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Evelyne Van Ruymbeke

Bio: Evelyne Van Ruymbeke is an academic researcher from Université catholique de Louvain. The author has contributed to research in topics: Reptation & Supramolecular polymers. The author has an hindex of 21, co-authored 63 publications receiving 1343 citations. Previous affiliations of Evelyne Van Ruymbeke include The Catholic University of America & University of Crete.


Papers
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Journal ArticleDOI
14 Jun 2006-Polymer
TL;DR: In this paper, the authors evaluate and compare all major published methods for the experimental determination of the plateau modulus for monodisperse as well as polydisperse polymers with linear architecture.

286 citations

Journal ArticleDOI
TL;DR: In this paper, a model system of pure poly(n-butyl acrylate), PnBA, homopolymer, copolymers with different number of hydrogen bonding groups is presented.
Abstract: Supramolecular polymers are used in many applications such as adhesives, coatings, cosmetics, and printing. Characterizing the dynamics of such polymers is essential for tailoring user defined properties in products and applications. We present both linear and nonlinear rheological results for a model system of pure poly(n-butyl acrylate), PnBA, homopolymer and four PnBA–poly(acrylic acid), PnBA–PAA, copolymers with different number of AA side groups. The copolymers are synthesized via hydrolysis of the pure PnBA homopolymer. Therefore, all polymers studied have the same backbone length. The number of AA side groups (hydrogen-bonding groups) after hydrolysis is determined from NMR measurements. We show that using the theoretical dependency of modulus and reptation time on the packing length, we can account for the changes in linear viscoelasticity due to transformation of nBA side groups to AA along the backbone. Assuming superposition holds and subtracting out the linear chain rheology from LVE, the hydr...

102 citations

Journal ArticleDOI
TL;DR: In this paper, the tube-based time marching algorithm was extended to entangled associative polymers with sticky side groups, with special emphasis on the effect of hindered fluctuations, besides sticky Rouse and sticky reptation.
Abstract: The design and effective application of supramolecular transient polymer networks based on the assembly of entangled polymer building blocks requires not only precise description of relaxation mechanisms of the chain segments but also inclusion of the kinetics of reversible formation and breakage of reversible supramolecular interactions. In this work we extend the tube-based time marching algorithm to the entangled associative polymers with sticky side groups, with special emphasis on the effect of hindered fluctuations, besides sticky Rouse and sticky reptation. Two different approaches are introduced for inclusion of hindered fluctuations comprising fluctuations with extra penalty for deeper segments and stepwise fluctuations by extra friction. It is shown that there is a transition zone in dynamic moduli between the characteristic lifetime of the stickers and emergence of the final relaxation slopes, which can be characterized by almost parallel drop of loss and storage moduli with slope of 0.5 that c...

97 citations

Journal ArticleDOI
TL;DR: Of all the different fibrin matrix concentrations tested, F50/T50 emerged as the combination of choice in terms of ultrastructure and rigidity, most closely resembling human ovarian cortex.
Abstract: The aim of this study is to optimize fibrin matrix composition in order to mimic human ovarian tissue architecture for human ovarian follicle encapsulation and grafting. Ultrastructure of fresh human ovarian cortex in age-related women (n = 3) and different fibrin formulations (F12.5/T1, F30/T50, F50/T50, F75/T75), rheology of fibrin matrices and histology of isolated and encapsulated human ovarian follicles in these matrices. Fresh human ovarian cortex showed a highly fibrous and structurally inhomogeneous architecture in three age-related patients, but the mean ± SD of fiber thickness (61.3 to 72.4 nm) was comparable between patients. When the fiber thickness of four different fibrin formulations was compared with human ovarian cortex, F50/T50 and F75/T75 showed similar fiber diameters to native tissue, while F12.5/T1 was significantly different (p value < 0.01). In addition, increased concentrations of fibrin exhibited enhanced storage modulus with F50/T50, resembling physiological ovarian rigidity. Excluding F12.5/T1 from further analysis, only three remaining fibrin matrices (F30/T50, F50/T50, F75/T75) were histologically investigated. For this, frozen-thawed fragments of human ovarian tissue collected from 22 patients were used to isolate ovarian follicles and encapsulate them in the three fibrin formulations. All three yielded similar follicle recovery and loss rates soon after encapsulation. Therefore, based on fiber thickness, porosity, and rigidity, we selected F50/T50 as the fibrin formulation that best mimics native tissue. Of all the different fibrin matrix concentrations tested, F50/T50 emerged as the combination of choice in terms of ultrastructure and rigidity, most closely resembling human ovarian cortex.

67 citations

Journal ArticleDOI
TL;DR: In this article, the linear viscoelastic properties of a series of polystyrene melts with pom-pom architecture consisting of backbones ranging from marginally to well-entangled (of molecular weight Mb), endgrafted with q unentangled branches (Mbr) per backbone end.
Abstract: We measured the linear viscoelastic properties of a series of polystyrene melts with pom-pom architecture consisting of backbones ranging from marginally to well-entangled (of molecular weight Mb), endgrafted with q unentangled branches (Mbr) per backbone end. In this case, the branches relax very fast and act primarily as solvents for the backbone. Using a time-marching tube-based model, we showed that, in such a case only, the pom-pom polymer is equivalent to a blend of long (ML Mb + 2Mbr) and short (MS Mbr) linear chains with respective proportion (Mb + 2Mbr)/2(q - 1)Mbr.

60 citations


Cited by
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01 Dec 1991
TL;DR: In this article, self-assembly is defined as the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds.
Abstract: Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

2,591 citations

Journal ArticleDOI
TL;DR: The Engineering and Physical Sciences Research Council and the European Research Council are acknowledged for financial support.
Abstract: The Engineering and Physical Sciences Research Council and the European Research Council are acknowledged for financial support.

801 citations

Journal ArticleDOI
TL;DR: Variable-temperature SAXS analysis shows that the healable polymeric blend has a nanophase-separated morphology and that the X-ray contrast between the two types of domain increases with increasing temperature, a feature that is repeatable over several heating and cooling cycles.
Abstract: An elastomeric, healable, supramolecular polymer blend comprising a chain-folding polyimide and a telechelic polyurethane with pyrenyl end groups is compatibilized by aromatic π−π stacking between the π-electron-deficient diimide groups and the π-electron-rich pyrenyl units. This interpolymer interaction is the key to forming a tough, healable, elastomeric material. Variable-temperature FTIR analysis of the bulk material also conclusively demonstrates the presence of hydrogen bonding, which complements the π−π stacking interactions. Variable-temperature SAXS analysis shows that the healable polymeric blend has a nanophase-separated morphology and that the X-ray contrast between the two types of domain increases with increasing temperature, a feature that is repeatable over several heating and cooling cycles. A fractured sample of this material reproducibly regains more than 95% of the tensile modulus, 91% of the elongation to break, and 77% of the modulus of toughness of the pristine material.

733 citations

Journal ArticleDOI
TL;DR: Using properly purified high-molar-mass ring polymers, it is demonstrated that these materials exhibit self-similar dynamics, yielding a power-law stress relaxation, however, trace amounts of linear chains at a concentration almost two decades below their overlap cause an enhanced mechanical response.
Abstract: After many years of intense research, most aspects of the motion of entangled polymers have been understood. Long linear and branched polymers have a characteristic entanglement plateau and their stress relaxes by chain reptation or branch retraction, respectively. In both mechanisms, the presence of chain ends is essential. But how do entangled polymers without ends relax their stress? Using properly purified high-molar-mass ring polymers, we demonstrate that these materials exhibit self-similar dynamics, yielding a power-law stress relaxation. However, trace amounts of linear chains at a concentration almost two decades below their overlap cause an enhanced mechanical response. An entanglement plateau is recovered at higher concentrations of linear chains. These results constitute an important step towards solving an outstanding problem of polymer science and are useful for manipulating properties of materials ranging from DNA to polycarbonate. They also provide possible directions for tuning the rheology of entangled polymers.

454 citations

Journal Article
TL;DR: In this paper, the authors explore recent advances in the design and engineering of materials wholly or principally constructed from peptides, and focus on materials that are able to respond to changes in their environment (pH, ionic strength, temperature, light, oxidation/reduction state, presence of small molecules or the catalytic activity of enzymes) by altering their macromolecular structure.
Abstract: This article explores recent advances in the design and engineering of materials wholly or principally constructed from peptides. We focus on materials that are able to respond to changes in their environment (pH, ionic strength, temperature, light, oxidation/reduction state, presence of small molecules or the catalytic activity of enzymes) by altering their macromolecular structure. Such peptide-based responsive biomaterials have exciting prospects for a variety of biomedical and bionanotechnology applications in drug delivery, bio-sensing and regenerative medicine.

452 citations