Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates

Sebastian, Joby; Srinivas, D.

doi:10.1007/s12039-014-0573-4

Cited by 11 publications

(6 citation statements)

References 35 publications

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“…As shown in the figure, all of M w , M n and M w / M n decrease with the molar ratio of core to monomer increasing. This phenomenon is in agreement with other work (Schüll and Frey, 2013; Sebastian and Darbha, 2014; Hossein et al , 2015; Bharathi and Moore, 2000; Chen et al , 2014; Geladé et al , 2011), in which the presence of a core molecule decreased the molecular weight of hyperbranched polymer with a concurrent reduction in the molecular weight distribution. It is worth noting that all of M w , M n and M w / M n are lower than those of Hupea polymers synthesized by “one-pot” method.…”

Section: Resultssupporting

confidence: 93%

Hyperbranched unsaturated polyester amide synthesized by two-step method

Zheng

Song

2019

PRT

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Purpose Hyperbranched poly(ester-amide)s (HPEAs) have been synthesized from diethanolamine and maleic anhydride with ethylene glycol as a core monomer by using a two-step method, which are marked as Hupea polymers, and dehydration was carried out in xylene under reflux. Design/methodology/approach In comparison with Hupea polymers was synthesized by one-pot method, Hupea polymers synthesized by two-step method has different structure and rheological properties. The intermediate monomer and the resulting polymer are characterized by FTIR and NMR spectroscopies. Findings All of Mw, Mn and Mw/Mn of the hyperbranch polymers decrease with the core/monomer molar ratio increasing. The intrinsic viscosity ([η]) of the polymers decreases with Mw increasing in the investigated range of Mw and scales as [η]∼Mw-0.82, which implies that the molecular weight grew faster with core/monomer molar ratio decreasing than the volume in the investigated range of core/monomer molar ratio. Research limitations/implications The hydrodynamic radius was calculated by using Einstein’s equation and scales as Rh ∼ Mw0.061, and the lower exponent reveals the slow growth in the volume of Hupea molecule. In addition, the viscosity of Hupea polymer in concentrated aqueous solution is independent of shear rate and slightly dependent on molecular weight. Practical implications Hyperbranched poly(ester-amide)s (HPEAs) were synthesized by using a two-step method, which had different structure and rheological properties. Originality/value Hupea polymers show different features from Hupea polymers in structure and rheological properties, which revealed that the synthesis process of HPEA has effect on its performance.

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Section: Resultssupporting

confidence: 93%

Hyperbranched unsaturated polyester amide synthesized by two-step method

Zheng

Song

2019

PRT

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“…For example, Co–Zn double-metal cyanides show a shift of this band from 2133 to 2187 cm –1 , compared to the precursor K 3 Co(CN) 6 . The ν(CN) shift to higher frequencies demonstrates that the CN ion acts as not only a σ-donor by donating electrons to Fe but also as a π-electron donor by chelating to Mn metal. , Additionally, the existence of complexing agent ( tert -BuOH) in the Fe–Mn catalyst was confirmed from the characteristic bands at 1440.7 cm –1 –1261.4 cm –1 (symmetric and antisymmetric C–H deformation and out-of-plane C 3 C–O antisymmetric stretching vibrations) and 1103.2 cm –1 (CH 3 rocking vibrations). ,, Furthermore, a broad band attributed to OH in H 2 O and tert -butanol was detected around 3650 cm –1 . , …”

Section: Results and Discussionmentioning

confidence: 85%

“…30,40 Additionally, the existence of complexing agent (tert-BuOH) in the Fe−Mn catalyst was confirmed from the characteristic bands at 1440.7 cm −1 −1261.4 cm −1 (symmetric and antisymmetric C−H deformation and out-of-plane C 3 C−O antisymmetric stretching vibrations) and 1103.2 cm −1 (CH 3 rocking vibrations). 21,41,42 Furthermore, a broad band attributed to OH in H 2 O and tert-butanol was detected around 3650 cm −1 . 21,42 Diffuse-Reflectance UV−Visible Spectra.…”

Section: ■ Introductionmentioning

confidence: 97%

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Transesterification of Propylene Carbonate with Methanol Using Fe–Mn Double Metal Cyanide Catalyst

Song

Subramaniam

Chaudhari

2019

ACS Sustainable Chem. Eng.

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A highly active and selective heterogeneous catalyst consisting of Fe–Mn double metal cyanide is reported for the transesterification of cyclic carbonates with methanol. Fe–Mn double metal cyanide complex with a Fe/Mn metal ratio of 8 was found to provide significantly higher TOF and stability for transesterification of propylene carbonate with methanol to dimethyl carbonate. The experimental results showed that Mn content has a significant influence on the catalytic activity. TEM and XRD analyses suggested that Fe–Mn complex represents a cubic crystalline structure. XPS analysis showed that all Fe exists in Fe2+ state. However, for the Mn element, 86.8% of Mn exists in Mn2+ state with only 13.2% in Mn4+ state. Furthermore, FTIR and DRIFT UV–vis results verified the formation of a new mixed-metal complex of ferrocyanide moiety and Mn ions via bridging cyanide ligands. NH3-TPD results showed that Fe–Mn double metal cyanide has a strong acidity, which correlates to the high activity of Fe–Mn double metal cyanide complex. The effects of catalyst loading, methanol/PC ratio, temperature, and different cyclic carbonate substrates (ethylene carbonate, propylene carbonate, and 1,2-butylene carbonate) on the initial reaction rate as well as concentration–time profiles are reported. Unique feature of this catalyst is also nonleaching characteristics during reaction and higher TOF unlike the conventional catalysts such as CaO. Compared with the results from Fe and Mn alone as catalysts, Mn in this complex was proposed to be acting as active species, while Fe acting as a metal-dispersing agent and a stabilizer of the cyano-bridged complex and ensures a truly heterogeneous catalyst. On the basis of this, a possible reaction mechanism was proposed. The results presented in this work provide useful insights on the reaction mechanism of transesterification using Fe–Mn double metal cyanide catalysts, which may also be useful to guide rational design of improved catalysts and process for transesterification of cyclic carbonates.

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“…That implies that DMC catalyst structure in particular the basic equivalents is an important issue, as it determines an internal rate of protonation. It seems that the importance of the protonation is not adequately considered in the mechanistic description [116][117][118][119][120][121][122], and with that the susceptibility of a catalyst to incorporate CO 2 in the backbone. This is, so far as we can understand, the catalytic action today, a crucial extension to mechanisms proposed in the open literature [70,[123][124][125][126].…”

Section: Scheme 6 Ppec Formation By Dmc With Anionic Sites (Alternatmentioning

confidence: 99%

DMC-Mediated Copolymerization of CO2 and PO—Mechanistic Aspects Derived from Feed and Polymer Composition

Stahl

Luinstra

2020

Catalysts

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The influence of composition of liquid phase on composition of poly(propylene ether carbonates) in the copolymerization of CO2 with propylene oxide (PO), mediated by a zinc chloride cobalt double metal cyanide, was monitored by FT-IR/CO2 uptake/size exclusion chromatography in batch and semi-batch mode. The ratio of mol fractions of carbonate to ether linkages F (~0.15) was found virtually independent on the feed between 60 and 120 °C. The presence of CO2 lowers the catalytic activity but yields more narrowly distributed poly(propylene ether carbonates). Hints on diffusion and chemistry-related restrictions were found underlying, broadening the distribution. The incorporation of CO2 seems to proceed in a metal-based insertion chain process, ether linkages are generated stepwise after external nucleophilic attack. The presence of amines resulted in lower activities and no change in F. An exchange of chloride for nitrate in the catalyst led to a higher F of max. 0.45. The observations are interpreted in a mechanistic scheme, comprising surface-base-assisted nucleophilic attack of external weak nucleophiles and of mobile surface-bound carboxylato entities on activated PO in competition to protonation of surface-bound alkoxide intermediates by poly(propylene ether carbonate) glycols or by surface-bound protons. Basic entities on the catalyst may promote CO2 incorporation.

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Solid, double-metal cyanide catalysts for synthesis of hyperbranched polyesters and aliphatic polycarbonates

Cited by 11 publications

References 35 publications

Hyperbranched unsaturated polyester amide synthesized by two-step method

Hyperbranched unsaturated polyester amide synthesized by two-step method

Transesterification of Propylene Carbonate with Methanol Using Fe–Mn Double Metal Cyanide Catalyst

DMC-Mediated Copolymerization of CO2 and PO—Mechanistic Aspects Derived from Feed and Polymer Composition

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