Poly(ethylene oxide)-based polyoxyalkylene block copolymers have been developed and commercialized for more than half century and are still being used in many different fields such as cosmetics, cleaners, lubricants, and medicines. This type of amphiphilic block copolymer is able to self-assemble into nanoscopic structures. Significant effort has been put into the development of a series of nanosized therapeutic products to solubilize hydrophobic drugs, allow their sustained release, improve their pharmacokinetics, and facilitate their access to the site of action. Besides the copolymers with propylene oxide, block copolymers with 1,2-butylene oxide (BO) have received special attention due to their potential to control rheological properties in aqueous systems as associate thickeners and their bioactivity when used as drug delivery carrier. It has been postulated, demonstrated by computer simulation, and proven by experimental measurements that the self-assembly behavior of block copolymers can be impacted by their dispersities, such as the molecular weight dispersity of each block and of the chain, the compositional dispersity, and the dispersity of the block sequence, etc. The characterization of polyoxyalkylene block copolymers has been explored using many approaches; however, the quantification of different species in the reaction mixture is still unclear.<br/><br/>As polyoxyalkylene block copolymers are often synthesized by the anionic ring-opening polymerization of alkylene oxides, one has to take into account all the possible side reactions leading to the formation of homopolymers. In the presence of water, polyalkylene glycol may be formed and results in tri-block formation during the di-block copolymer preparation (see Figure below). This presentation will discuss our analytical approaches to identify the different species in the reaction mixture, and then to quantify the homopolymers and tri-block copolymers in polyoxyalkylene di-block copolymers.

Quantification of homopolymers and tri-block copolymers in polyoxyalkylene di-block copolymers

2019 Spring National Meeting

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