Nanostructure Formation via Association of Tectons in Amorphous Polymer Matrices

Fuchs, Katharina; Bauer, Thorsten; Thomann, Ralf; Wang, Chun; Friedrich, Christian; Mülhaupt, Rolf

doi:10.1021/ma9912406

Cited by 16 publications

(32 citation statements)

References 21 publications

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“…Previous studies have shown that micro-and nanosized pores can be formed by VIPS in thin films. 64,65 This principle was applied to produce the BNTHP membranes in our study. Various process parameters (i.e., solvent volatility, initial polymer concentration, and relative humidity, etc.)…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Cellular Layer-by-Layer Coculture Platform Using Biodegradable, Nanoarchitectured Membranes for Stem Cell Therapy

et al. 2017

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Stem cells are regulated in vivo through interactions with the surrounding microenvironments in a three-dimensional (3D) manner. A coculture of stem cells with desired cell types, which recapitulates the complex in vivo cell−cell communications, has been reported as an effective method to direct stem cell differentiation into specific lineage. However, conventional bilayer coculture systems employ membranes of microscale thickness and low porosity, which limit interaction between cocultured cells for efficient stem cell differentiation. Furthermore, conventional coculture systems require cell-impairing enzyme treatment to harvest the cells from the membranes. Here, we developed a cellular layer-by-layer (cLbL) coculture platform using biodegradable, nanothin, highly porous (BNTHP) membranes. Equipped with more porous and thinner membranes, the cLbL coculture platform better mimicked the in vivo 3D microenvironment and promoted cellular cross-talks between cocultured cells which occurred in nanoscale, resulting in more efficient stem cell differentiation compared to the conventional bilayer coculture systems. Furthermore, biodegradibility, biocompatibility, and highly flexibility of BNTHP membranes enabled conversion of the cell-attached membranes into implantable 3D cell constructs, thus avoiding harmful enzymatic harvesting of the cells. The cLbL platform may be an effective method to induce stem cell differentiation and facilitate cell implantation for stem cell therapy.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Cellular Layer-by-Layer Coculture Platform Using Biodegradable, Nanoarchitectured Membranes for Stem Cell Therapy

et al. 2017

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“…This behavior is similar to what we already observed for PS compounds. 9 The only difference is the absolute value of the transition temperature: The formation and dissolution temperatures of the assemblies are significantly lower in PS compared with PP.…”

Section: Resultsmentioning

confidence: 99%

“…From the literature 8,9 we know that equimolar mixtures of OT crystallize and melt at temperatures around 170 and 190 °C, respectively. These characteristic transition temperatures and the morphology of the samples are strongly influenced by the presence of a solvent (here polymer; for details see Guenet 16 and Terech and Weiss 2 ).…”

Section: Discussionmentioning

confidence: 99%

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Linear and Nonlinear Rheological Properties of Self-Assembling Tectons in Polypropylene Matrices

et al. 2003

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The supramolecular assembling of small, equimolar amounts of octyl-substituted complementary tectons based upon barbituric acid (BA) and 2,4,6-triaminopyrimidine (TP) in an isotactic and, particularly, in an atactic polypropylene matrix was studied by means of dynamic-mechanical spectroscopy. Self-organization of these tectons within the matrix depends on temperature and concentration of tectons and leads to network-like behavior, which is accompanied by drastic changes of the melt rheology of these compounds in comparison to the pure matrix. In addition to external parameters such as temperature, the formation of a tecton network which sets in for a concentration of 2 wt % and higher is determined by the enthalpic interactions between matrix and tectons. It turned out that none of the thermorheological and viscoelastic properties of the compounds depend on tacticity. Strain-sweep experiments reveal the extreme shear sensitivity of the formed supramolecular structures. Moreover, these experiments show that in all samples a certain amount of tecton (approximately 1%) remains dissolved and thus constitutes an "effective matrix" in which the network formation occurs. An estimation of the critical deformation, which is on the order of magnitude of 10 -4 , was achieved by means of creep experiments.

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“…For example, “supramolecular polymers” display unique rheological properties due to the reversibility of the hydrogen-bonding interactions between mesogenic or polymeric components . Small molecule additives with hydrogen bonding groups, such as 1,3:2,4-dibenzylidenesorbitol or various substituted binary complexes of barbiturates and 2,4,6-triaminopyrimidines, spontaneously form three-dimensional continuous fibrillar networks in host polymers. − These networks, in both the melt and crystalline state, can produce measurable effects on the mechanical properties of the blends at low concentrations of the small molecule component (<3%).…”

Section: Introductionmentioning

confidence: 99%

Rheology and Morphology of Smectic Liquid Crystal/Polymer Blends

Yonezawa¹,

Martin²,

Macosko³

et al. 2004

Macromolecules

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Polymers are often blended with additives (e.g., polymers, clays) to produce composite materials having desirable physical properties that reflect synergy between the blend constituents. Though polymer blends with small-molecule nematic liquid crystal phases have been investigated (primarily for displays), related materials containing small-molecule smectic phases have not been reported. Guanidinium alkylbenzenesulfonates (GCnBS, where n is the number of carbons in the alkyl chain), which form stable smectic phases at elevated temperatures because of a robust two-dimensional hydrogen-bonding network of guanidinium ions and sulfonate moieties, were melt-blended with various polymers. Rheological characterization of the blends reveals a yielding behavior, characteristic of the pure GCnBS smectic phases, which becomes more pronounced with increasing GCnBS concentration. Two microstructuresone a continuous polymer phase embedded with GCnBS droplets and the other a continuous GCnBS phase with a discontinuous polymer phaseare observed, the latter at GCnBS concentrations as low as 2 wt %. The tendency of the blends to form a microstructure in which GCnBS is continuous requires the existence of a smectic phase (observed only for n ≥ 7) and is dependent on alkyl chain length and GCnBS concentration. Injection of molten blends containing smectic phases into a rectangular mold resulted in stratification of the rectangular composite plaque due to the formation of large two-dimensional crystalline lamellae upon cooling of the GCnBS smectic phase dispersed in the blend. This stratification, which can be attributed to large extensional stresses experienced by the blend during molding, depends on alkyl chain length, GCnBS concentration, and the magnitude of the stresses exerted on the molten blend. These results illustrate that smectic phases can promote unusual microstructures in polymer blends at very low concentrations, which may be useful in certain commercial applications.

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Nanostructure Formation via Association of Tectons in Amorphous Polymer Matrices

Cited by 16 publications

References 21 publications

Cellular Layer-by-Layer Coculture Platform Using Biodegradable, Nanoarchitectured Membranes for Stem Cell Therapy

Cellular Layer-by-Layer Coculture Platform Using Biodegradable, Nanoarchitectured Membranes for Stem Cell Therapy

Linear and Nonlinear Rheological Properties of Self-Assembling Tectons in Polypropylene Matrices

Rheology and Morphology of Smectic Liquid Crystal/Polymer Blends

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