Compact polyelectrolyte complexes from polysaccharidic precursors

• Grant number: 23/07740-1
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: August 01, 2023
• End date: June 30, 2027
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Watson Loh
• Grantee: Guilherme Henrique Vedovello Silva
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 21/12071-6 - Tailoring colloids through supramolecular interactions: from fundamentals to applications, AP.TEM

Abstract

In this PhD project, compact polyelectrolyte complexes (CoPECs) with pH-controlled ion pairing behavior and ionic strength of the medium will be studied, using renewable and biodegradable polysaccharides as precursor materials. The project will focus on the use of cellulose, chitin, and their nanoparticulate (nanocrystals and nanofibers) and molecular derivatives, chemically modified to form strong polyelectrolytes (i.e., with pH-independent ionization) and/or weak polyelectrolytes (i.e., with pH-dependent ionization). Although there is significant scientific activity in exploring new applications of polysaccharides such as cellulose and chitin, little has been explored regarding the formation of CoPECs derived from these polysaccharides and the saloplastic properties of the complexes. The complexation kinetics between the polyelectrolyte pairs will be studied using methods such as isothermal titration calorimetry (ITC), quartz crystal microbalance with dissipation (QCM-D), and cryogenic transmission electron microscopy (Cryo-TEM), and correlated with the morphology, environmental conditions, and stoichiometry between charged groups. With the optimal complexation conditions determined, CoPECs will be produced using salt solutions as plasticizers through methods such as extrusion, ultracentrifugation, and 3D printing, aiming to produce materials with complex geometry and exploring the saloplastic properties of the complexes, aiming to develop materials such as reversible underwater adhesives, self-repairing gels, solid foams, and recyclable films. An important characteristic sought in these materials will be the control and reversibility of complexation. The possibility of returning to the precursor solution/suspension under specific pH or salinity conditions will be utilized for reprocessing and/or programmed disintegration, such as for single-use plastics in high salinity conditions like those in the ocean. (AU)