Water Influence on the Physico-Chemical Properties and 3D Printability of Choline Acrylate—Bacterial Cellulose Inks

The aim of this work was to study the influence of water as a co-solvent on the interaction between a polymerizable ionic liquid—choline acrylate (ChA)—and bacterial cellulose. Bacterial cellulose dispersed in ChA is a new type of UV-curable biopolymer-based ink that is a prospective material for the 3D printing of green composite ion-gels. Higher cellulose content in inks is beneficial for the ecological and mechanical properties of materials, and leads to increased viscosity and the yield stress of such systems and hampers printability. It was found that the addition of water results in (1) a decrease in the solvent viscosity and yield stress; and (2) a decrease in the stability of dispersion toward phase separation under stress. In this work, an optimal composition in the range of 30–40 wt% water content demonstrating 97–160 Pa of yield stress was found that ensures the printability and stability of inks. The rheological properties of inks and mechanical characteristics (0.7–0.8 MPa strength and 1.1–1.2 MPa Young’s modulus) were obtained. The mechanism of influence of the ratio ChA/water on the properties of ink was revealed with atomic force microscopy, wide-angle X-ray diffraction studies of bacterial cellulose after regeneration from solvent, and computer simulation of ChA/water mixtures and their interaction with the cellulose surface

Synthesis and Physicochemical Properties of Acrylate Anion Based Ionic Liquids

Two polymerizable ionic liquids (or monomeric ionic liquids, mILs) namely 1-butyl-3-methylimidazolium and choline acrylates ([C4mim]A and ChA, respectively) were synthesized using the modified Fukumoto method from corresponding chlorides. The chemical structure of the prepared mILs was confirmed with FTIR and NMR study. Investigation of the thermal properties with DSC demonstrates that both mILs have a Tg temperature of about 180 K and a melting point around 310 K. It was shown that the temperature dependence of FTIR confirm the Tg to be below 200. Both mILs exhibited non-Newtonian shear thinning rheological behavior at shear rates >4 s−1. It was shown that [C4mim]A is able to dissolve bacterial cellulose (BC) leading to a decrease in its degree of polymerization and recrystallisation upon regeneration with water; although in the ChA, the crystalline structure and nanofibrous morphology of BC was preserved. It was demonstrated that the thixotropic and rheological properties of cellulose dispersion in ChA at room temperature makes this system a prospective ink for 3D printing with subsequent UV-curing. The 3D printed filaments based on ChA, containing 2 wt% of BC, and 1% of N,N′-methylenebisacrylamide after radical polymerization induced with 1% 2-hydroxy-2-methylpropiophenone, demonstrated Young’s modulus 7.1 ± 1.0 MPa with 1.2 ± 0.1 MPa and 40 ± 5% of strength and ultimate elongation, respectively

Rhenium(I) Block Copolymers Based on Polyvinylpyrrolidone: A Successful Strategy to Water-Solubility and Biocompatibility

A series of diphosphine Re(I) complexes Re1–Re4 have been designed via decoration of the archetypal core {Re(CO)2(N^N)} through the installations of the phosphines P0 and P1 bearing the terminal double bond, where N^N = 2,2′-bipyridine (N^N1), 4,4′-di-tert-butyl-2,2′-bipyridine (N^N2) or 2,9-dimethyl-1,10-phenanthroline (N^N3) and P0 = diphenylvinylphosphine, and P1 = 4-(diphenylphosphino)styrene. These complexes were copolymerized with the corresponding N-vinylpyrrolidone-based Macro-RAFT agents of different polymer chain lengths to give water-soluble copolymers of low-molecular p(VP-l-Re) and high-molecular p(VP-h-Re) block-copolymers containing rhenium complexes. Compounds Re1–Re4, as well as the copolymers p(VP-l-Re) and p(VP-h-Re), demonstrate phosphorescence from a 3MLCT excited state typical for this type of chromophores. The copolymers p(VP-l-Re#) and p(VP-h-Re#) display weak sensitivity to molecular oxygen in aqueous and buffered media, which becomes almost negligible in the model physiological media. In cell experiments with CHO-K1 cell line, p(VP-l-Re2) and p(VP-h-Re2) displayed significantly reduced toxicity compared to the initial Re2 complex and internalized into cells presumably by endocytic pathways, being eventually accumulated in endosomes. The sensitivity of the copolymers to oxygen examined in CHO-K1 cells via phosphorescence lifetime imaging microscopy (PLIM) proved to be inessential

Формирование структуры и технологичность сплава Al—Zn—Mg—Ca—Fe—Zr—Sc при получении горячекатаного листа и сварного соединения

Process conditions are suggested for manufacturing wrought semi-finished products (2 and 1 mm sheets) from the Al-4.5%Zn-2.5%Mg-2.5%Ca-0.5%Fe-0.2%Zr-0.1%Sc experimental alloy including thermomechanical processing at t = 400450 °С and reduction ratios up to 98 %, as well as softening annealing of the sheet metal at t = 350400 °C for 1—2 hours. It was found that the as-cast structure consists of eutectic phases (Al, Zn)4Ca, Al10CaFe2 5 to 25 gm in size, and a Al2Mg5Zn5 nonequilibrium T-phase located along the boundaries of dendritic cells (Al). Zirconium and scandium form a solid solution with aluminum as a result of solidification. After hot rolling, the structure of 2 mm sheets consists of lineage-oriented discrete intermetallic particles and their conglomerates up to 40 gm in size in the (Al) matrix. The structure of 1 mm sheets features by greater fineness and structure uniformity. The fine structure of deformed semi-finished products was analyzed using transmission electron microscopy (TEM), and this analysis showed that nanoparticles in the Al3(Zr, Sc) phase of the L12 structural type are maximum 20 nm in cross-section. The following level of mechanical properties was achieved in wrought semi-finished products: ultimate strength σв ~ 310330 MPa, yield strength σ0,2 ~ 250280 MPa with relative elongation δ ~ 4.57.0 %. The possibility of TIG welding using standard AMg5 wire as a filler material was studied. It was shown that the new alloy demonstrated no tendency to form hot cracks. According to the results of X-ray tomography, the percentage of porosity in the weld was 1.27 vol.%. The prevalent pore diameter did not exceed 0.2 mm. In general, the resulting structural and qualitative parameters of weld joints contribute to obtaining a strength of 75 % of the strength index of the initial wrought semi-finished products (sheets) achieved by stabilizing annealing at t = 350 °С for 3 hours.Предложены технологические режимы получения деформированных полуфабрикатов (листов толщиной 2 и 1 мм) из экспериментального сплава Al—4,5%Zn—2,5%Mg—2,5%Ca—0,5%Fe—0,2%Zr—0,1%Sc, включающие термомеханическую обработку при температурах t = 400450 °С и степенях деформации до 98 %, а также смягчающий отжиг при t = 350400 °С в течение 1—2 ч для листового проката. Установлено, что литая структура состоит из эвтектических фаз (Al, Zn)4Ca, Al10CaFe2, размером от 5 до 25 мкм, а также неравновесной Т-фазы Al2Mg3Zn3, расположенных по границам дендритных ячеек (Al). Цирконий и скандий образуют с алюминием твердый раствор в результате кристаллизации. После горячей прокатки структура 2 мм-листов состоит из строчечно направленных изолированных интерметалидных частиц и их конгломератов размером до 40 мкм в матрице из (Al). Структура 1 мм-листов характеризуется большей дисперсностью и равномерностью строения. Анализ тонкой структуры деформированных полуфабрикатов с использованием просвечивающий электронной микроскопии показал, что размер наночастиц фазы Al3(Zr, Sc) структурного типа L12 не превышает в сечении 20 нм. В деформированных полуфабрикатах достигнут следующий уровень механических свойств: предел прочности σв ~ 310330 МПа, предел текучести σ0,2 ~ 250280 МПа при относительном удлинении δ ~ 4,57,0 %. Проведены исследования по возможности применения аргонодуговой сварки с использованием в качестве присадочного материала стандартной проволоки СвАМг5. Показано, что новый сплав не проявил склонности к образованию горячих трещин. По результатам рентгеновской томографии величина пористости в сварном шве составила 1,27 об.%. Преобладающий диаметр пор не превышал 0,2 мм. В целом достигнутые структурные и качественные параметры сварных соединений способствуют получению прочности, составляющей 75 % от показателя прочности исходных деформированных полуфабрикатов (листов), что достигается стабилизирующим отжигом при t = 350 °С в течение 3 ч