Continuous precipitation polymerization of vinylidene fluoride in supercritical carbon dioxide: modeling the molecular weight distribution

Ahmed, Tamer S.; DeSimone, Joseph M.; Roberts, George W.

doi:10.1016/j.ces.2004.07.078

Cited by 24 publications

(26 citation statements)

References 21 publications

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“…Due to the absence of termination by disproportionation, reasonably narrow dispersities in the range of 1.2–1.6 can be achieved via this synthesis route . Radical VDF polymerization in supercritical CO 2 , yielding a clean dry polymer product after depressurization, was developed by DeSimone and coworkers …”

Section: Poly(vinylidene Fluoride)mentioning

confidence: 99%

Well-defined copolymers based on poly(vinylidene fluoride): From preparation and phase separation to application

Voet

Brinke

Loos

2014

J. Polym. Sci. Part A: Polym. Chem.

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Poly(vinylidene fluoride) (PVDF) has reached the second largest production volume of fluoropolymers in recent years, and its popularity can be ascribed to high thermal stability and chemical inertness combined with its ferroelectric behavior. Copolymerization of vinylidene fluoride with other monomers leads to a wide variety of products with modified or improved properties. Besides commercially available fluorinated random copolymers, well-defined block-, graft, and alternating copolymers based on PVDF received more attention in recent years. PVDF-containing block copolymers that may selfassemble into well-ordered morphologies are of particular interest, being potential precursors for functional nanostructured materials applicable in membranes and electronics. This Highlight provides an overview of the routes developed towards these materials via conventional and controlled polymerization techniques. In addition, it discusses their nanoscopic phase behavior and current and potential applications.

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Section: Poly(vinylidene Fluoride)mentioning

confidence: 99%

Well-defined copolymers based on poly(vinylidene fluoride): From preparation and phase separation to application

Voet

Brinke

Loos

2014

J. Polym. Sci. Part A: Polym. Chem.

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“…Most of the pioneering work and kinetic models were developed using diethyl peroxydicarbonate (DEPDC) as a free radical initiator at temperatures between 60 and 90

°

C and pressures between 200 and 305 bar in both batch and continuous stirred tank reactors . Several models have been developed evaluating the kinetics of free radical initiated polymerization of VF2 using DEPDC as an initiator as well . Free radical initiators are selected for polymerization reactions based on the reaction conditions and the reactivity of the initiator, which is dependent upon the type of initiator and temperature.…”

Section: Introductionmentioning

confidence: 99%

Tert‐butyl peroxyacetate initiated semibatch polymerization of 1,1‐difluoroethylene in supercritical carbon dioxide

Wenzel

Lee

2016

Polymer Engineering & Sci

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Due to its inertness and solubility in vinylidene fluoride, (VF2), supercritical carbon dioxide is used as a replacement solvent for producing polyvinylidene fluoride (PVDF). tert‐butyl peroxyacetate (TBPA) was evaluated for the first time as a free radical initiator for radical chain polymerization of VF2 producing PVDF without use of a dispersion agent in a semibatch reactor using supercritical carbon dioxide. Diethyl peroxydicarbonate (DEPDC) at 75°C has been evaluated in many publications as an initiator in batch and continuous reactors for polymerization of VF2 in supercritical carbon dioxide. The effects of monomer and initiator concentration, agitation, and reaction time upon average molecular weight and polydispersity were evaluated using TBPA as an initiator at 104°C and compared with DEPDC initiated polymerization. It was found that as agitation rate, monomer concentration, and reaction time increased, the average molecular weight of PVDF using TBPA as an initiator increased. Lower concentrations of TBPA were needed compared to DEPDC to produce comparable molecular weights of PVDF. Using TBPA as an initiator at the conditions investigated resulted in lower polydispersity at similar monomer concentrations compared to DEPDC. Average molecular weights using TBPA ranged from 49,900 g/mol to 1.3 million g/mol and polydispersity ranged from 1.3 to 5.4. POLYM. ENG. SCI., 56:435–440, 2016. © 2016 Society of Plastics Engineers

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“…In the precipitation and dispersion polymerization, there are four theories (model) for loci of polymerization reactions; solution polymerization model (all of the polymerization reactions take place in the continuous phase) [3][4][5][6][7], surface polymerization model (initiation take place in the continuous phase but propagation and termination occurs in the thin layer on the surface of the polymer particles) [8,9], interior polymerization model (initiation take place in the continuous phase but propagation and termination occur in the polymer particles) [10][11][12][13], and simultaneous polymerization model (polymerization reactions are able to occur simultaneously in the both dispersed and continuous phases) [14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Modeling of precipitation polymerization II: calculation of macroradicals concentrations in the continuous and dispersed phases

2011

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According to Hunkeler model, precipitation polymerization of acrylic acid in organic media takes place simultaneously in the both dispersed and continuous phases. In this research, a model is presented based on mass balances of individual species. Hence, concentrations of macroradicals and polymer chains, in different chain lengths, were calculated in the both phases. Number-and weightaverage degrees of polymerization and their distributions were concluded in the both dispersed and continuous phases. Calculation of macroradicals concentration was conducted with quasi-steady state approximation (QSSA) as well as without QSSA (based on the governing differential equations). Macroradical precipitate as soon as reaching to critical chain length. Moreover, precipitation is the main termination reaction in the continuous phase. Polymer with critical chain length is the most populated species in the dispersed phase. Comparison of theoretical and experimental results is in good agreement. QSSA theory gives better results than without QSSA theory because occlusion of macroradicals in the dispersed phase does not occur in the precipitation polymerization of water-soluble monomers in the organic media. This article has proved that the polydispersity index (PDI) of polymer product in the precipitation polymerization of acrylic acid in toluene that follows simultaneous polymerization model is less than that of PDI in the other free radical polymerization methods. Centrifugation method was used to sediment fine polymer particles. The yield of reaction was increased by sedimentation process.

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Continuous precipitation polymerization of vinylidene fluoride in supercritical carbon dioxide: modeling the molecular weight distribution

Cited by 24 publications

References 21 publications

Well-defined copolymers based on poly(vinylidene fluoride): From preparation and phase separation to application

Well-defined copolymers based on poly(vinylidene fluoride): From preparation and phase separation to application

Tert‐butyl peroxyacetate initiated semibatch polymerization of 1,1‐difluoroethylene in supercritical carbon dioxide

Modeling of precipitation polymerization II: calculation of macroradicals concentrations in the continuous and dispersed phases

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