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Even though styrene and acrylamide are among the most abundant monomers, their copolymers are understudied due to the difficulties connected to their synthesis, especially if well-defined structures are desired. This study explores the synthesis and solution properties of poly(styrene-b-acrylamide) block copolymers. We report for the first time the synthesis of such diblock copolymers with RAFT polymerization in homogeneous conditions, utilizing DMSO as a common solvent. Despite their nonpolyelectrolyte nature and a very low content of the hydrophobic comonomer, poly(styrene-b-acrylamide) diblock copolymers have been found to be remarkably good viscosifiers for water. Gelation concentration as low as 1 wt % was observed for copolymers containing as little as 1 mol % of styrene constituting a block less than 10 repeat units long. An irreversible gelation upon heating was observed according to a new mechanism of microgel particle hydration, which is proposed for applications in the fields of biomaterials and 3D printing. The properties are speculated to arise from strong hydrogen bonding within the PAM domains. Amid the current growing focus on polyelectrolytes, this work highlights ubiquitous acrylamide as a building block in nonpolyelectrolyte block copolymers for design of smart soft materials.

This study reports the synthesis of novel poly(1‐vinylimidazole)‐b‐poly(9‐vinylcarbazole) (PVI‐b‐PVK) block copolymers with varying monomer ratios using reversible addition‐fragmentation chain‐transfer (RAFT) polymerization and their incorporation in responsive composite materials. Specifically, non‐covalent exfoliation of two different conductive fillers, multi‐walled carbon nanotubes (MWCNTs) or reduced graphene oxide (rGO), was studied. The percolation threshold of the synthesized nanocomposites was dependent on the polymer used for dispersion, showing a better affinity of the fillers for block copolymers with higher relative carbazole content. Resistivity measurements showed selective variation in the resistance signal when the materials were exposed to various organic solvents and acids, providing a good basis for the design of sensing devices.

Graphical abstract:

Amphiphilic aromatic polymers have been synthesized by grafting aliphatic polyketones with 4-(aminomethyl)benzoic acid at different molar ratios via the Paal–Knorr reaction. The resulting polymers, showing diketone conversion degree of 16%, 37%, 53%, and 69%, have been complexed with the redox-active 2,3,5-triphenyl-2H-tetrazolium chloride, a precursor molecule with which aromatic–aromatic interactions are held. Upon addition of ascorbic acid to the complexes, in situ reduction of the tetrazolium salt produced 1,3,5-triphenylformazan nanoparticles stabilized by the amphiphilic polymers. The stabilized nanoparticles display highly negative zeta potential [−(35–70) mV] and hydrodynamic diameters in the submicron range (100–400 nm). Nonaromatic polyelectrolytes or hydrophilic aromatic copolymers showing low linear aromatic density and high linear charge density such as acrylate/maleate and sulfonate/maleate−containing polymers were unable to stabilize formazan nanoparticles synthesized by the same method. The copolymers studied here bear uncharged nonaromatic comonomers (unreacted diketone units) as well as charged aromatic comonomers, which furnish amphiphilia. Thus, the linear aromatic density and the maximum linear charge density have the same value for each copolymer, and the hydrophilic/hydrophobic balance varies with the diketone conversion degree. The amphiphilia of the copolymers allows the stabilization of the nanoparticles, even with the copolymers showing a low linear aromatic density. The method of nanoparticle synthesis constitutes a simple, cheap, and green method for the production of switchable totally organic, redox-active, pH-sensitive nanoparticles that can be reversibly turned into macroprecipitates upon pH changing.

Polyfunctionalised aldehydes and dihydropyrans are prepared from easily available functionalised 1-alkynes through a two-step silylformylation/aryl migration sequence. The silylformylation process is performed under mild experimental conditions and affords the corresponding β-silylalkenals in high yields. The fluoride-promoted migration step occurs instantaneously with quantitative conversion. The chemo-, regio- and stereoselectivity can be modulated according to the nature and the position of the functional group on the acetylene precursors. When a good leaving group is present in the ω position of the aliphatic chain of the alkyne a cyclisation product is obtained, while α,β-unsaturated aldehydes are generated from propargylic tosylamides. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

For Abstract see ChemInform Abstract in Full Text.