Chitosan Molecules Deposited from Supercritical Carbon Dioxide on a Substrate: Visualization and Conformational Analysis

Abstract

We deposited single individual macromolecules of chitosan directly from their solutions in supercritical carbon dioxide onto a substrate surface and applied SFM method to analyze the macromolecular conformation. By means of image processing of many different SFM‐contours of the visualized individual macromolecules, we determined the scaling exponent ν, which describes the correlation between mean square end‐to‐end distances and contour lengths of the adsorbed macromolecules. It was revealed, that the macromolecules, deposited from scCO2 and visualized by SFM, tended to adopt rather extended conformation. The scaling exponent ν was found to be in range of 0.78–0.8, which was slightly above the 3/4 value, corresponding to 2D self‐avoiding walk statistics. Good adhesion of chitosan coatings directly deposited from scCO2 is expected.

Chitosan Nanogels by Template Chemical Cross-Linking in Polyion Complex Micelle Nanoreactors

“…that found the existence of a critical homopolymer chain length beyond which the size of PIC micelles increases with increasing homopolymer block length . The critical length values found by these authors are higher, but it has to be considered that the contour length of the repeating unit of chitosan (0.52 nm) − is higher than that of a vinyl polymer (0.25 nm) and that chitosan has a very extended chain conformation because of the β(1–4) glycosidic linkage . This could hamper the formation of a pure coacervate core, giving rise to the formation of large particles with mixing of core and shell forming chains. , …”

All‐Dielectric Nanostructures with a Thermoresponsible Dynamic Polymer Shell

“…To perform bio integration of the NPs, different strategies as functionalization or decoration by polyelectrolytes (PE) can be realized. Generally, the structural rearrangement mechanism in PE is rather uniform and is known in polymer physics as the coil‐globule transition, defined as the reversible transition of macromolecules from an expanded coil state through an ideal coil state to a collapsed globule state [29–31] . Triggers of such transitions in polymers can be restricted to chemical (pH, [23] ionic strength, [32] solvent [33] ), physical (temperature [34, 35] ) stimuli, and a mechanical impact [36] .…”

“…High‐modulation morphological swelling can be achieved by the deposition of pH‐sensitive charged block copolymers, block‐copolymer micelles, and the formation of PE brushes [37] . The mechanism of high‐amplitude changes of the PE shell is based on the expansion/collapse of macromolecules, thus regulating the whole shell's length and density [29, 36] …”

“…[37] The mechanism of high-amplitude changes of the PE shell is based on the expansion/collapse of macromolecules, thus regulating the whole shells length and density. [29,36] In a well-known thermo-responsible system based on Au NP and poly-(N-isopropyl acrylamide) (PNIPAM) the shell usually collapses due to temperature. Kçhler et al [38,39] described the similar shrink for poly-(diallyldimethylammonium chloride) (PDADMAC) and poly-(sodium 4-styrenesulfonate) (PSS) assembly.…”

Produção e caracterização de quitosana imobilizada em substratos visando adsorção de ions metalicos

“…A etapa da aplicação do recobrimento pode ser realizada por diversas técnicas como recobrimento em leito de jorro (MARQUES, 2007), métodos de deposição a vácuo, "dip coating", "sping coating", "spray coating", outras estão sendo desenvolvidas como o recobrimento de partículas utilizando CO 2 supercrítico (GALLYAMOV et al, 2008). A escolha da técnica adequada depende do tipo de material e da solução de recobrimento e é importante para que ocorra um recobrimento eficiente.…”