Direct imaging and elemental mapping of microgels in natural rubber particles

Rippel, Márcia Maria; Leite, Carlos A. P.; Lee, Lay-Theng; Galembeck, Fernando

doi:10.1007/s00396-004-1187-z

Cited by 44 publications

(32 citation statements)

References 15 publications

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“…Interestingly, the crosslink density of a macrogel exponentially increases with its protein concentration (R 2 = 0.967). Several studies have already suggested that proteins are partly responsible for the presence of macrogel in NR samples [14,21]. Our results showed that proteins play a major role in the structuring of a macrogel, and seem to be involved in the majority of crosslinks.…”

Section: 4supporting

confidence: 64%

“…Its exceptional properties are attributed to the stereoregularity of the polyisoprene chain (high cis-1,4 content), high polyisoprene molar masses [6][7][8], but also to the presence of a gel phase [9,10]. This gel phase is composed of an insoluble fraction called 'macrogel' [11,12], and of microaggregates dispersed in the soluble fraction, called 'microgel' [13,14] (Figure 1). Some non-isoprene compounds of NR, such as lipids (1.5-4% w/w) [4,[15][16][17], proteins (1-3.5% w/w) [4,[17][18][19], and minerals (0.2% w/w) [4,20], are assumed to be responsible for the existence of this gel phase.…”

Section: Introductionmentioning

confidence: 99%

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Characterisation of macrogel composition from industrial natural rubber samples: Influence of proteins on the macrogel crosslink density

Rolère¹,

Bottier²,

Vaysse³

et al. 2016

Express Polym. Lett.

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Abstract. The insoluble (macrogel) and soluble fractions of 11 commercial natural rubber (NR) samples (Technically specified rubber) were separated. Nitrogen titrations and lipid extractions enabled a quantitative assessment of the proteins and extractable lipids in each fraction. Swelling was measured in tetrahydrofuran in order to evaluate the crosslink density (M c -1 ) of each macrogel. While the soluble fraction had a high lipid concentration, the majority of non-isoprene compounds of the macrogel were found to be proteins, which accounted for 4.6 to 50.8% (w/w) of the macrogel. Indeed, the macrogels contained less than 0.5% (w/w) extractable lipids. However, our results showed that the soluble fraction contained large quantities of proteins (16-66% of the nitrogen content of the raw NR sample), probably structuring microaggregates. An exponential correlation (R 2 > 0.96) was found between the crosslink density and the protein concentration of macrogel, suggesting that proteins are involved in the majority of crosslinks in macrogel.

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Section: 4supporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Characterisation of macrogel composition from industrial natural rubber samples: Influence of proteins on the macrogel crosslink density

Rolère¹,

Bottier²,

Vaysse³

et al. 2016

Express Polym. Lett.

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“…A number of microchemical complexities was observed and the most remarkable is the clear association between sites bearing calcium ions and the ability to form gel, showing that these ions have a cross-linking role in the natural rubber. [17][18][19] Scanning probe microscopy has also yielded a wealth of information on colloidal polymers and it has a great advantage over electron microscopy that is the possibility to examine colloidal polymers under various environmental conditions. In a previous report from this group, polymer swelling under water was observed, showing that particle swelling is highly anisotropic and providing a visualization of film failure due to swelling pressure.…”

Section: Resultsmentioning

confidence: 99%

Morphology and Microchemistry of Colloidal Polymers

Galembeck

Valadares

Bragança

et al. 2006

Macromolecular Symposia

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Summary: Colloidal polymers are highly versatile due to the variety of properties and functions that can be created by changing monomer composition, surfactant, initiator and reaction protocol. Microchemical and morphological observation of the particles and particle aggregates as well as films and monoliths made with them is allowing us to understand the connections between nanosized structural features and macroscopic properties and this is essential for the creation of valuable new polymer materials. Electron spectroscopy imaging (ESI) in the transmission electron microscope (TEM) uses electron energy loss spectroscopy (EELS) to provide a wealth of information on particle constituents and their topological distribution, allowing a number of correlations with the polymer mechanical, thermal, optical and electrical properties. On the other hand, scanning probe microscopy (SPM) techniques allow direct measurement of particle and film properties such as adhesion, stiffness, electrostatic potential as well as rheology information with high spatial resolution, down to 10-20 nm and under many different experimental conditions. Information from the joint use of these techniques is revealing a wealth of nanostructures within colloidal polymers requiring a revision of many preconceived ideas on these materials.

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“…The serum phase contains different types of compounds, including carbohydrates, several proteins, amino acids and enzymes. Finally, the bottom fraction contains a high portion of monomers and metal ions [19,20].…”

Section: Introductionmentioning

confidence: 99%