We report on the synthesis and characterization of cylindrical molecular brushes based on poly(2oxazoline)s (POx). The dual-functional monomer, 2-isopropenyl-2-oxazoline (IPOx), was first converted to a poly(2-isopropenyl-2-oxazoline), backbone by free radical (PIPOx R ) or living anionic polymerization (PIPOx A ). Quantitative reaction with methyl triflate yields a macroinitiator salt (PIPOxOTf R/A ) for the preparation of molecular brushes via the grafting from approach by living cationic polymerization of 2-oxazolines (2-methyl-, 2-ethyl-, and 2-isopropyl-2-oxazoline). Characterization of the resulting molecular brushes by NMR and FTIR spectroscopy indicates a very high side chain grafting density and quantitative reactions. Visualization of adsorbed molecular brushes by AFM corroborates this assumption. Furthermore, the lower critical solution temperatures of the POx molecular brushes were determined. The transition temperatures were found to be very defined, reversible, and with no noticeable hysteresis.

The photoreduction of CO2 to hydrocarbon products has attracted much attention because it provides an avenue to directly synthesize value‐added carbon‐based fuels and feedstocks using solar energy. Among various photocatalysts, graphitic carbon nitride (g‐C3N4) has emerged as an attractive metal‐free visible‐light photocatalyst due to its advantages of earth‐abundance, nontoxicity, and stability. Unfortunately, its photocatalytic efficiency is seriously limited by charge carriers′ ready recombination and their low reaction dynamics. Modifying the local electronic structure of g‐C3N4 is predicted to be an efficient way to improve the charge transfer and reaction efficiency. Here, boron (B) is doped into the large cavity between adjacent tri‐s‐triazine units via coordination with two‐coordinated N atoms. Theoretical calculations prove that the new electron excitation from N (2px, 2py) to B (2px, 2py) with the same orbital direction in B‐doped g‐C3N4 is much easier than N (2px, 2py) to C 2pz in pure g‐C3N4, and improves the charge transfer and localization, and thus the reaction dynamics. Moreover, B atoms doping changes the adsorption of CO (intermediate), and can act as active sites for CH4 production. As a result, the optimal sample of 1%B/g‐C3N4 exhibits better selectivity for CH4 with ≈32 times higher yield than that of pure g‐C3N4.

A critical bottleneck for the widespread use of single layer graphene is the absence of a facile method of chemical modification which does not diminish the outstanding properties of the two-dimensional sp(2) network. Here, we report on the direct chemical modification of graphene by photopolymerization with styrene. We demonstrate that photopolymerization occurs at existing defect sites and that there is no detectable disruption of the basal plane conjugation of graphene. This method thus offers a route to define graphene functionality without degrading its electronic properties. Furthermore, we show that photopolymerization with styrene results in self-organized intercalative growth and delamination of few layer graphene. Under these reaction conditions, we find that a range of other vinyl monomers exhibits no reactivity with graphene. However, we demonstrate an alternative route by which the surface reactivity can be precisely tuned, and these monomers can be locally grafted via electron-beam-induced carbon deposition on the graphene surface.

POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption.

As a new class of crystalline porous organic materials, covalent organic frameworks (COFs) have attracted considerable attention for proton conduction owing to their regular channels and tailored functionality. However, most COFs are insoluble and unprocessable, which makes membrane preparation for practical use a challenge. In this study, we used surface‐initiated condensation polymerization of a trialdehyde and a phenylenediamine for the synthesis of sulfonic COF (SCOF) coatings. The COF layer thickness could be finely tuned from 10 to 100 nm by controlling the polymerization time. Moreover, free‐standing COF membranes were obtained by sacrificing the bridging layer without any decomposition of the COF structure. Benefiting from the abundant sulfonic acid groups in the COF channels, the proton conductivity of the SCOF membrane reached 0.54 S cm−1 at 80 °C in pure water. To our knowledge, this is one of the highest values for a pristine COF membrane in the absence of additional additives.

Novel statistic copolymers of dialkyl vinylphosphonates have been synthesized via rare earth metal-mediated group transfer polymerization using easily accessible tris-(cyclopentadienyl)ytterbium. The copolymerization parameters have been determined by activity measurements showing the formation of almost perfectly random copolymers (r 1 , r 2 ∼ 1). Thus, the polymerization rate of vinylphosphonate GTP is mainly limited by the steric demand of growing polymer chain end. The obtained copolymers of diethyl vinylphosphonate and dimethyl or di-n-propyl vinylphosphonate show thermoresponsive properties, i.e., exhibit a tunable lower critical solution temperature following a coil−globule transition mechanism, with cloud points between 5 and 92 °C. Hereby, the LCST can be precisely adjusted by varying the comonomer composition and correlates linearly with the content of hydrophilic/hydrophobic comonomer. These thermoresponsive poly(vinylphosphonate)s, exhibiting a sharp and reversible phase transition, and minor environmental effects such as concentration and additives on their cloud point, are promising candidates in biomedical applications.

Poly(2-isopropenyl-2-oxazoline) (PIPOx) and poly(2-vinylpyridine) (P2VP) have been efficiently synthesized using bis(cyclopentadienyl)methylytterbium (Cp2YbMe) as catalyst. The polymerizations of 2-isopropenyl-2-oxazoline (IPOx) and 2-vinylpyridine (2VP) follow a living group-transfer polymerization (GTP) mechanism, allowing a precise molecular-weight control of both polymers with very narrow molecular-weight distribution. The GTP of IPOx and 2VP occurs via N coordination at the rare earth metal center, which has rarely been reported previously. The relative coordination strength of different monomers at the ytterbium center is determined by copolymerization investigations to be in the order of DEVP > MMA > IPOx > 2VP. In combination with living cationic ring-opening polymerization, PIPOx is converted to molecular brushes with defined backbone and poly(2-oxazoline) side chains using the grafting-from method.

We report on the synthesis of brushes of bottle-brushes of poly(2-oxazoline)s on polished glassy carbon (GC) substrates. First, homogeneous and stable poly(2-isopropenyl-2-oxazoline) (PIPOx) brush layers with thicknesses up to 160 nm were created directly onto GC by the self-initiated photografting and photopolymerization (SIPGP) of 2-isopropenyl-2-oxazoline (IPOx). Kinetic studies reveal a linear increase in thickness with the polymerization time. In a second reaction, the pendant 2-oxazoline ring of the PIPOx brushes were used for the living cationic ring-opening polymerization (LCROP) with different substituted 2-oxazoline monomers to form the side chains. Also for the second surface-initiated LCROP from the surface-bound macroinitiator brushes, the thickness increase with the polymerization time was found to be linear and reproducible. Characterization of the resulting bottle-brush brushes by FTIR spectroscopy, contact angle, and AFM indicates a high side chain grafting density and quantitative reactions. Finally, we have demonstrated the possibility of functionalizing the bottle-brush brushes side chain end groups with sterically demanding molecules.