Determination of the width of the domain boundaries in polymer two-phase systems by X-ray small-angle scattering

Siemann, U.; Ruland, W.

doi:10.1007/bf01451646

Cited by 56 publications

(40 citation statements)

References 25 publications

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“…Small deviations from a sharp boundary would indicate a significant deviation from Porod's law. 21 Therefore, we can conclude that the phase boundaries of the complexes are of the order of 1-2 These values are similar to the polymeric complexes of siloxane surfactants we investigated earlier. 23 The simplest complex structure, which is in agreement with these numbers, is a microphase-separated model constructed from a smaller ionic phase (polyelectrolyte plus ionic headgroups) and a larger nonionic phase (hydrophobic moieties).…”

Section: Resultssupporting

confidence: 62%

“…The main source of error in the range of validity covered by Porod's law is the scattering due to density fluctuations and the widths of the domain boundary. 21 The values of s 4 I(s), as shown in Figure 4, were found to be constant for a scattering vector in the range 0.4-0.8 nm -1 . This proves that the structures of the complexes are consistent with Porod's law.…”

Section: Resultsmentioning

confidence: 97%

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Polyethylenimine Complexes with Retinoic Acid: Structure, Release Profiles, and Nanoparticles

Thünemann

Beyermann

2000

Macromolecules

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In this paper we discuss the preparation of complexes formed by polyethylenimine (PEI) and retinoic acid. The molecular weights of the PEIs were 600, 2000, 25 000, and 750 000 g/mol. All complexes form smectic A-like structures whose orders decrease with increasing molecular weight. The complexes in the bulk material obey Porod's law. Macroscopically oriented multilayer films of the complexes were prepared in a single-step procedure by spin coating and were characterized by X-ray reflectivity. The release of retinoic acid from the films was investigated by FTIR and surface tension measurements. It was found that the release from the complexes with the high molecular weight PEIs is faster than that from the complexes with low molecular weight. Steric stabilized nanoparticles of the complexes were prepared with sizes ranging from 170 to 580 nm by using Poloxamer 188 as the dispersing agent in aqueous media. Their characterization was carried out using dynamic light scattering and atomic force microscopy. It was found that the particle sizes decreased with the increasing molecular weight of the PEIs. Further, the particle structure became more compact with the increasing molecular weight of the PEIs. The particles of the complexes with the lowest molecular weight were assumed to be doughnutshaped (toroids).

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Section: Resultssupporting

confidence: 62%

Section: Resultsmentioning

confidence: 97%

Polyethylenimine Complexes with Retinoic Acid: Structure, Release Profiles, and Nanoparticles

Thünemann

Beyermann

2000

Macromolecules

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“…In reality, there exist short range electron density fluctuations within each of the two phases, which lead to an additional background scattering, JH(s). There-(3) fore, similar to the procedures applied in earlier investigations [13,14], in the present work JFt(S) has been assumed to have a constant value ]~ not dependent on s. This value is obtained by variation of Jpt and dz in a process demanding Porod's law to be fulfilled in a maximal interval of s. The variational process is explained in more detail below. This leads to deviations from Porod's law, according to which, at large scattering angles, J(s) decreases proportionally to 1/s 3 .…”

Section: Theoretical Sectionmentioning

confidence: 91%

“…This is done in the present work by the (2) procedure developed by Ruland et al [11][12][13][14], briefly discussed in the following. In reality, there exist short range electron density fluctuations within each of the two phases, which lead to an additional background scattering, JH(s).…”

Section: Theoretical Sectionmentioning

confidence: 99%

Morphological changes in SBS block copolymers caused by oil extension as determined by absolute small angle x-ray scattering

Polizzi

Stribeck

Zachmann

et al. 1989

Colloid & Polymer Sci

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A series of SBS block copolymers diluted with different amounts (0-60 wt %) of three different kinds of oil were investigated: 1) lithene PM (a low molecular weight polybutadiene); 2) a paraffinic mineral oil with its electron density close to that of the polybutadiene (PB) phase; 3) a highly aromatic mineral oil with an electron density close to the polystyrene (PS) phase. All the oils seem to go into the polybutadiene matrix. Paraffinic oil and lithene form a homogeneous phase with PB; the aromatic oil at low concentrations mixes with the PB phase with a high level ofinhomogeneity, while at higher concentration partial phase separation occurs. In the undiluted polymer, styrene forms cylinders in hexagonal packing. The distance between cylinders (about 43 nm) is not significantly changed upon dilution up to 33 wt %. Previously proposed changes in the morphology of PS domains at larger oil contents can be related to observed changes in the long period, in the segment length distributions, and in the homogeneities of the phase (density fluctuations). The electron density difference obtained for pure SBS is lower than the theoretical one calculated from the densities of pure PS and pure PB. Dilution by paraffinic oil improves the phase separation.

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“…A systematic investigation of equilibrium and non-equilibrium effects was carried out by Shibayama et a1.34). Conflicting data are also published about the absolute thickness of the interfacial region 21, 36,38).…”

Section: Introductionmentioning

confidence: 99%

Block copolymers with controlled interphase width. Effects of interphase and composition on domain dimensions

Bühler¹,

Gronski²

1986

Makromol. Chem.

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Ultrathin osmium tetroxid stained sections of solution cast block copolymer films were studied by electron microscopy. Two morphological systems were prepared from diblock copolymers containing 80 wt.-Yo styrene and 20 wt.-Vo isoprene: Systems with asymmetric lamellar morphology cast from cyclohexane, a preferential solvent for PI; and spherical morphology of rubber spheres in a continuous PS matrix, cast from tetrachloromethane, a non-selective solvent. For the two morphologies the variation of domain dimensions was studied in dependence of molecular weight in the range from 70000 to 6OOOOO g/mol. Two types of block copolymers were investigated: Unmodified block copolymers and block copolymers containing 10 wt.-To of a random interblock between the pure polystyrene and polyisoprene blocks. For both kinds of morphologies the domain dimensions of the unmodified systems vary with Mn2'3 as predicted by Helfand's theory. In the modified block copolymers a much weaker increase with M , is found for both morphological systems. The results can be understood in terms of equilibrium domain dimensions controlled by an interfacial tension depending on both composition and sequence structure of the block copolymers.

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Determination of the width of the domain boundaries in polymer two-phase systems by X-ray small-angle scattering

Cited by 56 publications

References 25 publications

Polyethylenimine Complexes with Retinoic Acid: Structure, Release Profiles, and Nanoparticles

Polyethylenimine Complexes with Retinoic Acid: Structure, Release Profiles, and Nanoparticles

Morphological changes in SBS block copolymers caused by oil extension as determined by absolute small angle x-ray scattering

Block copolymers with controlled interphase width. Effects of interphase and composition on domain dimensions

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