A Slot-Die Technique for the Preparation of Continuous, High-Area, Chitosan-Based Thin Films

Abstract

Chitosan-based films have a diverse range of potential applications but are currently limited in terms of commercial use due to a lack of methods specifically designed to produce thin films in high volumes. To address this limitation directly, hydrogels prepared from chitosan, chitosan-tetraethoxy silane, also known as tetraethyl orthosilicate (TEOS) and chitosan-glutaraldehyde have been used to prepare continuous thin films using a slot-die technique which is described in detail. By way of preliminary analysis of the resulting films for comparison purposes with films made by other methods, the mechanical strength of the films produced was assessed. It was found that as expected, the hybrid films made with TEOS and glutaraldehyde both show a higher yield strength than the films made with chitosan alone. In all cases, the mechanical properties of the films were found to compare very favorably with similar measurements reported in the literature. In order to assess the possible influence of the direction in which the hydrogel passes through the slot-die on the mechanical properties of the films, testing was performed on plain chitosan samples cut in a direction parallel to the direction of travel and perpendicular to this direction. It was found that there was no evidence of any mechanical anisotropy induced by the slot die process. The examples presented here serve to illustrate how the slot-die approach may be used to create high-volume, high-area chitosan-based films cheaply and rapidly. It is suggested that an approach of the type described here may facilitate the use of chitosan-based films for a wide range of important applications.

Sustainable Lignin-Reinforced Chitosan Membranes for Efficient Cr(VI) Water Remediation

“…Despite not performing NMR in this study, previous studies by the authors performed on the same commercial CS after processing have estimated a DD of 78%, which is very near to the 75% claimed by the manufacturer, confirming CS stability [73]. Furthermore, the molecular weight of the same commercial CS is between 50,000 and 190,000 Da in other works [74,75].…”

A Method for the Immobilization of Chitosan onto Urinary Catheters

“…The same observation was also reported by Carette et al [ 14 ]. Such interactions are well-known to appear in hydrogels [ 27 , 28 ]. The chitosan is thus mainly immobilized by noncovalent interactions, as illustrated in Figure 10 .…”

Polydimethylsiloxane Organic–Inorganic Composite Drug Reservoir with Gliclazide

“…Tetraethyl orthosilicate (TEOS), a silica precursor alkoxysilane that has been extensively studied in the crosslinking of PDMS [31][32][33], was also reported to form a silica-alginate hybrid composite [34,35] either by the interaction with alginate [35] or coating the crosslinked Ca-alginate surface [34]. TEOS, on the other hand, was reported to interact non-covalently with chitosan to form a pH-sensitive interpenetrative polymeric network (either by van der Waals attraction or through H-bonding) [36][37][38][39][40][41][42]. This physical crosslinking between the entangled polymeric chains of chitosan and TEOS produced a unique film that was mechanically strong due to TEOS and flexible due to chitosan and was investigated in modifying drug release [36][37][38][39][40][41][42].…”

“…TEOS, on the other hand, was reported to interact non-covalently with chitosan to form a pH-sensitive interpenetrative polymeric network (either by van der Waals attraction or through H-bonding) [36][37][38][39][40][41][42]. This physical crosslinking between the entangled polymeric chains of chitosan and TEOS produced a unique film that was mechanically strong due to TEOS and flexible due to chitosan and was investigated in modifying drug release [36][37][38][39][40][41][42].…”