Some observations on the colloidal behaviour of block copolymers

Lally, T.P.; Price, Colin

doi:10.1016/0032-3861(74)90132-3

Cited by 40 publications

(4 citation statements)

References 6 publications

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“…This is typical for d-spacings of hexagonally packed cylinders with sufficiently long-range order, 14,22 and the results are consistent with previous studies by Keller et al 23,24 and Lewis and Price. [25][26][27] For the SBS-4 sample, it seems that there is a scattering peak at a relative q value of 8 instead of 7, and the reason for this is not yet clear. No conclusions regarding the actual domain shapes can be made by this analysis.…”

Section: Saxs Studiesmentioning

confidence: 99%

A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

Natansohn

Singh

et al. 1999

Macromolecules

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The complementary techniques of solid-state NMR and small-angle X-ray scattering (SAXS) have been used to determine the microdomain structures of a series of commercial poly(styrene-b-butadiene-b-styrene) triblock copolymers with different molecular weights. The relative locations of multiple scattering peaks, indirect transform, and Porod analysis have been used to determine the morphology and the sizes of various domains as well as the interfacial thickness between them. Solid-state NMR of 1H spin diffusion measurements was also used to estimate the microdomain structure parameters by simulating the spin diffusion processes with a model that considers the effects of 1H spin−lattice relaxation. The interfacial thickness, 2 nm for all five materials, and the interdomain distances, ranging from 30 to 42 nm, from NMR agree well with results from SAXS techniques. There are some discrepancies for some of samples regarding the domain sizes of dispersed polystyrene phases obtained from the above two techniques. These discrepancies may be mainly caused by the limited quality of the fitting procedure using indirect transform methods.

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Section: Saxs Studiesmentioning

confidence: 99%

A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

Natansohn

Singh

et al. 1999

Macromolecules

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“…2,[17][18][19] Of particular relevance to the present study is the worm morphology, which has been recognized for at least three decades. 20,21 Seminal work in this area includes that by Bates and co-workers 4,22,23 and also by Discher's group. 24,25 For example, the latter team demonstrated that poly(ethylene oxide)-based diblock copolymer worms can avoid endocytosis by mammalian cells, which leads to relatively long circulation times and hence new opportunities for drug delivery.…”

Section: Introductionmentioning

confidence: 99%

Aqueous worm gels can be reconstituted from freeze-dried diblock copolymer powder

2014

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Worm-like diblock copolymer nanoparticles comprising poly(glycerol monomethacrylate) (PGMA) as a stabilizer block and poly(2-hydroxypropyl methacrylate) (PHPMA) as a core-forming block were readily synthesized at 10% w/w solids via aqueous dispersion polymerization at 70 °C using Reversible Addition-Fragmentation chain Transfer (RAFT) chemistry. On cooling to 20 °C, soft transparent free-standing gels are formed due to multiple inter-worm interactions. These aqueous PGMA-PHPMA diblock copolymer worms were freeze-dried, then redispersed in water with cooling to 3-5 °C before warming up to 20 °C; this protocol ensures molecular dissolution of the copolymer chains, which aids formation of a transparent aqueous gel. Rheology, SAXS and TEM studies confirm that such reconstituted gels comprise formed PGMA-PHPMA copolymer worms and they possess essentially the same physical properties determined for the original worm gels prior to freeze-drying. Such worm gel reconstitution is expected to be highly beneficial in the context of various biomedical applications, since it enables worm gels to be readily prepared using a wide range of cell growth media as the continuous aqueous phase.

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“…The phenomenon of micellization in block copolymer solutions has been a subject of considerable interest for over 40 years. , A great deal is now known about the various self-assembled structures that can be formed and the factors that influence the choice of structure and the location of the critical micelle concentration (cmc) and critical micelle temperature (cmt). An interesting phenomenon associated with the micellization process, and especially in the context of the cmt, has been termed “anomalous micellization”. ,− The details of this phenomenon do vary from system to system, and the term has not been universally adopted, but the general features of anomalous micellization may be summarized as follows. , Some dilute copolymer solutions show three regimes of behavior as a function of temperature: spherical micelles, single chains, and an intermediate anomalous regime. In this intermediate regime, the intensity of scattered light is very high and shows a pronounced angular dependence; in some cases the solution becomes visibly turbid.…”

Section: Introductionmentioning

confidence: 99%

Origins of Anomalous Micellization in Diblock Copolymer Solutions

et al. 2003

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The phenomenon of "anomalous" micellization is investigated in dilute solutions of two nearly symmetric poly(styrene-b-isoprene) diblock copolymers, via dynamic light scattering. In two polystyrene-selective solvents, diethyl phthalate and dimethyl phthalate, the critical micelle temperatures (cmt) are clearly determined by rather abrupt increases in the hydrodynamic radius and scattered intensity upon cooling; this corresponds to "normal" micellization. In contrast, for the same polymers dissolved in two polyisopreneselective solvents, tetradecane and squalane, anomalous micellization was consistently observed: the hydrodynamic radius exceeded 1000 Å and the intensity was unusually large, over a modest temperature interval just above the cmt. We propose that anomalous micellization is due to the incipient phase separation of small amounts of polystyrene homopolymer, resulting from incomplete crossover during the sequential anionic polymerization of styrene and isoprene. In one sample, the presence of homopolymer (ca. 1 wt % of copolymer) was confirmed by chromatography, and removal of this impurity eliminated the anomalous micellization. Addition of similar amounts of polyisoprene homopolymer to the same sample induced anomalous micellization in the polystyrene-selective solvents, with the onset of the effect corresponding to the cloud point for the polyisoprene homopolymer. These observations support the proposed hypothesis; the extent to which this hypothesis may extend to previous reports of anomalous micellization is discussed. LA0268808

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Some observations on the colloidal behaviour of block copolymers

Cited by 40 publications

References 6 publications

A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

A Comparative Study Using Small-Angle X-ray Scattering and Solid-State NMR of Microdomain Structures in Poly(styrene−butadiene−styrene) Triblock Copolymers

Aqueous worm gels can be reconstituted from freeze-dried diblock copolymer powder

Origins of Anomalous Micellization in Diblock Copolymer Solutions

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