Influence of chain length on the molecular dynamics of an aliphatic ionene

An aliphatic random copolymer ionene (a cationic polyelectrolyte with N + in the repeat unit), was fractionated with the continuous polymer fractionation and investigated for its molecular weight dependent properties. The fractions were analyzed with GPC and capillary viscometry for their molecular weight. Glass transition temperatures were determined with DSC and a strong molecular weight dependence was observed, but no influence in the ionic conductivity was observed. The temperature dependency of ionic conductivity in ionenes is described.

Rheology of Sodium Hyaluronate Saline Solutions for Ophthalmic Use

The aim of this work was to investigate the rheological properties of different saline solutions of sodium hyaluronate (NaHA) with special interest for medical applications. The experimental results were compared with literature data for commercial ophthalmic viscosurgical devices (OVDs) used in cataract surgery. We offer some tools to tailor the rheological behavior of OVDs for different purposes. We have investigated to which extent surgical requirements can be fulfilled by adjusting either the molecular weight of NaHA or its concentration, parameters that are in some respects equivalent but not in others. Furthermore, we demonstrate that moduli and complex viscosities of NaHA saline solu…

Cover Picture: Macromol. Mater. Eng. 5/2004

Inverse Spin Fractionation:  a Tool to Fractionate Sodium Hyaluronate

Biocompatibility of alginates for grafting: impact of alginate molecular weight.

Optimising microencapsulation technology towards the effective clinical transplantation has created the need for highly biocompatible alginates. Therefore, in this study the biocompatibility of different beads prepared from alginates with varying average molecular weight was examined. In some experiments the beads were covered with a multilayer membrane surrounded by an alginate layer. First of all, we found that beads made of a lower weight average alginate elicted a much stronger fibrotic response compared to beads made of a higher weight average alginate (LV-alginate > MV-alginate). The results were confirmed by the observation that the extent of tissue fibrosis was significantly increas…

Large Scale Fractionation of Macromolecules

Access to sufficiently large amounts of material with adequate molecular and chemical uniformity from polydisperse natural products or synthetic materials has been a long-standing challenge to polymer scientists. We have developed a broadly applicable preparative fractionation method consisting of a special kind of continuous extraction removing the easier soluble components from the initial product. It is rendered possible by the use of spinning nozzles throught which a concentrated polymer solution is pressed into a liquid of tailored thermodynamic quality. The initially produced jets of the source phase disintegrate rapidly into minute droplets of typically 50 μm diameter. This efficient…

Molar Mass Distribution and Size of Hydroxyethyl Starch Fractions Obtained by Continuous Polymer Fractionation

By the use of continuous polymer fractionation (CPF) the initial polymer can be separated into fractions of different molar masses, which makes it possible to obtain hydroxyethyl starch (HES) fractions tailor-made for specific application. Two samples of HES (HES A and HES B) were fractionated by means of CPF. By size-exclusion chromatography-multi-angle laser light-scattering-differential refractive index (SEC/ MALLS/DRI) measurements it was shown that CPF is able to remove the low-molar-mass components and to adjust the samples to various desired molar masses with lower polydispersities than the original samples. In terms of the weight-average mean molar mass M w , the sol fractions have …