Wood deformation leads to rearrangement of molecules at the nanoscale

Wood, as the most abundant carbon dioxide storing bioresource, is currently driven beyond its traditional use through creative innovations and nanotechnology. For many properties the micro- and nanostructure plays a crucial role and one key challenge is control and detection of chemical and physical processes in the confined microstructure and nanopores of the wooden cell wall. In this study, correlative Raman and atomic force microscopy show high potential for tracking in situ molecular rearrangement of wood polymers during compression. More water molecules (interpreted as wider cellulose microfibril distances) and disentangling of hemicellulose chains are detected in the opened cell wall regions, whereas an increase of lignin is revealed in the compressed areas. These results support a new more “loose” cell wall model based on flexible lignin nanodomains and advance our knowledge of the molecular reorganization during deformation of wood for optimized processing and utilization

Infrared and Raman spectra of lignin substructures : Dibenzodioxocin

Vibrational spectroscopy is a very suitable tool for investigating the plant cell wall in situ with almost no sample preparation. The structural information of all different constituents is contained in a single spectrum. Interpretation therefore heavily relies on reference spectra and understanding of the vibrational behavior of the components under study. For the first time, we show infrared (IR) and Raman spectra of dibenzodioxocin (DBDO), an important lignin substructure. A detailed vibrational assignment of the molecule, based on quantum chemical computations, is given in the Supporting Information; the main results are found in the paper. Furthermore, we show IR and Raman spectra of synthetic guaiacyl lignin (dehydrogenation polymer-G-DHP). Raman spectra of DBDO and G-DHP both differ with respect to the excitation wavelength and therefore reveal different features of the substructure/polymer. This study confirms the idea previously put forward that Raman at 532 nm selectively probes end groups of lignin, whereas Raman at 785 nm and IR seem to represent the majority of lignin substructures.Peer reviewe

Ionic Liquid-Based Microemulsions in Catalysis

The design and properties of surface-active ionic liquids that are able to form stable microemulsions with heptane and water are presented, and their promise as reaction media for thermomorphic palladium-catalyzed cross-coupling reactions is demonstrated

The Role of Chain Molecular Weight and Hofmeister Series Ions in Thermal Aggregation of Poly(2-Isopropyl-2-Oxazoline) Grafted Nanoparticles

Thermoresponsive nanoparticles are promising smart materials for many applications. However, a rational design for applications requires a deeper understanding and experimental verification of the various parameters that influence the thermoresponsiveness of the spherical polymer brushes that define most of such nanomaterials. Therefore, we investigate superparamagnetic iron oxide nanoparticles (SPION) grafted with poly(2-isopropyl-2-oxazoline) (6–33 kg mol−1) by temperature-cycled dynamic light scattering and differential scanning calorimetry. The grafting of dense spherical polymer brushes leads to lower aggregation temperatures and transition enthalpies when compared with the free polymer. The transition enthalpy and temperature depend on the polymer shell size and structure. The addition of kosmotropic salts decreases the aggregation temperature following the Hofmeister series

Surface-active Ionic Liquids for Micellar Extraction of Piperine from Black Pepper

The final publication is available via https://doi.org/10.5560/znb.2013-3196.We present the application of ionic liquid-aqueous micellar solutions as isolation media for the pharmaceutically active ingredient piperine from black pepper. Several surface-active ionic liquids including a biodegradable betaine derivative were used for the extraction of piperine, and a strong correlation between extraction yield and the critical micelle concentration of the respective ionic liquid was found. A scaled strategy for the isolation of piperine was developed that allowed recovery and recycling of the aqueous ionic liquid micellar solution for five runs without any loss in extraction efficiency

Thermoresponsive Block Copolymer Grafted on Core-Shell Nanoparticles

Since 1966, when the poly(2-oxazolines) (POx) were discovered, they have undoubtedly been recognized as a polymer class with high synthetic versatility and good biocompatibility, giving access to highly functional and adaptable materials. The poly(2-oxazolines) are prepared through cationic ring-opening polymerization (CROP), which allow for simple control of the reaction condition, mainly due to the absence of undesired termination and even chain transfer are suppressed. Furthermore, the large available number of monomers with different side chain modifications opens the path towards the fabrication of innovative smart materials with a manifold of applications. Taking into account such observations, we envisage the possibility of designing and synthesizing a block-copolymer featured by: (i) a polar side chain (Fragment A), able to trap organic and/or inorganic compounds (e.g. heavy metal in wastewater or active principles for drug delivery applications); (ii) a thermoresponsive scaffold (Fragment B), able to change the interaction with the media by tuning the temperature. Subsequently, we intend to graft these polymers onto iron oxide nanoparticles (high grafting density) or on organic cores. Pursuing this research, herein we report our results involving the synthesis of the two Fragments (A and B) and the consequent grafting system to the nanoparticles. Finally, we point out the test for heavy metal binding in combination with the thermoresponsive behaviour of our products

Influence of Grafted Block Copolymer Structure on Thermoresponsiveness of Superparamagnetic Core–Shell Nanoparticles

The morphology and topology of thermoresponsive polymers have a strong impact on their responsive properties. Grafting onto spherical particles has been shown to reduce responsiveness and transition temperatures; grafting of block copolymers has shown that switchable or retained wettability of a surface or particle during desolvation of one block can take place. Here, doubly thermoresponsive block copolymers were grafted onto spherical, monodisperse, and superparamagnetic iron oxide nanoparticles to investigate the effect of thermal desolvation on spherical brushes of block copolymers. By inverting the block order, the influence of core proximity on the responsive properties of the individual blocks could be studied as well as their relative influence on the nanoparticle colloidal stability. The inner block was shown to experience a stronger reduction in transition temperature and transition enthalpy compared to the outer block. Still, the outer block also experiences a significant reduction in responsiveness due to the restricted environment in the nanoparticle shell compared to that of the free polymer state. The demonstrated pronounced distance dependence importantly implies the possibility, but also the necessity, to radially tailor polymer hydration transitions for applications such as drug delivery, hyperthermia, and biotechnological separation for which thermally responsive nanoparticles are being developed

Crosslinking of floating colloidal monolayers

Crosslinked colloidal monolayers are promising as templates, lithographic masks, filtration membranes, or membranes for controlled release rates in drug delivery. We demonstrate assembly of monodisperse micron-sized polystyrene (PS) beads at an air/water interface, which are transformed into crystalline monolayers using addition of surface-active agents. Vapor annealing methods with solvents (toluene and xylene) and crosslinking agents (divinylbenzene) were investigated regarding their ability to crosslink these floating monolayers directly at the interface, generating crosslinked membranes with crystal size up to 44 cm2, domain size up to 1.9 mm2, and nano-sized pores (100300 nm). The demonstrated fabrication method emphasizes short fabrication time using a simple setup.(VLID)214305