Using THF and water as solvent, piperazine as a template, a novel two dimensional layered zinc phosphate 1.5[Zn2(PO4)(HPO4)2]·H2O has been prepared solvothermally, and its structure is determined at 293K by Sieme...
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Using THF and water as solvent, piperazine as a template, a novel two dimensional layered zinc phosphate 1.5[Zn2(PO4)(HPO4)2]·H2O has been prepared solvothermally, and its structure is determined at 293K by Siemens Smart 1000 CCD diffractometer monoclinic, P21/c, a=0.81244(3)nm, b=2.61706(12)nm, c=0.83775(3)nm, β=110.981(2)°, V=1.66313(11)nm3, Z=4, R=0.0285, wR=0.0719. The structure con sists of vertex sharing ZnO4, HPO4, and PO4 tetrahedra, and double protonated organic cations, which results in formation of undulating 4 ring chains and 12 ring sheets. A network of hydrogen bonds involving both layer to layer and layer to amine interaction holds the phosphate layer together. CCDC: 200374.
This work deals with the dependence of the z-average mean-square radius of gyration ( z) on the degree of branching(DB) for highly branched copolymers made from the one-pot cocondensation of AB 2 and AB monomers. A ne...
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This work deals with the dependence of the z-average mean-square radius of gyration ( z) on the degree of branching(DB) for highly branched copolymers made from the one-pot cocondensation of AB 2 and AB monomers. A new expression of the degree of branching has been derived. The DB monotonously increases with increasing A group conversion and the fraction of AB 2 monomers. The value of DB calculated in accordance with our formula is lower than that given by Frey and coworkers. Howerver, when the reaction approaches completion, our expression of the degree of branching degenerates into the equation reported by Frey. Furthermore, the z-average mean-square of gyration of the resulting copolymer in the Θ state has been derived on the basis of the classical work developed by Stockmayer, Gordon, Li and Ba. The relationship between DB and z is illustrated by numerical results. The z-average mean-square radius of gyration of the copolymer with a certain weight-average molecular weight monotonously decreases with increasing the degree of branching.
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