Controlled Deposition of Structured Polymer Films: Chemical and Rheological Factors in Chitosan Film Formation

Abstract

The technique of spread-coating was utilized to create thin films of chitosan polymer. The effect of deposition rate on film thickness was characterized for solutions of deacetylated and butyl-modified chitosan. For the range of deposition rates analyzed, the relationship between film thickness and increasing deposition rate fell into three distinct regions: an initial inverse relationship, a second linearly increasing relationship, and a final region wherein the film thickness remained constant. Results suggest that film thickness was both controllable and reproducible and that hydrophobic modification of the polymer extends the range over which a linear relationship between film thickness and deposition rate is achieved.Viscometry and fluorescence spectroscopy were employed to characterize the micellar characteristics of solutions of both deacetylated and butyl-modified chitosan.Deacetylated chitosan solutions possessed more interconnected hydrophobic domains that had more intermolecular micellar characteristics, while butyl-modified chitosan solutions had more intramolecular micellar characteristics and less interconnected hydrophobic domains.

Role of Vapor Mass Transfer in Flow Coating of Colloidal Dispersions in the Evaporative Regime

“…In the last few years, many groups performed experimental and theoretical investigations of this evaporative regime for dilute inks ranging from colloidal dispersions 5,[9][10][11][12][13][14] to solutions of polymers and small molecules. 4,[14][15][16] Despite the wide complexity of the process and the wide variety of reported phenomena, including streaks or stripes formation, [17][18][19] cracks and delamination 20 to name a few, many of the above cited works reported the following scaling:…”

“…Over the past few years, many groups have performed experimental and theoretical investigations of this evaporative regime for dilute inks ranging from colloidal dispersions ,− to solutions of polymers and small molecules. ,− Despite the wide complexity of the process and the wide variety of reported phenomena, including streak or stripe formation, − cracks and delamination, to name a few, many of the above cited works reported the following scaling for the dry deposit thickness h d as a function of the substrate velocity V and the reservoir particle volume fraction φ 0 . Such a robust scaling suggests a common explanation based on mass conservation arguments only.…”

Branched polyethylenimine-grafted-carboxymethyl chitosan copolymer enhances the delivery of pDNA or siRNA in vitro and in vivo

“…19,20 Above all, the polycationic character of chitosan has attracted many researchers in the field of gene therapy to use chitosan and its derivatives for applications as diverse as drug delivery, [19][20][21] tissue engineering, [22][23][24] antibiotic delivery, 25,26 and the preparation of chitosan-based biomaterials. 27,28 Several approaches that enable the chemical combination of chitosan and PEI to promote gene delivery were reported recently. [29][30][31][32][33][34] In the present study, O-carboxymethyl chitosangraft-branched polyethylenimine (OCMPEI) copolymers with various ratios of branched polyethylenimine (bPEI) were synthesized, and their suitability for the delivery of pDNA or siRNA was evaluated.…”