Characterization of poly(ethylene glycol)-b-poly(ε-caprolactone) by liquid chromatography under critical conditions: Influence of catalysts and reaction conditions on product composition

PolyCrit: An Online Collaborative Platform for Polymer Characterization

Polymer liquid chromatography at critical conditions (LCCC) is a chromatographic separation condition achieved by carefully balancing the interaction of a polymer with stationary and mobile phases to make the elution time of a polymer in chromatography independent of its molecular weight. By removing the dependence of elution time on polymer molecular weight, the LCCC then allows separation of polymer samples on the basis of secondary differences, such as topology, branching, and end-group functionality, that are otherwise difficult to resolve. Despite its potential, LCCC remains under-employed due to the complexity of its optimization and the scattered nature of existing data. To address these challenges, we developed PolyCrit, a database that organizes 428 critical chromatography conditions (characterized by 33 parameters) into a searchable and accessible online platform. PolyCrit centralizes decades of literature, providing detailed information on polymers, solvents, stationary phases, and chromatographic parameters. It features a quality scoring system to ensure data reliability and supports contributions from the research community through a validation process. By curating experimental critical conditions, PolyCrit reduces the need for extensive literature searches to utilize the powerful chromatographic technique. Additionally, PolyCrit invites current researchers to contribute to the database by submitting their own work. It can be found at https://lccc.ywangcomp.org.

Novel epoxy-terminated macromonomers and their polymerization for synthesis of bottle-brush type amphiphilic block copolymers

Architecture of polymers has vital implications for their physical properties and applications. In this study, synthesis of a series of novel epoxy-terminated macromonomers namely Ep-DEGMME, Ep-TEGMME, Ep-EGMEE, Ep-EGMBE, and Ep-EGMHE is reported. The synthesized macromonomers vary in number of ethylene oxide units and length of the alkyl group. These macromonomers are first homopolymerized by anionic ring-opening polymerization for synthesis of homopolymers of a molar mass range. Subsequently, these macromonomers with different lengths of two segments (alkyl group and ethylene oxide units) are copolymerized with other monomers for synthesis of bottle-brush type architectures. In the first case, di- and tri-block copolymers of Ep-EGMBE are synthesized while using MeO-PEG or PEG as a macroinitiator; the resulting block copolymers have hydrophilic handle and hydrophobic brush. On the same lines, block copolymers of Ep-TEGMME with ε-caprolactone have hydrophobic handle and hydrophilic brush. The synthesized block copolymers are comprehensively characterized by SEC and liquid chromatography at critical conditions. The analysis reveals the successful synthesis of block copolymers while providing information on relative total molar mass, and individual block lengths of the block copolymers, along with amount of unwanted homopolymers in the sample.

Chromatographic characterization of amphiphilic di- and tri-block copolymers of poly(ethylene oxide) and poly(ε-caprolactone)

Amphiphilic di- and tri-block copolymers based on poly(ethylene oxide) as a hydrophilic segment and poly(ε-caprolactone) as a hydrophobic part are synthesized by the ring-opening polymerization of ε-caprolactone while using poly(ethylene glycol)s and methoxy poly(ethylene glycol)s of varying molar masses as macro-initiators. The synthesized block copolymers are characterized with respect to their total relative molar mass and its distribution by size exclusion chromatography. Liquid chromatography at critical conditions of both blocks is established for the analysis of individual block lengths and tracking presence of unwanted homopolymers of both types in the block copolymer samples. New critical conditions of polycaprolactone on reversed phase column are reported using organic mobile phase. The established critical conditions of polycaprolactone extended the applicable molar mass range significantly compared to already reported critical conditions of polycaprolactone in aqueous mobile phase. Block copolymers are also analyzed at critical conditions of poly(ethylene glycol). Complete analysis of the di- and tri-block copolymers at corresponding critical conditions provided a fair estimate of molar mass of non-critical block besides information regarding presence of homopolymers of both types in the samples.

Synthesis and meticulous molecular, morphological and thermal characterization of linear and star-shaped polycaprolactones

Linear and star-shaped polycaprolactones: two-dimensional separation.