Abstract
Abstract - All over the world standards for Gel Permeation Chromatography (GPC) are produced using ionic polymerization. Standards are commercialized in a broad range of molecular weight and their dispersity (Ð) must be lower than 1.1. This work proposes the synthesis of polystyrene standards using Nitroxide Mediated Polymerization (NMP), an alternative technique to produce controlled polymers that is much more robust when compared to ionic polymerization. Standards with different ranges of molecular weights were obtained, all of them with very narrow molecular weight distribution (MWD) and dispersity (Ð) lower than 1.10. In order to do that, several combinations of different initiators were tested. Advanced GPC Triple Detector was used to obtain important properties, such as absolute number and weight average molecular weights, dispersity and intrinsic viscosity. The analytical method used in the characterization of the samples was in-house validated in terms of linearity, accuracy, precision, repeatability and robustness. The validation study demonstrated the quality of the measurements and ensured that the information obtained for a given analyte by the GPC technique is reliable.
Highlights
In the last two decades, reversible-deactivation radical polymerization, before called controlled radical polymerization or living radical polymerization, has been used to produce polymers with highly controlled microstructure
The first section below summarizes all syntheses performed in order to obtain polymers suitable to be used as Gel Permeation Chromatography (GPC) standard
Synthesizing Different Polymers to Be Used as GPC Standards as controller, where RI=[I1]:[I2] is the initiator ratio, [IT] is the total concentration of initiator in the reaction, and R=TEMPO]:[I] is the [controller]/[initiator] ratio
Summary
In the last two decades, reversible-deactivation radical polymerization, before called controlled radical polymerization or living radical polymerization, has been used to produce polymers with highly controlled microstructure. A polymer is considered controlled if it exhibits: a) a linear evolution of ln[1/(1conversion)] versus time, (b) a linear increase of the number-average molar mass (Mn) versus conversion and (c) dispersity indexes (Ð) lower than 1.5. Research in this area usually follows one of the three techniques: Atom Transfer Radical Polymerization (ATRP), Reversible Addition-Fragmentation ChainTransfer (RAFT) and Nitroxide Mediated Polymerization (NMP). Solomon et al (1986) were the first researchers to use nitroxide radicals in free radical polymerization, but they synthesized only polymers with low molecular Nitroxide Mediated Polymerization involves the addition of a controller or trapping agent (stable nitroxide radical) to capture the growing chain. Solomon et al (1986) were the first researchers to use nitroxide radicals in free radical polymerization, but they synthesized only polymers with low molecular
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