene, and hydrogenated using RuCl₂(PPh₃)₃ as catalyst, without any further treatment. A high hydrogenation efficiency was achieved as demonstrated by different techniques including DSC, and ¹H NMR and FT‐IR spectroscopy. The hydrogenation process could be carried out without detrimental effect on particle size and colloidal stability as evidenced by optical microscopy and light scattering analysis.

Optical microscopy photograph of a polybutadiene‐based dispersion after hydrogenation. No change in size is observed.     

New Monomers Tailored for Direct Electrografting onto Carbon in Water

Electrografting, which is an electropolymerization technique dedicated to the chemisorption of polyacrylates onto conductive surfaces, was actively studied in anhydrous organic media until now. This communication aims at extending this technique to aqueous media for the grafting of polyacrylates onto carbon. The key criterion for the successful electrografting under these not very demanding experimental conditions (water vs. anhydrous organic solvents) is the use of amphiphilic acrylic monomers. The impact of the chemical structure of these new monomers on the coating properties was investigated. Composition of the coatings was analyzed by FT‐IR ATR and XPS, whereas film thickness and morphology were analyzed by ellipsometry and AFM, respectively.

     

Phase Transition Behaviors of Self‐Oscillating Polymer and Nano‐Gel Particles

Summary: Self‐oscillating polymers and nano‐gel particles consisting of N‐isopropylacrylamide and the ruthenium catalyst of the Belousov‐Zhabotinsky reaction have been prepared. In order to clarify the crosslinking effect on the self‐oscillating behavior, the phase transition behaviors were investigated by measuring the transmittance and the fluorescence intensity of the polymer solution and the gel bead suspension. Cooperative effects due to crosslinking will play an important role for the design of nanoactuators.

Chemical structure of poly(NIPAAm‐co‐Ru(bpy)₃).     

Effect of Molecular Weight on Photoinduced Birefringence in a Chiral Liquid Crystalline Azodye Polymer

Summary: The evolution of the photoinduced birefringence in thin films of narrow polymer fractions is studied and compared with the behavior of the non‐fractionated polymer. The Δn_ind value decreases by increasing the degree of polymerization ( ) within the oligomeric range but becomes independent of molecular weight starting from a of ≈70. Thermal pretreatment of the films results in higher photoinduced birefringence. The films show good stability of the photorecording.

Birefringence induced after 10 min, Δn_ind(600) and its growth rate at the same moment versus molecular weight.     

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.

     

Synthesis and Surface Morphology of Tetraaniline‐block‐Poly(L‐lactate) Diblock Oligomers

Summary: Tetraaniline‐block‐poly(L ‐lactide) diblock oligomers are synthesized via ring‐opening polymerization. The diblock oligomers cast from an L ‐lactide selective solvent (chloroform) show spherical aggregates for the leucoemeraldine state, and ring‐like structures that are composed of much smaller spherical aggregates for the emeraldine state. The formation mechanisms of the two different surface morphologies are discussed in detail.

Surface morphology changes induced by oxidation of the aniline segment of tetraaniline‐block‐poly(L ‐lactate) and drying effects.     

A Novel Photopolymerization Initiating System Based on an Iridium Complex Photocatalyst

The use of a photocatalyst (tris(2‐phenylpyridine)iridium [Ir(ppy)₃]) being able to generate both radicals and cations to initiate free radical polymerization and ring opening polymerization is presented. Remarkably, under soft irradiations (fluorescence bulb, sunlight), excellent cationic polymerization profiles and final conversions are obtained. The involved mechanisms are investigated by ESR experiments.

     

Combining RAFT Radical Polymerization and Click/Highly Efficient Coupling Chemistries: A Powerful Strategy for the Preparation of Novel Materials

This paper highlights the powerful combination of reversible addition–fragmentation chain transfer (RAFT) radical polymerization and various click/coupling chemistries. This is not an exhaustive review but rather an overview demonstrating the impressive possibilities that the “marriage” of these two synthetic approaches offers in modern macromolecular design and synthesis.

     

Atomistic Molecular Dynamics Simulation of Surface Grafted PMMA

Properties characteristic of the size, shape, and orientation as well as the rigidity of PMMA end‐grafted to an amorphous silica surface are calculated by use of fully atomistic molecular dynamics simulations with MMA as explicit solvent. Both the number of grafted chains and their tacticity is varied. Firstly, properties of one atactic end‐grafted chain are compared to those of the same chain without any surface being present. Secondly one, two, and four atactic grafted chains are evaluated to study the influence of grafting density (at low surface occupancy) and thirdly, results of single grafted iso‐, syndio‐, and atactic chains, respectively, are compared to elucidate the influence of tacticity. Additionally, the used force field is validated by calculation of the diffusion coefficient of solvent molecules.

     

Uncharged Water‐Soluble Metal‐Bis‐Porphyrins Like Molecular Tweezers for Amino Acids

Some new water‐soluble bis‐porphyrins, constituted of two porphyrin units spaced by means of aliphatic bridges of different lengths, were synthesized and characterized by MALDI‐TOF mass spectrometry, ¹H NMR and UV‐vis spectroscopy. The hydrosolubility of these uncharged compounds was guaranteed from the presence of six long PEG chains bound on the peripheral positions of the two porphyrins. Cobalt and zinc derivatives were also prepared. In the case of Co‐bis‐porphyrin, the appearance of induced circular dichroism (ICD) signals in water solution confirmed the formation of stable complexes with some amino acids, in which the bis‐porphyrin behaves like molecular tweezers.