Chromatographic mode transition from size exclusion to slalom chromatography as observed for chitosan.

Elution behavior of chitosan was studied using narrow-bore size exclusion chromatography (SEC) columns packed with 8 μm porous particles at different eluent flow rates. Delayed elution of the largest chitosan species from the columns was observed at high flow rates, which was attributable to strong chain deformation rather than chain degradation. In particular, a chromatographic mode transition from SEC to slalom chromatography (SC) was observed for high molar mass chitosan samples with abnormal elution behaviors, which originates from the coil-stretch transition of chitosan chains in elongational flow through the columns.

Adsorption of poly(vinyl alcohol) on gel permeation chromatography columns depends on the degree of hydrolysis.

Both fully (98%) and partially (88%) hydrolyzed poly(vinyl alcohol) (PVA) are characterized by aqueous gel permeation chromatography (GPC) coupled with multi-angle laser light scattering. Polymer adsorption on hydrophilic GPC columns is observed for partially hydrolyzed PVA but not for fully hydrolyzed PVA, which is driven by the hydrophobic interactions between the residual acetate groups on PVA and the stationary phase. Desorption of these partially hydrolyzed PVA chains from the packing materials is monitored by decay of the light scattering signal.

Strategy to improve the characterization of chitosan by size exclusion chromatography coupled with multi angle laser light scattering.

Here we present SEC-MALLS study for chitosan samples with weight average molar mass M between 33 and 427 kg/mol on columns packed with 8 μm porous particles. A low injection concentration on the order of 0.1-0.

Phase behavior of poly(sulfobetaine methacrylate)-grafted silica nanoparticles and their stability in protein solutions.

Biocompatible and zwitterionic poly(sulfobetaine methacrylate) (PSBMA) was grafted onto the surface of initiator-modified silica nanoparticles via surface-initiated atom transfer radical polymerization. The resultant samples were characterized via nuclear magnetic resonance, Fourier transform infrared spectroscopy, transmission electron microscopy, and thermogravimetric analysis. Their molecular weights and molecular weight distributions were determined via gel permeation chromatography after the removal of silica by etching.

pH/Temperature-responsive behavior of amphiphilic block copolymer micelles prepared using two different methods.

The pH- and temperature-responsive behavior of amphiphilic block copolymer poly(L-lactide)-b-poly(2-(dimethylamino)ethyl methacrylate) (PLLA-b-PDMAEMA) in aqueous solutions is investigated using static and dynamic light scattering. Electrostatic force, hydrophobic interaction, and hydrogen bonding coexist in the system. Micelles with different structures are prepared using water addition (WA) and direct dissolution (DD) methods.

Analysis of interfacial phenomena of aqueous solutions of polyethylene oxide and polyethylene glycol flowing in hydrophilic and hydrophobic capillary viscometers.

Viscosities of aqueous solutions of five polyethylene oxide (PEO) samples with molar masses from 1.5 x 10(5) to 1.0 x 10(6) were carefully measured in a polytetrafluoroethylene (PTFE) capillary Ubbelohde viscometer in the concentration range from dilute down to extremely dilute concentration regions and compared with those of the same sample obtained from a glass capillary viscometer.