In this paper, we report on the development of a bench-stable borane for frustrated Lewis pair catalyzed reduction of aldehydes, ketones and enones. The deliberate for finetuning of structural and electronic parameters of Lewis acid component and the choice of Lewis base provided for the first time, a moisture tolerant FLP catalyst. Related NMR and DFT studies underpinned the unique behavior of this FLP catalyst and gave insight into the catalytic activity of the resulting FLP catalyst.

Bicomponent nanophase-separated poly(2-hydroxyethyl methacrylate)-linked-polyisobutylene (PHEMA-l-PIB) amphiphilic conetworks were synthesized by radical copolymerization of methacrylate−telechelic polyisobutylene (MA−PIB−MA) and different amounts of 2-(trimethylsilyloxy)ethyl methacrylate (SEMA) followed by quantitative hydrolysis of the trimethylsilyl protecting groups. The PIB content of the resulting conetworks, determined by elemental analysis and solid-state 1H NMR under fast magic-angle spinning (MAS), varied between 17 and 63% w/w. Phase separation and morphology of these conetworks were investigated by DSC, small-angle X-ray scattering (SAXS), and for the first time by 1H spin diffusion solid-state NMR. Two T g values were observed by DSC in all samples. The observed T g values were close to the literature values of both homopolymers (110 °C for PHEMA and −67 °C for PIB), indicating a strong phase-separated morphology in these conetworks. Parameters were optimized for the 1H spin diffusion NMR experiments, and the measurements were carried out with six filtering cycles and a 10 μs delay between pulses at 90 °C. The NMR and SAXS measurements prove strong phase-separated morphology. The sizes of the hydrophilic (PHEMA) and hydrophobic (PIB) nanodomains were determined to be in the 5−15 nm range. The spin diffusion experiments also indicate strongly separated phases without a detectable interface with mixed components. The long period of our system seems to depend weakly on the volume fraction whereas the morphology of the nanophases depends on the volume fraction.

Differences were found in the plasticizing effects of two commonly used softening materials on amorphous chitosan films. The plasticizing efficiencies for glycerol and PEG 400 were found to be similar in mechanical tests, but the changes in the three-dimensional H-bonded structure monitored by solid-state NMR spectroscopy were different. The analysis of Lee-Goldburg cross-polarization build-up curves demonstrated that, while glycerol decreases the mobility of the acetamide groups, PEG 400 increases it. Further, while glycerol molecules are immobilized in chitosan films, PEG 400 remains mobile in them. The results of two-dimensional (2D) 1 H-13 C frequency-switched Lee-Goldburg (FSLG) HETCOR experiments supported the mobility difference of the chitosan chains and suggested a specific interaction between the glycerol and the glucosamine units. Our findings were supported by density functional theory calculations. Overall, PEG 400 acts as an external plasticizer, while glycerol acts as an internal plasticizer.

Maleic anhydride (MA) grafted poly(lactic acid) (PLA) coupling agents (MAPLA) were prepared by reactive processing. The amount of peroxide initiator and MA was changed in a relatively wide range. Coupling efficiency was checked in PLA/wood composites as a function of grafting degree, coupling agent and wood content. The analysis of the results showed that chain scission takes place in PLA during reactive modification. The occurrence of grafting could not be proved by FTIR spectroscopy, but a detailed NMR analysis showed that the degree of grafting depends on the amount of both reactants; a maximum of 2.5 MA groups/PLA chain could be grafted under the conditions used in the study. The functionalized polymer proved to be an efficient coupling agent in PLA/wood composites. Efficiency increased with increasing number of functionality and coupling agent amount. Coupling resulted in increased strength and reinforcement.Acoustic emission analysis of deformation processes supported by microscopy proved that the dominating local deformation process is the fracture of the fibers, but small extent of debonding also occurs in neat, uncoupled composites. The prevention of debonding by coupling resulted in the improved performance of the composites. Local processes initiate the immediate failure of the composite irrespectively of their mechanism.

The poly [(2-dimethylamino)ethyl methacrylate]-l-polyisobutylene (PDMAEMA-l-PIB) amphiphilic network (APN), a new class of cross-linked systems, was synthesized by the use of methacrylatetelechelic PIB obtained via quasiliving carbocationic polymerization. The swelling dynamics and the free volume changes of this APN was followed by simultaneous swelling and positron annihilation measurements. It was found that the lifetime of ortho positrons (o-Ps) increases with increasing swelling ratio (R), reaches a maximum at relatively low R, and decreases to a constant value at equilibrium swelling. These findings indicate the collapse of the hydrophobic PIB domains and expansion of the hydrophilic PDMAEMA phase in the network upon contacting with water. After reaching the maximum, the decrease of the lifetime parameter is caused by filling the free volume with water in the network. A striking observation was obtained for the o-Ps formation intensity as a function of time (or swelling ratio): the intensity rapidly decreases, and it reaches a minimum at very low R, at ∼10% of the equilibrium swelling ratio, and then increases to a constant value. These phenomena reveal important aspects of the structure of the free volume in the APN and provide fundamental information about the swelling dynamics. The minimum of the o-Ps intensity is reached at around 1:1 water/monomer units molar ratio in the network. Surprisingly, a similar phenomenon was observed when the monomer itself was mixed with water. Molecular modeling by ab initio calculations indicates that a 1:1 ringlike cluster may be formed between water and DMAEMA. On the basis of these results it is concluded that the surface of the free volume units in the APN become covered with water molecules quickly by interacting with the PDMAEMA chains at the beginning of swelling. This indicates that the free volume in the PDMAEMA-l-PIB APN is not composed of independent pores but of interconnected channels which allow rapid diffusion of water molecules to cover the surface of the free volume units. This fast process results in a quick surface structure reorganization, i.e., enrichment of the surface of the channels by PDMAEMA segments leading to the corresponding rapid decrease of o-Ps formation intensity, and to the simultaneous collapse of PIB domains yielding increase of free volume in the network and positron lifetime at the beginning of swelling. Results of this study also allow us to predict that the combined method presented here, i.e., simultaneous swelling kinetics and positron annihilation investigations, can be widely applicable for gaining new information on free volume structure, swelling dynamics, and interactions between material components and swelling agents for a large variety of networks,

The development of a boron/nitrogen-centered frustrated Lewis pair (FLP) with remarkably high water tolerance is presented. As systematic steric tuning of the boron-based Lewis acid (LA) component revealed, the enhanced back-strain makes water binding increasingly reversible in the presence of relatively strong base. This advance allows the limits of FLP's hydrogenation to be expanded, as demonstrated by the FLP reductive amination of carbonyls. This metal-free catalytic variant displays a notably broad chemoselectivity and generality.

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Herein we report that a single frustrated Lewis pair (FLP) catalyst can promote the reductive etherification of aldehydes and ketones. The reaction does not require an exogenous acid catalyst, but the combined action of FLP on H , R-OH or H O generates the required Brønsted acid in a reversible, "turn on" manner. The method is not only a complementary metal-free reductive etherification, but also a niche procedure for ethers that would be either synthetically inconvenient or even intractable to access by alternative synthetic protocols.