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Renewable resources such as wood are an important candidate towards the replacement of fossil-based materials with bio-based materials. Lignin, comprising up to 40% of woody biomass, has shown great potential in the preparation of nanoparticles (LNPs), which can be used in diverse material applications. Typically, LNPs are prepared from technical lignins, deriving from pulping processes. Their formation is thought to be driven by the hydroxyl content and molecular weight of lignin. However, other equally important parameters are the monolignol composition and the concentration of lignin used. In this study, we used native-like lignin fractions from hardwood and softwood to investigate the impact of lignin structure on LNP formation. We identified a synergistic effect between 7C-7C stacking and hydroxyl group content in nanoparticle formation. Our LNPs exhibited different morphologies, including compact, collapsed spheres, and 'snowman' aggregates. The results described herein provide an in-depth perspective on the formation and structure-property relationship of LNPs from native -like lignin fractions. With this study we aim to promote biorefinery concepts, in which the lignin structure is preserved during extraction.

Triblock copolymers of ABA- and BAB-type consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA, A) and poly(epsilon-caprolactone) (PCL, B) have successfully been prepared. PDMAEMA-b-PCL-b-PDMAEMA (ABA) and PCL-b-PDMAEMA-b-PCL (BAB) were synthesised by a combination of ring-opening polymerisation of epsilon-CL, atom transfer radical polymerisation of DMAEMA and end-group conversion, performed through either acylation or azide-alkyne "click" chemistry. All samples were analysed by size exclusion chromatography where it was found that the evaluation of PDMAEMA-containing polymers was difficult due to the thermoresponsivity of PDMAEMA, affecting the solubility of the polymer in the temperature range at which the SEC was operated. From differential scanning calorimetry measurements it was shown that the crystallinity could be altered by changing the order of the blocks; with PDMAEMA as the outer block (ABA), the inherent crystallinity of PCL was destroyed while with PCL as the outer block (BAB), the degree of crystallinity was in the same proximity as for a PCL homopolymer.

In the present study, the two grafting techniques grafting-from - by activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) - and grafting-to - by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) - were systematically compared, employing cellulose as a substrate. In order to obtain a meaningful comparison, it is crucial that the graft lengths of the polymers that are grafted from and to the substrates are essentially identical. Herein, this was achieved by utilizing the free polymer formed in parallel to the grafting-from reaction as the polymer for the grafting-to reaction. Four graft lengths were investigated, and the molar masses of the four free polymers (21 ≤ Mn ≤ 100 kDa; 1.07 ≤ M ≤ 1.26), i.e. the polymers subsequently employed in the grafting-to reaction, were shown to be in the same range as the molar masses of the polymers grafted from the surface (23 ≤ Mn ≤ 87 kDa; 1.08 ≤ M ≤ 1.31). The molecular weights of the chains grafted from the surface were established after cleavage from the cellulose substrates via size exclusion chromatography (SEC). High-resolution Fourier transform infrared microscopy (FT-IRM) was employed as an efficient tool to study the spatial distribution of the polymer content on the grafted substrates. In addition, the functionalized substrates were analyzed by X-ray photoelectron spectroscopy (XPS), contact angle (CA) measurements, and field-emission scanning electron microscopy (FE-SEM). For cellulose substrates modified via the grafting-from approach, the content of polymer on the surfaces increased with increasing graft length, confirming the possibility to tailor not only the length of the polymer grafts but also the polymeric content on the surface. In comparison, for the grafting-to reaction, the grafted content could not be controlled by varying the length of the preformed polymer: the polymer content was essentially the same for the four graft lengths. Consequently, the obtained resu

Cellulose surfaces grafted with PMMA of different graft lengths were characterized via high-resolution FT-IR microscopy imaging, visualizing the polymer distribution on the surface. The results from the FT-IR measurements can be compared with the molecular weights obtained from SEC and 1H NMR of the macromolecules formed in solution. © 2012 The Royal Society of Chemistry.

Optical limiting materials are developed for applications in protection of optical sensors against laser aggressions. We have studied functionalised macrocycles (thiacalixarenes) and alkynylplatinum(H) derivatives for optical limiting applications. Glass materials based on alkynylplatinum(H) derivatives and macrocycles were prepared through the sol-gel process. The molecular species were grafted to the matrix in order to maximise the concentration and the stability of the final solid-state material. The glass materials were cut and polished to approximately 1.5 mm. The glass materials show broadband optical limiting in the visible wavelength region, for nanosecond laser pulses.

The synthesis and characterization of dendron-coated 2,5-bis(phenylethynyl)thiophene chromophores are described. The dendrimers were grown divergently on the arylthiophene core with the versatile anhydride of 2,2-bis(methylol)propionic acid. The arylthiophene core was synthesized with Sonogashira coupling reactions. Structurally well-defined dendrimers up to the fourth generation were grown, as confirmed by size exclusion chromatography, NMR, and matrix-assisted laser desorption/ionization time-of-flight analysis. The different dendritic substitution did not influence the absorption spectra of the compounds in or near the visible region. Solutions of arylthiophenes had good transparency at wavelengths greater than 400 nm. The dendritic thiophenes exhibited an optical-power limit at the laser wavelength of 532 nm. However, the magnitude of the optical-power limit of these compounds was slightly lower than that of a nondendritic arylthiophene with n-pentyl substituents. (C) 2005 Wiley Periodicals, Inc.