Monitoring the Synthesis and Properties of Copolymeric Polycations

Abstract

The kinetics; evolution of molar mass; solution conductivity, sigma; intrinsic viscosity; and average composition drift; and distribution were determined by monitoring the synthesis of copolymeric polycations of acrylamide (Am) and [2-(acryloyloxy)ethyl]-trimethylammonium chloride (Q9). The quantitative relationship between diminishing sigma and charged co-monomers incorporation was monitored for the first time and provided novel data on counterion condensation, which occurs gradually over a broad composition regime. This new capability allows predictions concerning the relationship between copolymer composition and linear charge density, xi, to be tested and models of trivariate mass, composition, and xi distributions to be built. This approach, hence, brings together the previously disparate fields of synthetic chemistry of copolymers and physical chemical properties of polyelectrolytes. Monitoring was achieved with a new implementation of the ACOMP (automatic continuous online monitoring of polymerization reactions) platform. Reactivity ratios determined by ACOMP were rQ9 = 0.47 and rAm = 1.10. Opposite trends in composition drift and final molar mass were found; low starting percentage of Q9 led to low composition drift and high molar mass, whereas the opposite was found at high starting percentage of Q9. Complementary end-product analysis by multidetector gel permeation chromatography supported the ACOMP results. End-product polyelectrolyte properties were characterized by automatic continuous mixing, revealing that combined electrostatic persistence length and excluded volume effects led to the expected large changes in polyelectrolyte conformation and interactions. These results set the groundwork for semibatch control of molar mass, composition, and xi, and eventually for monitoring and control for inverse emulsion-based reactions of this type.

Experimental and Modeling Study of Acrylamide Copolymerization with Quaternary Ammonium Salt in Aqueous Solution

“…The resulting charged macromolecules are subject to electrostatic inter- and intramolecular interactions, and such interactions explain the peculiar behavior of polyelectrolytes in solution . As a matter of fact, the mutual correlation between some fundamental solution properties of polyelectrolytes, such as intrinsic viscosity, ionic strength, solution conductivity, molecular weight, and polymer chain conformation, is not yet clearly understood or easily predicted. − …”

“…Cationic polymers, also referred to as polycations, are polyelectrolytes leaving macrocations after dissociation. They are mainly used as flocculants in wastewater treatment and paper-making industry, in the stabilization–destabilization of emulsions, and in the production of cosmetics and pharmaceuticals. , Latest applications of these materials are found in the biochemical and medical fields, such as the manufacture of implant coatings and controlled drug delivery devices . Indeed, nanoparticles made of polycations can be effectively used to package genetic material (e.g., siRNA) in order to bypass degradative bioenvironments and achieve targeted release …”

“…In particular, special attention has been devoted to the characterization of the evolution of copolymer composition of polyelectrolytes as well as of the polymer properties (e.g., conductivity, molar mass, intrinsic viscosity) during the polymerization reaction. Mayo–Lewis plots and reactivity ratios have been obtained experimentally for various relevant copolymers involving quats: AAm- co -(DMAEA-Q), ,,,,,− AAm- co -(DMAEM-Q), ,,,, AAm- co -DADMAC, ,, (di-M)- co -AAm, and (di-M)- co -(DMAEA-Q) …”

“…The system is first investigated experimentally with the aim of characterizing reaction kinetics and evolution of copolymer composition. Few works about the investigation of the copolymerization of this cationic monomer with AAm can be found in the literature. ,,,,,− As an improvement to the previous studies, the effect of reaction parameters such as initial monomer concentration and composition is thoroughly investigated in this work, specifically extending the analysis from very low to highly concentrated solutions, in order to shed light on the composition behavior. A state-of-the-art technique based on 1 H NMR spectroscopy is adopted to collect very accurate data of monomer conversion and composition as a function of time.…”

Automatic Control of Polymer Molecular Weight during Synthesis

“…The molecular weight can be simultaneously controlled by the total rates of A and B feed, where p can now be a function of instantaneous comonomer concentrations and can also be recomputed if and as it changes during copolymerization. ACOMP has been used extensively for monitoring copolymerization reactions, − so that the underlying methodology needed to provide composition information to the copolymerization controller already exists.…”