Search results for "star polymer"
showing 9 items of 9 documents
Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length.
2010
Due to the low solubility of poly(glycolic acid) (PGA), its use is generally limited to the synthesis of random copolyesters with other hydroxy acids, such as lactic acid, or to applications that permit direct processing from the polymer melt. Insolubility is generally observed for PGA when the degree of polymerization exceeds 20. Here we present a strategy that allows the preparation of PGA-based multi-arm structures which significantly exceed the molecular weight of processable oligomeric linear PGA (<1000 g/mol). This was achieved by the use of a multifunctional hyperbranched polyglycerol (PG) macroinitiator and the tin(II)-2-ethylhexanoate catalyzed ring-opening polymerization of gly…
Dynamics of Dense Polymers: A Molecular Dynamics Approach
1988
The physics of polymeric materials[1, 2] is one of the most challenging problems in condensed matter physics today. It is a problem of great interest both from a fundamental viewpoint and for their various technical applications. In addition to theortical and experimental approaches, computer simulations[3–11] have played an important role in our present understanding of polymers. For static properties Monte Carlo methods have been widely used and give excellent results for static critical exponents. To investigate dynamic properties three different methods — Monte Carlo (MC)[3–7], molecular dynamics (MD)[8, 9] and Brownian dynamics methods[10] — have been used. Detailed microscopic dynamic…
Controlling the Interactions between Soft Colloids via Surface Adsorption
2013
By employing monomer-resolved computer simulations and analytical considerations based on polymer scaling theory, we analyze the conformations and interactions of multiarm star polymers strongly adsorbed on a smooth, two-dimensional plane. We find a stronger stretching of the arms as well as a stronger repulsive, effective interaction than in the three dimensional case. In particular, the star size scales with the number of arms $f$ as $\sim f^{1/4}$ and the effective interaction as $\sim f^{2}$, as opposed to $\sim f^{1/5}$ and $\sim f^{3/2}$, respectively, in three dimensions. Our results demonstrate the dramatic effect that geometric confinement can have on the effective interactions and…
Hyperbranched Polymers
2012
Life is branched! Statistically branched (=hyperbranched) polymers have become an important class of materials in modern chemistry. Not only due to straightforward synthetic approaches which were developed in the last decade but also due to the vast amount of available monomers, hyperbranched polymers have replaced perfect dendrimers in many areas and they will have an even higher impact in future. This chapter highlights classic and modern syntheses of hyperbranched polymers and their unique properties and presents their versatility in the macromolecular toolbox for the design of complex nonlinear architectures.
Scaling theory of star polymers and general polymer networks in bulk and semi-infinite good solvents
1988
Theorie d'echelle utilisant l'equivalence entre la fonction generatrice du nombre total de configuration et la fonction de correlation a plusieurs spins du modele de Heisenberg classique a n composantes dans la limite n→0
Third virial coefficient for 4-arm and 6-arm star polymers
2008
We discuss the computation of the third virial coefficient in polymer systems, focusing on an additional contribution absent in the case of monoatomic fluids. We determine the interpenetration ratio and several quantities that involve the third virial coefficient for star polymers with 4 and 6 arms in the good-solvent regime, in the limit of a large degree of polymerization.
Core‐shell nanoparticles with hyperbranched poly(arylene‐oxindole) interiors
2009
Opracowano synteze wysoce rozgalezionego poli(aryleno-oksyndolu) na drodze reakcji polimeryzacji pochodnej 5-bromoizatyny, a nastepnie modyfikacji terminalnych jednostek izatynowych. Tak przygotowany polimerowy rdzen, charakteryzujący sie stopniem rozgalezienia 100 %, byl substratem do rodnikowej polimeryzacji z przeniesieniem atomu (z ang. ATRP) w reakcji z akrylanem tert-butylu. Otrzymane kopolimery zawierające hydrofobowy rdzen i alkilowe lancuchy zakonczone wolnymi grupami karboksylowymi tworzą sferyczne nanocząstki. Przedstawiono wstepne wyniki badan dotyczących ich wlaściwości fizykochemicznych oraz potencjalnych zastosowan.
Electrostatically Driven Complexation of Liposomes with a Star-Shaped Polyelectrolyte to Low-Toxicity Multi-Liposomal Assemblies
2013
Anionic liposomes are electrostatically complexed to a star-shaped cationic polyelectrolyte. Upon complexation, the liposomes retain their integrity and the resulting liposome-star complexes do not dissociate in a physiological solution with 0.15 M NaCl. This provides a multi-liposomal container for possible use as a high-capacity carrier.
Hetero-difunctional dimers as building blocks for the synthesis of poly(amidoamine)s with hetero-difunctional chain terminals and their derivatives
2012
This article reports on a simple and straightforward preparation method of poly(amidoamine)s (PAAs) with hetero-difunctional chain ends as well as of several up to now hardly obtainable PAA derivatives of biotechnological interest, such as for instance PAAs of controlled molecular weight and narrow polydispersity mono-functionalized at one end with an acrylamide group, PAAs with star-like molecular architecture, graft-PAA-protein conjugates, “tadpole-like” PAA conjugates with hydrophobic moieties able to self assemble into nanoparticles in aqueous media. The key step was to design suitable building blocks consisting of hetero-difunctional dimers (HDDs). In particular, the HDDs considered we…