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Exploring the surface organometallic chemistry on silica of highly electrophilic yttrium complexes is a relatively uncommon endeavor, particularly when focusing on tris‐alkyl complexes characterized by Y−C σ‐alkyl bonds. A drawback with this class of complexes once grafted on silica, is the frequent occurrence of alkyl transfer by ring opening of siloxane groups, resulting in a mixture of species. Herein, we employed a more stable homoleptic yttrium allyl complex bearing bulky η3‐1,3‐bis(trimethylsilyl)allyl ligand to limit this transfer reaction. This strategy has been validated by comparing the reactivity between [Y{ η3‐1,3‐C3H3(SiMe3)2}3] and [Y(o‐CH2PhNMe2)3] with SiO2–700, where the undesired alkyl transfer reaction occurred for [Y(o‐CH2PhNMe2)3] leading to a bipodal [(≡SiO)2Y(o‐CH2PhNMe2)] as major surface species, 2, while [Y{ η 3‐1,3‐C3H3(SiMe3)2}3] resulted selectively in a monopodal species, [(≡SiO)Y{η3‐1,3‐C3H3(SiMe3)2}2], 1. The materials obtained were characterized by DRIFT, solid state NMR, mass balance analysis and EXAFS. Catalyst 1 showed high activity compared to 2 in ethylene polymerization. The catalytic performance of this neutral catalyst 1 was extended to pre‐industrial scale in the presence of hydrogen and 1‐hexene. An unprecedented activity, up to 7400 gPE gcat−1 h−1 was obtained even with very low concentration of scavenger AliBu3 (TIBA/Y=1.2). The obtained HDPE exhibited desired spherical particle morphology with broad molar mass distribution. [ABSTRACT FROM AUTHOR]

Industrial kraft black liquor from maritime pine was oxidised in aqueous, alkaline medium, under air, at 150 °C, with or without a CuO/TiO2 catalyst. The oxidation products were analysed by HPLC, elemental analysis, SEC, FTIR, NMR. The results showed the depolymerisation of lignin, the formation of phenolic compounds in low yields, with vanillin being the main phenolic compound, and the formation of aliphatic compounds in higher yields, with formic, succinic and tartronic acids being the main identified aliphatic compounds. The presence of the catalyst favoured the formation of phenolic and aliphatic compounds. Replacing kraft black liquor by pure kraft lignin as a starting material did not improve the performances of the catalytic oxidation, indicating that lignin purification may not be necessary under our conditions. Switching from a batch reactor to a fixed bed reactor, operating under similar conditions, did not increase the yields of oxidation products but did increase the productivity. This work demonstrates the potential of kraft black liquor to produce a large panel of compounds, including phenolics, aliphatic acids and oxidised lignin, all of which are valuable in the chemical industry. For the first time, a catalytic process for the chemical valorisation of kraft black liquor is presented. [ABSTRACT FROM AUTHOR]

The present study aimed to optimize insulin-loaded chitosan-coated W/O/W multiple emulsions (MEs) by investigating the effect of process variables on the response using Box–Behnken design. Effect of three independent factors, which are, the concentration of the lipophilic surfactant (Span 80) in the primary emulsion, the concentration of the hydrophilic surfactant (Tween 80) in the secondary emulsion, and phase volume ratio (W/O) in the primary emulsion, was studied on three dependent responses, which are particle size, zeta potential, and entrapment efficiency. The optimized ME showed particle size of 193.7 nm and −64.58 mV zeta potential with maximum entrapment efficiency of 91.84%. The in vitro drug release profile from W/O/W ME was studied under two simulated physiological conditions. In vitro drug release behavior followed the Peppas–Sahlin model and showed an initial and rapid release followed by a slower release. The results of the present investigation suggest the potential of the chitosan-coated W/O/W MEs as a promising oral drug delivery system for insulin. [ABSTRACT FROM AUTHOR]

n‐Type‐doped polymers are key elements to fabricate all‐polymer thermoelectric generators but they are challenging to produce. Herein, a new strategy is proposed, which is based on polarity switching upon doping of a donor–acceptor (D–A) copolymer based on diketopyrrolopyrrol (DPP) and quintethiophene (5T) with FeCl3. Polarity switching from p‐type to n‐type is observed upon increasing the doping concentration of FeCl3. An analysis based on nonmonotonic density of states is proposed, which accounts for the main experimental trends and demonstrates that the polarity switch is governed by the electronic band filling that is determined by the dopant concentration. The influence of the curvature of the density of states is in addition discussed and a complete description of the doping induced transport regimes is proposed. This polarity switching depends on the molecular weight Mn of the polymer and shifts to higher FeCl3 concentrations with increasing Mn. This behavior is attributed to the change of the width of the density of states with Mn. The combination of polarity switching and alignment is a means to produce n‐type‐like oriented and conducting polymers with enhanced power factors up to 10 µW K−2 m−1 along the chain direction. [ABSTRACT FROM AUTHOR]

Herein reported is the impact of the functionalization of four different semiconducting polymer structures by a linear siloxane‐terminated side‐chains. The latter is tetrasiloxane (Si4) or trisiloxane (Si3) chains, substituted at their extremity to a pentylene linker. The polymer structure is based on 5,6‐difluorobenzothiadiazole comonomer (PF2), a diketopyrrolopyrrole unit (PDPP‐TT), a naphtalediimide unit (PNDI‐T2), and a poly[bis(thiophen‐2‐yl)thieno[3,2,b]thiophene (PBTTT). The properties of these siloxane‐functionalized polymers are scrutinized and compared with the ones of their alkyl‐substituted polymer analogues. The impact of the alkyl‐to‐siloxane chain substitution clearly depends on the molecular section of the side chains. When a branched 2‐octyldodecyl chain (C20) is replaced by a Si4 chain of same molecular section, the greatest impact is the strong increase of the π‐stacking overlap of the polymer backbones. This effect leads to a significative enhancement of the charge mobility values of the polymers. As in‐plane and out‐of‐plane mobility are increased simultaneously, this π‐overlap enhancement effect happens to be preponderant over the polymer orientation variations. When a linear tetradecyl chain (C14) is replaced by a linear Si3 chain of twice larger molecular section, the polymer structure is profoundly affected. While PBTTT‐C14 is crystalline and purely edge‐on, PBTTT‐Si3 is mesomorphic and shows a mixed face‐on/edge‐on orientation. [ABSTRACT FROM AUTHOR]