Upper Molecular Weight Limit for the Characterization of Polystyrene in Gel Permeation Chromatography

Slagowski, Eugene L.; Fetters, Lewis J.; McIntyre, D.

doi:10.1021/ma60039a024

Cited by 56 publications

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“…Earlier, Slagowski et al 9 have reported that the molecular weight of the original polymer (M w = 4.4 × 10 7 ) had been decreased to 1.9 × 10 7 . In this connection, we prepared a linear poly(St) of ultrahigh molecular weight (M w (LS) = 8.1×10 6 ) by the emulsion polymerization and then, the poly(St) was subjected to SEC-MALLS measurement to give M w (SEC-MALLS)/M w (LS) value of 0.37.…”

Section: Resultsmentioning

confidence: 99%

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Degradation of Ultrahigh Molecular Weight Poly(styrene-co-m-divinylbenzene)s as Network-Polymer Precursors in SEC Columns

Matsumoto

Aota

2002

Polym J

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KEY WORDSDegradation / SEC Column / Styrene / m-Divinylbenzene / Ultrahigh Molecular Weight / Network-Polymer Precursor / As an extension of our continuing studies concerned with the mechanistic discussion of the three-dimensional network formation in the freeradical polymerization and copolymerization of multivinyl compounds, 1 the preceding article 2 dealt with the crosslinking copolymerization of styrene (St) with m-divinylbenzene (m-DVB) as a most typical monovinyl/divinyl system. Thus, the reasons for the greatly delayed gelation from Flory-Stockmayer gelation theory (FS theory) 3 have been discussed extensively in order to clarify the crosslinking polymerization mechanism of multivinyl compounds. 1 The actual gel point should be close to the theoretical one if the experiment were done under the polymerization conditions in which the polymer concentration, at the theoretical gel point, would be high enough to reduce the significance of a thermodynamic excluded volume effect as a primary factor and, furthermore, the intramolecular crosslinking preceded by the intermolecular crosslinking could be suppressed. Our interpretations are verified for monomethacrylate/dimethacrylate, 4, 5 monoacrylate/diacrylate, 6 and St/m-DVB 2 copolymerizations, in which the results obtained are discussed in terms of ideal network formation according to FS theory.In a series of these investigations, the detailed pursuit of the variation of molecular-weight distribution (MWD) curves with conversion is inevitable for a full understanding of crosslinking polymerization because the MWD curves should rapidly broaden towards a higher molecular weight side with conversion as a result of exclusive occurrence of intermolecular crosslinking reaction leading to ideal network formation. 3,7,8 Here it is worthy to note that a size-exclusion chromatography (SEC) is commonly used to determine † To whom correspondence should be addressed. the molecular weight and the MWD of resulting prepolymers. However, as a technique it is not always applicable to our crosslinking polymerization systems because the structure of prepolymer changes from a linear to a branched form with progressing polymerization and, moreover, the content of ring or loop structure introduced into the linear portion or primary chain and the content of multiple crosslink or network structure in the branched form depend on the polymerization conditions. On the other hand, SEC equipped with a multiangle laser light scattering (MALLS) device (SEC-MALLS) is expected to be a very useful and efficient tool in characterizing our prepolymers because the use of MALLS, as an absolute detector, enables the molecular weight and MWD to be determined directly without any calibration. 5 During the progress of our investigation, we noticed that the degradation of poly(St-co-m-DVB) prepolymer of ultrahigh molecular weight obtained at the conversion close to the gel point occurred significantly in SEC columns. That is, the molecular weights determined by both SEC-MALLS and light scattering (LS) me...

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Section: Resultsmentioning

confidence: 99%

“…[9][10][11] Barth et al 11 have reviewed the polymer shear degradation in SEC and guidelines involving operational parameters are presented. Thus, high molecular weight polymers are fairly sensitive to shear forces which can lead to chain scission.…”

Section: Introductionmentioning

confidence: 99%

Degradation of Ultrahigh Molecular Weight Poly(styrene-co-m-divinylbenzene)s as Network-Polymer Precursors in SEC Columns

Matsumoto

Aota

2002

Polym J

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“…It is known that macromolecules may degrade during the SEC separation due to the shear degradation in the column packing and in the frits. [9,[13][14][15]22,[24][25][26] Moreover, the intensive shear degradation in SEC is superimposed with the thermo-oxidative degradation of the macromolecules during the dissolution of the polymer sample. On the contrary, the shear degradation of macromolecules through AF4 separation is negligible.…”

Section: Resultsmentioning

confidence: 99%

“…The larger chains are more sensitive towards the shear forces than the smaller ones. [9,[13][14][15]22,[24][25][26] The destruction of the very large macromolecules in the columns leads to the formation of polymer chains with lower molar masses as degradation products. In HT-SEC these fragments will be detected, which leads to a broadening of the distribution in the low molar mass direction.…”

Section: Resultsmentioning

confidence: 99%

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Visualization of Thermo‐Oxidative Degradation of Polyolefins in Solution Using HT‐SEC and HT‐AF4‐MALS

Otte

Pasch

Brüll³

et al. 2011

Macro Chemistry & Physics

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The molar mass distributions of high‐molar‐mass PE and PP were characterized using HT‐AF4 and HT‐SEC in combination with IR and MALS detection. Calculated molar mass distributions, average molar masses and radii of gyration were compared. It was found that HT‐AF4 can detect the real extent of thermo‐oxidative degradation during dissolution. HT‐SEC is affected by shear and thermo‐oxidative degradation while in HT‐AF4 no shear stress exists. As a consequence, the molar mass averages obtained from HT‐SEC are pronouncedly lower as obtained from HT‐AF4. In addition, branched polyolefins cannot be correctly characterized by SEC‐MALS due to abnormal co‐elution effects. HT‐AF4 is therefore the method of choice for studying the thermo‐oxidative degradation of macromolecules with high molar masses. magnified image

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Experimental Variables and Techniques

Striegel¹,

Yau²,

Kirkland³

et al. 2009

Modern Size‐Exclusion Liquid Chromatography

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Upper Molecular Weight Limit for the Characterization of Polystyrene in Gel Permeation Chromatography

Cited by 56 publications

References 0 publications

Degradation of Ultrahigh Molecular Weight Poly(styrene-co-m-divinylbenzene)s as Network-Polymer Precursors in SEC Columns

Degradation of Ultrahigh Molecular Weight Poly(styrene-co-m-divinylbenzene)s as Network-Polymer Precursors in SEC Columns

Visualization of Thermo‐Oxidative Degradation of Polyolefins in Solution Using HT‐SEC and HT‐AF4‐MALS

Experimental Variables and Techniques

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