Anionic graft polymerization of propylene oxide on starch

Ezra, Gabriel; Zilkha, Albert

doi:10.1016/0014-3057(70)90049-2

Cited by 12 publications

(6 citation statements)

References 21 publications

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“…29 The second linear PPO byproduct, gPOL2, presents a long tailing in the SEC trace and a much higher polydispersity (M w /M n > 1.50). This should be attributed to the chain transfer to PO monomers during the polymerization, [35][36][37][38][39] which generates new initiating sites for linear PPO throughout the polymerization. This chain transfer mechanism inflicts low yield of the gPO brush copolymer.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, traces of unsaturated CdC bond peaks (δ = 5.1-5.3) are found in the 1 H NMR spectrum of gPE1L2, indicating that the mechanism for the formation of this diblock copolymer must involve chain transfer to PO monomer. [35][36][37][38] The presumed side reactions resulting in the two linear copolymer byproducts are depicted in Scheme 2.…”

Section: Resultsmentioning

confidence: 99%

“…By using the same characteristic peaks, we are also able to confirm that both gPE1L1 and gPE1L2 are composed of PPO and PEO; namely, they are both diblock copolymers. Moreover, traces of unsaturated CC bond peaks (δ = 5.1−5.3) are found in the 1 H NMR spectrum of gPE1L2, indicating that the mechanism for the formation of this diblock copolymer must involve chain transfer to PO monomer. − The presumed side reactions resulting in the two linear copolymer byproducts are depicted in Scheme .…”

Section: Resultsmentioning

confidence: 99%

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Thermoresponsive Core−Shell Brush Copolymers with Poly(propylene oxide)-block-poly(ethylene oxide) Side Chains via a “Grafting from” Technique

et al. 2010

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Thermoresponsive brush copolymers with poly(propylene oxide)-block-poly(ethylene oxide) side chains were synthesized via a "grafting from" technique. Near-monodisperse poly(p-hydroxystyrene) was used as the backbone, and the brush copolymers were prepared by sequential metal-free anionic ringopening polymerization of the oxyalkylene monomers, using the phosphazene base (t-BuP 4 ) and the phenolic hydroxyl groups in the backbone to generate the complex multifunctional initiating system. The length and composition of the side chains were varied by changing the feed ratios of the backbone and the side-chain monomers. By inverting the sequence of the monomer addition, two different molecular structures were achieved, with either poly(propylene oxide) or poly(ethylene oxide) linked to the backbone. In all cases, brush copolymers with high molecular weights and low molecular weight distributions were synthesized. The thermoresponsive behavior of the brush copolymers in dilute aqueous solutions was investigated by dynamic/ static light scattering and fluorescence measurements. Temperature-induced intramolecular chain contraction/association and intermolecular aggregation could both be observed at different stages of the heating process. Intermolecular aggregation was more pronounced for the sample with the poly(propylene oxide) blocks located at the periphery. The results from fluorescence spectroscopy indicate the incompletely solvated state of the brush copolymer in aqueous solution at low temperature and the absence of compact hydrophobic domains in some of the aggregates due to the core-shell brushlike molecular structure of the copolymers.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Thermoresponsive Core−Shell Brush Copolymers with Poly(propylene oxide)-block-poly(ethylene oxide) Side Chains via a “Grafting from” Technique

et al. 2010

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“…The abrupt change in morphology and size of the particles indicates that the grafting reaction takes place mainly on the surface of the starch granules [5,6]. could be mainly ascribed to depletion of monomer and formation of a diffusion barrier by the formation of homopoly(N-VP) [11,26,27].…”

Section: Scanning Electron Microscopymentioning

confidence: 99%

A Novel Copolymer: Starch‐g‐Polyvinylpyrrolidone

et al. 2009

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In this study, graft copolymerization of N-vinylpyrrolidone (N-VP) onto starch was carried out in an aqueous medium using azobisisobutyronitrile (AIBN) as initiator. The variables affecting the graft copolymerization, such as monomer and initiator concentrations, reaction time and temperature, were thoroughly examined. In general, grafting of N-vinylpyrrolidone onto starch increased with the increase in time and monomer concentration up to a certain value and then leveled off. Similarly, increase both in initiator concentration and temperature first favored and than impeded the grafting reaction. Optimum conditions established for grafting were as follows: N-VP = 0.7 M, AIBN = 1.5610 -3 M, T = 707C and t = 5 h. Structural changes of the grafted starch were followed by FTIR, intrinsic viscosity and water absorption capacity studies.

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“…Propylene oxide is the most common hydroxyalkylating agent. The process can be performed in aqueous solution, in suspension, or in dimethylsulfoxide in the presence of a catalyst.…”

Section: Introductionmentioning

confidence: 99%

Polyurethane foams with starch

Lubczak

Szczęch

2018

J of Chemical Tech & Biotech

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BACKGROUND In order to meet environmentally friendly (green) chemistry requirements, substrates are increasingly in demand to enable the production of biodegradable polyurethanes. Starch seems to meet the expectations for green polyol components for application in polyurethane foam synthesis, provided that it is previously converted into liquid resin with free hydroxyl groups as a result of hydroxyalkylation. RESULTS The synthesis of oligoetherols based on starch, functionalized with formaldehyde, glycidol and alkylene carbonates was elaborated. All reactions were performed in water as a solvent. The oligoetherols obtained were characterized by IR, 1H‐NMR and MALDI‐ToF spectroscopies. In the next step, the oligoetherols were applied as components for rigid polyurethane foam synthesis. The resulting foams were then tested for the following parameters: the apparent density, water uptake, dimensional stability at the temperature of 100 and 150 °C, thermal conductivity and compressive strength. The thermal resistance of foams was determined both by static and dynamic methods. The parameters of the polyurethane foams such as apparent density, water uptake and polymerization shrinkage are comparable to common rigid polyurethane foams. Several of the polyurethane foams, however, showed significantly higher thermal resistance in comparison with those obtained from standard components. CONCLUSIONS Hydroxyalkylation of starch with formaldehyde, glycidol and alkylene carbonates in water as a solvent results in formation of oligoetherols, which can be applied for the synthesis of polyurethane foams. Several of the polyurethane foams obtained are resistant to long‐term heating even at 200 °C. Additionally, after thermal exposure, their compressive strength is significantly improved. © 2018 Society of Chemical Industry

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Anionic graft polymerization of propylene oxide on starch

Cited by 12 publications

References 21 publications

Thermoresponsive Core−Shell Brush Copolymers with Poly(propylene oxide)-block-poly(ethylene oxide) Side Chains via a “Grafting from” Technique

Thermoresponsive Core−Shell Brush Copolymers with Poly(propylene oxide)-block-poly(ethylene oxide) Side Chains via a “Grafting from” Technique

A Novel Copolymer: Starch‐g‐Polyvinylpyrrolidone

Polyurethane foams with starch

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