Characterization of branched polydisperse polymers. Influence of solvents on the branching parameters

Dobkowski, Z.

doi:10.1002/app.1985.070300131

Cited by 4 publications

(3 citation statements)

References 32 publications

(4 reference statements)

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“…Since an extension of our method for taking into account the presence of the excluded volume effect has not yet been developed [10] we have assumed equality of the expansion factors for branched and linear polymer molecules for obtaining the predictions in Figure 4(b). This assumption has been previously used by several researchers [23] and has not been questioned in more recent works with similar goals as ours. Note that Monte Carlo simulation and molecular dynamics have gone a long way to describe real chains and even branched ones, [24] but the complexity of kinetic schemes such as the one here discussed precludes the direct use of approaches which have successfully tackled simpler structures such as comb and star polymers.…”

Section: Kinetic Step Kinetic Parameters Involved Remarksmentioning

confidence: 72%

Time Programmed Feed of Semi‐Batch Reactors with Non‐Linear Radical Copolymerizations: An Experimental Study of the System Styrene + Divinylbenzene Using SEC/MALLS

Gonçalves

Dias

Costa

2007

Macromolecular Symposia

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Summary:The radical crosslinking copolymerization of mono and divinyl monomers was experimentally studied with a 2.5 dm 3 semi-batch reactor using styrene þ divinylbenzene as a model system. The analysis of products was carried out by SEC with a MALLS detector. The influence of the feed policy of divinylbenzene on the time evolution of the copolymer molecular weights and z-average mean square radius of gyration was assessed. A detailed kinetic model, in the absence of intramolecular reactions but taking into account the presence of the two isomers m-and p-in the commercial divinylbenzene and the different reactivities of the various radicals and double bonds was developed; most parameters have been collected from previous kinetic studies, and only two have been regressed using our measured molecular weights. These results can be used to improve the production of branched/crosslinked polymers with controlled molecular architecture.

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Section: Kinetic Step Kinetic Parameters Involved Remarksmentioning

confidence: 72%

Time Programmed Feed of Semi‐Batch Reactors with Non‐Linear Radical Copolymerizations: An Experimental Study of the System Styrene + Divinylbenzene Using SEC/MALLS

Gonçalves

Dias

Costa

2007

Macromolecular Symposia

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“…branched and linear polymer molecules. Several other researchers [48] have also considered this assumption in more recent works with similar goals as this one, but a more exact estimation of g is urgently needed.…”

Section: Resultsmentioning

confidence: 99%

Molecular Architecture of Non‐Linear Polymers: Kinetic Modeling and Experimental Characterization of the System Methyl Methacrylate + Ethylene Glycol Dimethacrylate

Trigo

Gonçalves

Dias

et al. 2008

Macromolecular Symposia

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A general kinetic approach [l-4) allowing the prediction of the molecular architecture of non-linear polymers is applied to the study of the copolymerization of methyl methacrylate (MMA) with ethylene glycol dimethacrylate (EGDMA). Dynamic predictions of molecular weight distributions, sequence length distributions and mean square radius of gyration are possible before and after gelation. A set of experiences concerning the copolymerization ofMMA and EGDMA was carried out in toluene solution at 60 oc for which classic radical kinetics is a good approximation. The time evolution of some polymers properties was done using a GPC system with a refractive index detector coupled with MALLS. With this combination it is possible the determination of absolute weight average molecular weight and distributions for non-linear polymers, as well as the z-average radius of gyration of the products. Therefore some experimental information about the architecture of the networks can be obtained. The influence of the initial amount of cross-linker on the dynamics of the nonlinear structure of these products was investigated. A complex kinetic scheme comprising 23 different chemical species and 59 chemical reactions was applied in the modeling studies ofthis chemical system. Most of the kinetic parameters used in the simulations were collected from previous studies and a good agreement between predictions and experimental measurements is observed for molecular weights and z-average radius of gyration (see Figures I and 2). These studies can be used to improve the properties of crosslinked!branched polymers which nowadays have important applications in biomedicine or separation processes useful in biotechnology and pharmaceutical industries.

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“…The expression for gx is useful for the investigation of branching only if the architecture of the branched polymer is known since both the exponent x and the final equation required for g are dependent on the type of branching present in the polymer. [19][20][21][22][23][24][25][26] Values for x range from 0.5 to 1.5. For star branched polymers, it has been established that x = 0.5.…”

Section: Introductionmentioning

confidence: 99%

Dilute solution properties of model PMMA-g-PMMA's

Siochi¹,

DeSimone²,

Hellstern

et al. 1990

Macromolecules

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Characterization of branched polydisperse polymers. Influence of solvents on the branching parameters

Cited by 4 publications

References 32 publications

Time Programmed Feed of Semi‐Batch Reactors with Non‐Linear Radical Copolymerizations: An Experimental Study of the System Styrene + Divinylbenzene Using SEC/MALLS

Time Programmed Feed of Semi‐Batch Reactors with Non‐Linear Radical Copolymerizations: An Experimental Study of the System Styrene + Divinylbenzene Using SEC/MALLS

Molecular Architecture of Non‐Linear Polymers: Kinetic Modeling and Experimental Characterization of the System Methyl Methacrylate + Ethylene Glycol Dimethacrylate

Dilute solution properties of model PMMA-g-PMMA's

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