NMR Study of the Morphology of Polystyrene Linear/Microgel Blends

McGrath, K. J.; Roland, C. M.; Antonietti, Markus

doi:10.1021/ma000951x

Cited by 12 publications

(18 citation statements)

References 69 publications

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“…15 Homogeneity could be achieved once the chains grafted to the microgels or once the PB-blocks in the corona of the micelles were equal or larger in molecular weight than the molecular weight of the respective hosting matrix chains. This result is closely related to the observation made by Antonietti et al, 12 which indicates a penetration of matrix chains into the microgels, once the matrix chains get smaller than the mesh size in the microgels. Schartl et al 16 successively investigated the rheological behavior of selected blends marked by the feature that the coil size of the matrix material kept below the entanglement regime.…”

Section: ■ Introductionsupporting

confidence: 89%

“…With the detailed set of reference data presented above, proper analysis of SANS data from the blend is now accessible. To this end, blends were prepared according to three different methods: evaporation of chloroform (SE), precipitation of a THF solution in isohexane (RP) and freeze-drying of the benzene solution (FD). ,, The first method directly resulted in a thin foil. In the case of the second and third method thin foils were obtained after mold injection with a heatable press.…”

Section: Resultsmentioning

confidence: 99%

“…Antonietti et al 12 have prepared blends from cross-linked polystyrene microgels with linear polystyrene (PS) chains. Since both components were chemically identical, the blends could easily be prepared by mixing the two component solutions and freeze-drying the mixed solution (FD method).…”

Section: ■ Introductionmentioning

confidence: 99%

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Morphology of Blends with Cross-Linked PMMA Microgels and Linear PMMA Chains

et al. 2013

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The present work investigates PMMA colloids in a polymer matrix of linear chains as a simple and suitable system for complex nanocomposites. The investigation was based on SANS experiments, which were enabled by the use of deuterated colloids immersed in a matrix of linear hydrogenated chains. Cross-linked deuterated PMMA-colloids were synthesized with two different sizes (70 and 140 nm) by means of the surfactant-free emulsion polymerization method and the swelling behavior adjusted by varying the amount of added cross-linker (1.5 and 15.0 mol-%) at each size respectively. Colloid−polymer blends were prepared from colloid−polymer solutions. SANS experiments on these blends consistently revealed that colloids with a low cross-linking density could be homogeneously distributed throughout the matrix of linear chains. Fits with model form factors indicated the structure of fuzzy spheres for these molecularly dispersed microgels, which are slightly swollen with respect to their size and shape in H 2 O. Contrary to this, colloids with a high cross-linking density form aggregates in the blends. Despite this aggregation, we succeeded to unravel the shape and the size of single colloids by preparation of colloid− polymer blends where the colloid component is a binary mixture of deuterated and hydrogenated colloids both with a high crosslinking density. SANS on the latter blends suggested a core−shell particle in a lattice cell of an aggregate.

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Section: ■ Introductionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

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Morphology of Blends with Cross-Linked PMMA Microgels and Linear PMMA Chains

et al. 2013

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“…50 To establish similar powerlaw dependence for our samples is difficult, since the variation of branch lengths for the same branch density in these polymers is limited. To get an idea about how the dimensions of HBPS molecules compare to that of linear PS and polystyrene microgels in the study of McGrath et al, 51 experimentally obtained radii of gyration of the three HBPS systems are shown in Figure 6 when plotted against weight-average molecular weight. When data for 10K-and 20K-HBPS are added in Figure 6, it appears that the dimensions of these HBPS are roughly twice as big as the microgels but about three times smaller than linear molecules of equal molecular weight.…”

Section: Resultsmentioning

confidence: 99%

Role of Architecture on the Conformation, Rheology, and Orientation Behavior of Linear, Star, and Hyperbranched Polymer Melts. 1. Synthesis and Molecular Characterization

Kharchenko¹,

Kannan²,

Cernohous³

et al. 2002

Macromolecules

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In the preceding publication, we showed that the hyperbranched polystyrenes (HBPS) synthesized as part of this study may be viewed as starlike molecules with a high branch density, which are either unentangled or weakly entangled. In this paper, the role of architecture, especially the branch density, on the rheological and orientation behavior is investigated using simultaneous, quantitative stress and flow birefringence measurements in the melt state. Linear PS and eight-arm symmetric PS stars follow the stress-optical rule (SOR) over a wide dynamic range, with the stress-optical coefficient (C) governed by the arm molecular weight. When the branch density is "moderate" (greater than ∼20 arms), there is only a hint of nonterminal behavior in the viscoelastic moduli, while the C drops by 30% compared to a star with eight arms of comparable length. When the branch density is "high" (∼50 arms), and the arms are unentangled, the nonterminal behavior in G* is clearly apparent, and there is a dramatic breakdown in the stress-optical rule in these homopolymer melts. The quantitative birefringence measurements suggest that the "excess" birefringence may be due to the "form" contributions from the core-shell structure. Such a structure may be formed by the preferential radial stretching of the chain segments near the core, as suggested by other studies on hyperstars. For comparable chain density, the core would be bigger than the shell when the arm length is smaller. Therefore, the 5K-HBPS exhibits a more severe breakdown compared to the 10K-HBPS.

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“…The surfactant, the product of an alkyldiethanolamine and a metal ion (copper), was very effective for this purpose. The researchers isolated and characterized the polystyrene-diisopropenylbenzene (DIB) microgels via NMR, rheology, small-angle neutron scattering, dynamic mechanical analysis, and SLS and DLS techniques . The Larpent group has similarly used a batch microemulsion polymerization to yield 10–12 nm diameter PNPs.…”

Section: Introductionmentioning

confidence: 99%

Determination of Particle Size Distributions, Molecular Weight Distributions, Swelling, Conformation, and Morphology of Dilute Suspensions of Cross-Linked Polymeric Nanoparticles via Size-Exclusion Chromatography/Differential Viscometry

et al. 2014

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Size-exclusion chromatography (SEC), coupled with differential viscometry detection (SEC/DV), is applied to the dilute suspension characterization of solvent-swollen cross-linked polymeric nanoparticles (PNPs). Cross-linked, unimolecular polymeric nanoparticles in the 5−50 nm weight-average diameter (d w ) range were prepared by batch and semibatch microemulsion polymerization techniques and isolated. SEC and SEC/DV characterization techniques yield, based on the principle of universal calibration, a wealth of information regarding the structural attributes of PNPs, including apparent and absolute molecular weight distributions, apparent and absolute molecular weight averages, peak and weightaverage particle diameters, particle size distributions in both the solvent-swollen and solvent-free states, particle conformation (shape), and an estimate of the volumetric swell factor. These structural parameters are critical to understanding PNP performance, and all are obtained in a single rapid chromatographic experiment, when conducted under conditions where universal calibration applies. Particle sizes determined under such conditions are in excellent agreement with those obtained by dynamic light scattering, transmission electron microscopy, hydrodynamic chromatography, and SEC/static light scattering (SEC/SLS). In addition, Mark−Houwink exponents of approximately zero were found across the molecular weight and size distribution of many of these tightly cross-linked PNPs, which is consistent with a spherical particle conformation in these dilute suspensions. The SEC/DV methods are especially valuable to characterize the diameter, volume swell factor, and suspension conformation of small (4−5 nm d w ) PNPs.

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NMR Study of the Morphology of Polystyrene Linear/Microgel Blends

Cited by 12 publications

References 69 publications

Morphology of Blends with Cross-Linked PMMA Microgels and Linear PMMA Chains

Morphology of Blends with Cross-Linked PMMA Microgels and Linear PMMA Chains

Role of Architecture on the Conformation, Rheology, and Orientation Behavior of Linear, Star, and Hyperbranched Polymer Melts. 1. Synthesis and Molecular Characterization

Determination of Particle Size Distributions, Molecular Weight Distributions, Swelling, Conformation, and Morphology of Dilute Suspensions of Cross-Linked Polymeric Nanoparticles via Size-Exclusion Chromatography/Differential Viscometry

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