A systematic nomenclature for cascade polymers

Cascade (dendritic) polymers are discrete, highly branched, monodisperse polymers that possess branching patterns described by a mathematical progression. A systematic nomenclature that accurately represents these molecules is described. © 1993 John Wiley & Sons, Inc.     

Synthesis of well‐defined second‐generation dendritic polymers of isoprene (I) and styrene (S): (S2I)3, (SI′I)3, (I″I′I)3, and (I′2I)4

The synthesis of second‐generation (G‐2) dendritic polymers of isoprene (I) and styrene (S) was achieved with anionic polymerization high‐vacuum techniques and by performing the following steps: (1) selective reaction of a living chain with the chlorosilane group of 4‐(chlorodimethylsilyl)styrene (a dual‐functionality compound) to produce a macromonomer, (2) addition of a second living chain (same or different) to the double bond of the macromonomer, (3) polymerization of I with the anionic sites, and (4) reaction of the produced off‐center living species with trichloromethyl silane or tetrachlorosilane (CH₃SiCl₃ or SiCl₄). The combined characterization results showed that the G‐2 dendritic macromolecules synthesized—(S₂I)₃, (SI′I)₃, (I″I′I)₃, (I′₂I)₄—have a high molecular and compositional homogeneity. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1519–1526, 2002     

Dynamic complexity of optimal paths and discount factors for strongly concave problems

We study the relationship between the dynamical complexity of optimal paths and the discount factor in general infinite-horizon discrete-time concave problems. Given a dynamic systemx _t+1=h(x _t ), defined on the state space, we find two discount factors 0 < ^{* **} < 1 having the following properties. For any fixed discount factor 0 < < ^*, the dynamic system is the solution to some concave problem. For any discount factor ^** < < 1, the dynamic system is not the solution to any strongly concave problem. We prove that the upper bound ^** is a decreasing function of the topological entropy of the dynamic system. Different upper bounds are also discussed.This research was partially supported by MURST, National Group on Nonlinear dynamics in Economics and Social Sciences. The author would like to thank two anonymous referees for helpful comments and suggestions.     

On a class of functions with equal infima over a domain and its boundary

In this paper, we present a class of functions:f:X such that inf _xX f(x)= , whereX is a nonempty, finitely compact and convex set in a vector space andB _x ={xX: y aff(X){x:[x, y]X={x}. Our main tool is a recent minimax theorem by Ricceri (Ref. 1).     

非线型聚苯类大分子的研究进展

对支化及树枝状聚苯、环状聚苯、环状聚苯乙炔以及环蕃等几类以苯环为基本结构单元的非线型大分子的研究, 特别是合成作了综述。     

Multiparticle fractal aggregation

Kinetic fractal aggregation in a particle bath where a fractionf of the sites are initially occupied is studied withd=2 computer simulations. Independent particles diffusing to a fixed cluster produce an aggregate with fractal dimensionD 1.7 up to a correlation length(f). At larger lengthsD2.(f) asf 0. When the particles remain fixed but the cluster undergoes a rigid random walkD appears constant at larger scales but varies withf. D 1.95 at largef andD 1.7 asf 0. In both cases, the aggregate sizeN(t) grows with timet ^(f) . Aggregation on a surface by independently diffusing particles produces shapes reminiscent of electrochemical dendritic growth. The dependence of growth rate and geometry is studied as a function of particle concentration and sticking probability.     

铜(Ⅱ)、锰(Ⅱ)、镍(Ⅱ)高分子配合物的合成、表征与催化性质研究

合成出以乙二胺为核，马来酸酐为支化结构单元的马来酰胺树枝状高分子、高分子配体及其铜、锰、镍配合物，通过凝胶渗透色谱、红外光谱、紫外光谱、X-射线光电子能谱等对产物进行了结构表征，并就金属配合物对催化分解双氧水反应进行了研究。     

树状催化剂在不对称氢转移反应中的回收循环使用研究

以(1S,2R)-降麻黄碱为核心的第三代手性树状催化剂在对苯乙酮的不对称氢转移反应中可以方便的回收并循环使用. 该树状催化剂可以一共使用3次而保持对映选择性基本不变.     

Alternating and Random Copolymers of Vinyl Acetate and Maleic Anhydride

Alternating copolymers of vinyl acetate (VAc) and maleic anhydride (MA) are produced preferentially when VAc and MA are copolymerized at moderate temperatures while random copolymers are produced at temperatures above 90°C. A charge-transfer complex (CTC) of VAc/MA exists at moderate temperatures but does not exist at temperatures above 90°C.