01750nas a2200217 4500008004100000022001400041245014800055210006900203260007300272300001000345490000800355520086600363653001501229653002501244653002801269653003601297653002701333100002001360700002101380856013101401 2013 eng d a0926-860X00aInfluence of method of preparation of solid, double-metal cyanide complexes on their catalytic activity for synthesis of hyperbranched polymers0 aInfluence of method of preparation of solid doublemetal cyanide  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcAUG a51-600 v4643 a

Catalytic activity of a series of Fe-Zn double-metal cyanide (DMC) complexes with varying structural and acidic properties has been investigated for the synthesis of hyperbranched polyesters (HPs) from glycerol and succinic acid/adipic acid. The DMC complexes were prepared using different complexing and co-complexing agents. Hydrophobicity of the surface, Lewis acidity and micro-mesoporous architecture are the critical features of DMC enabled control on gelation process in preparing HPs of high degree of branching. The micro-mesoporous architecture of DMC acts as a nano-reactor for reactant molecules to form primary condensation products which further polymerize yielding dendrimers. Hyperbranched polyesters of degree of branching as high as 90% could be achieved without gelation using DMC catalysts. (C) 2013 Elsevier B.V. All rights reserved.

10aDendrimers10aDouble-metal cyanide10aheterogeneous catalysis10aHydrophobic solid acid catalyst10aHyperbranched polymers1 aSebastian, Joby1 aSrinivas, Darbha uhttp://library.ncl.res.in/content/influence-method-preparation-solid-double-metal-cyanide-complexes-their-catalytic-activity-002078nas a2200229 4500008004100000022001400041245013900055210006900194260007300263300001200336490000800348520116000356653001901516653002001535653005001555653002501605653001801630653003601648100002001684700002101704856012301725 2014 eng d a0926-860X00aEffects of method of preparation on catalytic activity of Co-Zn double-metal cyanide catalysts for copolymerization of CO2 and epoxide0 aEffects of method of preparation on catalytic activity of CoZn d aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcJUL a300-3080 v4823 a

Co-Zn double-metal cyanide (DMC) complexes are well-known catalysts for ring-opening polymerization of epoxides and co-polymerization of CO2 and epoxides. This work provides an insight on structure-activity relationship of DMC for poly(cyclohexene carbonate) synthesis. Seven samples of DMC were prepared by different methods and mode of reagent addition. Highly active catalyst could be synthesized even without using a co-complexing agent. CO2 adsorption studies revealed that higher the guest-host interaction higher would be the catalytic activity. High density and strength of Lewis acid sites, moderate crystallinity, low crystal symmetry (rhombohedral/monoclinic), Cl- ions and coordinated tert.-butanol (complexing agent) control the catalytic activity for polycarbonates. Chloride in the structure avoided induction period by increasing acidity of the catalyst and thereby, improving the guest-host interactions. Polycarbonates with CO2 incorporation as high as 86 mol%, average molecular weight of 20900 and polydispersity index of 1.8 were prepared at complete conversion of cyclohexene oxide. (C) 2014 Elsevier B.V. All rights reserved.

10aCarbon dioxide10aCO2 utilization10aCopolymerization of CO2 and cyclohexene oxide10aDouble-metal cyanide10aPolycarbonate10aStructure-activity relationship1 aSebastian, Joby1 aSrinivas, Darbha uhttp://library.ncl.res.in/content/effects-method-preparation-catalytic-activity-co-zn-double-metal-cyanide-catalysts-001774nas a2200205 4500008004100000022001400041245013400055210006900189260007300258300001200331490000800343520094400351653002001295653004101315653002501356653001801381100002001399700002101419856012801440 2015 eng d a0926-860X00aFactors influencing catalytic activity of Co-Zn double-metal cyanide complexes for alternating polymerization of epoxides and CO20 aFactors influencing catalytic activity of CoZn doublemetal cyani aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcOCT a163-1720 v5063 a

Co-Zn double-metal cyanides (DMCs) show good catalytic activity towards copolymerization of epoxides and CO2. A deep insight into the structural aspects of the catalysts that control their catalytic performance is addressed in this work. Method of preparation of DMC catalysts was found to have influence on their structure, which in turn dictated their catalytic activity. Complexing agent (t-BuOH) and density of strong acid sites of DMC catalysts were found critical factors responsible for their activity. Selectivity of DMC towards polycarbonates depends on the amount of alkali ion content in their composition. Induction period of the catalysts was governed by the strength of acid sites and by the presence of dispersed ZnCl2 in the composition. This study provides an understanding of the prime features of DMC catalysts that can be tuned for high productivity of polycarbonates. (C) 2015 Elsevier B.V. All rights reserved.

10aCO2 utilization10aCopolymerization of epoxides and CO210aDouble-metal cyanide10aPolycarbonate1 aSebastian, Joby1 aSrinivas, Darbha uhttp://library.ncl.res.in/content/factors-influencing-catalytic-activity-co-zn-double-metal-cyanide-complexes-alternating-0