SiO2/MgCl2 (ethoxide type)/TiCl4 Ziegler-Natta catalysts for use in ethylene polymerization and ethylene/1-hexene copolymerization have been prepared using silica with a supported layer of magnesium ethoxide (Mg(OEt)2) as a catalyst precursor, followed by treating with TiCl4 at different Ti/Mg molar ratios, which showed significant effects on the active centers and pore structures of the cataly...

Investigation of complex molecular systems depends on our ability to correlate physical measurements with molecular structure. Interpretation of studies that rely on synthetic polymers is generally limited by their heterogeneity; i.e., there is variation in the number and arrangement of the monomeric building blocks that have been incorporated. Superior physics and biology can be performed with...

Cyclopentadienyl-titanium complexes containing –OC6H4X ligands (X = Cl, CH3) activated with methylaluminoxane (MAO) were used in the homo-polymerization of ethylene, propylene, 1-butene, 1-pentene, 1-butene, and 1-hexene, and also in copolymerization of ethylene with the α-olefins mentioned. The -X substituents exhibit different electron donor-acceptor properties, which is described by Hammett’...

Mechanistic aspects of palladium-catalyzed insertion copolymerizations of ethylene and R-olefins with methyl acrylate to give high molar mass polymers are described. Complexes [(N∧N)Pd(CH2)3C(O)OMe]BAr′4 (2) or [(N∧N)Pd(CH3)(L)]BAr′4 (1: L ) OEt2; 3: L t NCMe; 4: L t NCAr′) (N∧N ≡ ArNdC(R)-C(R)dNAr, e.g., Ar t 2,6-C6H3(i-Pr)2, R t H (a), Me (b); Ar′ t 3,5-C6H3(CF3)2) with bulky substituted R-di...

The propensity of a half-sandwich (η5-tetramethylcyclopentadienyl) dimethylsilylamido Ti-based catalyst bearing an auxiliary diethylboryl-protected pyridyl moiety (Ti-8), activated by methylaluminoxane (MAO) to homopolymerize α-olefins such as ethylene, 1-hexene and styrene as well as to copolymerize styrene with 1,3-cyclohexadiene is described. The reactivity of Ti-8 was investigated in compar...

The investigation of synthetic polymers for biological applications is increasing as assembly techniques for generating welldefined macromolecules from artificial building blocks become more sophisticated. Synthesis techniques have now evolved such that a wide variety of functional groups can be tolerated by polymerization catalysts, and a fascinating and diverse range of macromolecular and pol...

The palladium(II) complex [Pd(C(6)F(5))Cl(bpzm*)] (5) [bpzm* = bis(3,5-dimethylpyrazol-1-yl)methane] was characterized by (1)H,(1)H-TOCSY, (1)H-NOE difference spectra, (1)H,(19)F-HOESY and (13)C,(1)H-HMBC 2D-NMR techniques. Chemical exchange of the methylene protons from (1)H,(1)H-NOESY cross peaks and exchange of the ortho- and meta-fluorine atoms, respectively, from (19)F,(19)F-EXSY cross pea...

A valuable approach for creating synthetic polymers is the ring-opening metathesis polymerization (ROMP). Welldefined metal carbene catalysts have been devised that afford control over the polymer chain length and architecture. In addition, ruthenium carbene initiators have been developed with excellent air stability and functional group tolerance. These catalysts enable the synthesis of polyme...

•Thiol-ene-epoxy photochemistry for patterning diverse mechanical properties•Materials possess a stable three-orders-of-magnitude difference in Young’s modulus•Demonstration of low-cost, 3D-printed multimodulus wearable braille display Numerous research efforts seek to realize “augmented humanity,” whereby technology enhances human performance by closely interfacing engineered devices with our ...

Polysaccharides are known as natural and renewable feed stock for synthesizing high performance macromolecular materials. The popular, versatile and convenient way to develop polysaccharide is being based on materials used for the grafting of synthetic polymers onto natural polysaccharides. Although the attractive chemical and physical properties of polysaccharide co-polymeric materials, undesi...