Search Results
SET-LRP in biphasic mixtures of fluorinated alcohols with water
2018, Moreno, Adrian, Liu, Tong, Ding, Liang, Buzzacchera, Irene, Galià, Marina, Möller, Martin, Wilson, Christopher J., Lligadas, Gerard, Percec, Virgil
Biphasic-binary mixtures of 2,2,2-trifluoroethanol (TFE) or 2,2,3,3-tetrafluoropropanol (TFP) with water were used as reaction media to synthesize well-defined poly(methyl acrylate) (PMA) with chain end functionality close to 100% by SET-LRP. Non-activated Cu(0) wire was used as a catalyst, taking advantage of the Cu(0)-activation property that these fluorinated alcohols possess. Biphasic-binary mixtures of water, containing a ligand and Cu(II)Br2 either generated by disproportionation of Cu(I)Br or externally added, and an organic solvent, containing a monomer and a polymer, were studied. Two N-ligands were investigated: the classic tris(2-dimethylaminoethyl)amine (Me6-TREN) and tris(2-aminoethyl)amine (TREN), as a more economically attractive alternative for technological purposes. The results reported here support the replacement of Me6-TREN by TREN, taking into account the fact that the latter requires small loadings of an externally added Cu(II)Br2 deactivator and a ligand in the water phase to mediate a living radical polymerization process. Both catalytic systems ensure efficient SET-LRP processes with first order kinetics to high conversion, linear dependence of experimental Mn on conversion, narrow molecular weight distribution, and near-quantitative chain end functionality.
Construction of cost-effective bimetallic nanoparticles on titanium carbides as a superb catalyst for promoting hydrolysis of ammonia borane
2018, Guo, Zhangwei, Liu, Tong, Wang, Qingtao, Gao, Guanhui
Bimetallic cost-effective CoNi nanoparticles (NPs) are conveniently supported on titanium carbides (MXene) by a simple one-step wet-chemical method. The synthesized CoNi/MXene catalysts are characterized by XPS, TEM, STEM-HAADF and ICP-AES. The as-prepared CoNi NPs with a size of 2.8 nm are well dispersed on the MXene surface. It is found that among the CoNi bimetallic system, Co0.7Ni0.3 shows the best performance toward catalyzing ammonia borane (AB) decomposition with a turnover frequency value of 87.6 molH2 molcat−1 min−1 at 50 °C. The remarkable catalytic performance is attributed to the mild affiliation of MXene to NPs, which not only stabilizes NPs to maintain a good dispersion but also leaves sufficient surface active sites to facilitate the catalytic reaction.