A Unified Approach to Understanding Polyelectrolytes by Monitoring their Synthesis and Associated Endproduct Characteristics with Novel Methods

Tulane University, New Orleans LA

Investigators

Abstract

ABSTRACT PI: Wayne F. Reed Institution: Tulane University Proposal Number: 0623531 Title: A unified approach to understanding polyelectrolytes by monitoring their synthesis andassociated endproduct characteristics with novel methods Copolymeric polyelectrolytes, in which at least one comonomer species is charged can be termed 'copolyelectrolytes'. A novel and unified approach to understanding the kinetics and mechanisms of copolyelectrolyte synthesis and the physical characteristics of the resulting polymers will be made using new analytical instrumentation and methods developed in the PI's lab. These include Automatic Continuous Online Monitoring of Polymerization reactions (ACOMP), Automatic Continuous Mixing (ACM) for equilibrium characterization of polyelectrolytes, and Simultaneous Multiple Sample Light Scattering (SMSLS) for monitoring aggregation, phase separation, degradation, and other processes. Approaches based on these methods will allow understanding of the process, including connecting the synthesis kinetics to the resulting 'trivariate' distribution of composition, mass, and linear charge density, which in turn controls the physical properties of end product solutions, such as chain conformations, interparticle interactions, viscosity, interactions with colloids and other polymers, solution stability, and more. The complex interplay of the distributions and factors creating them (e.g. ionic strength, comonomeric species, ratios) will be explored with combinations of charged and neutral comonomers, using free and controlled radical mechanisms. The methods will also be adapted to copolyelectrolytes formed through post-polymerization modification processes, such as quaternization, hydrolysis, and grafting. Size ExclusionChromatography will be developed to provide a complementary validation of the linear charge density and mass distributions and correlate them with those determined from ACOMP. Other traditional methods, such as titration and FT-IR will be used for cross-checks. Intellectual merit. The unified results will allow testing and improvement of existing polymer theories, including counterion condensation, descriptions of binary and ternary interactions of dissimilar species, scattering from multicomponent systems, and the effects on polyelectrolytes of pH, and added electrolyte valence, symmetry, and ionic strength. This work will develop advanced polyelectrolyte characterization methods applicable in many fields, and will set the stage for studying even more complex copolyelectrolytes. The work should provide the tools and kinetic understanding necessary to produce many different polyelectrolyte materials, including 'on-command', single synthesis blends of different polyelectrolytes and neutral polymers. Broader impact: Besides providing new approaches to polyelectrolyte research, ACOMP and ACM have the potential to become widely applicable analytical methods. ACOMP, in particular, is also poised to have strong impact in the global polymer market. When adapted to control industrial level reactions, ACOMP can bring significant savings of energy, nonrenewable resources, plant and personnel time, and increase product quality. The interdisciplinary nature of this work, involving Physics, Chemistry, and Chemical and Process Engineering leads naturally to cross-fertilization of ideas, and the collaboration of broad-based academic and industrial partners. The PI's group has key partnerships with the private sector instrumentation and polymer industries, including a Tulane Center of Excellence for Online Polymer Characterization now forming. This is creating increasing opportunities for students and postdocs both in the range of their research projects and in their job prospects. The PI's group also hosts and trains a growing number of industrial scientists and engineers, who bring their expertise back to the private sector. Typically, half the PI group members are women.