Superabsorbent hydrogels made from bio-sourced butyrolactone monomer in aqueous solution

A new water-soluble monomer, sodium 4-hydroxy-4-methyl-2-methylene butanoate (SHMeMB), formed by saponification of the bio-derived monomer γ-methyl-α-methylene-γ-butyrolactone (MeMBL), was copolymerized with acrylamide (AM) in aqueous solution to make superabsorbent hydrogels with equilibrium degree of swelling in the range of 6700–59 000%, depending on monomer ratio and crosslink density. Mechanical strength and storage and loss moduli of the hydrogels were tunable over a wide range through adjustment of the comonomer composition and the crosslinker content. Monomer reactivity ratios of rSHMeMB = 0.12–0.17 and rAM = 0.95–1.10 were determined using copolymer compositions measured at low monomer conversion as well as by applying the integrated form of the Mayo-Lewis equation to fit the drift in comonomer composition with conversion. The reactivity of the SHMeMB : AM system was lower than that of the previously-studied SHMB : AM system, with sodium 4-hydroxy-2-methylene butanoate (SHMB) derived from a similar renewable monomer, α-methylene-γ-butyrolactone (MBL). The differences in reactivity were studied by pulsed laser polymerization coupled with size exclusion chromatography; the comonomer-averaged propagation rate coefficient of the SHMB : AM system was found to be more than double that of SHMeMB : AM, with first estimates for the SHMeMB and SHMB homopropagation rate coefficients of 25 and 165 L mol−1 s−1, respectively, at 60 °C. Despite its lower reactivity, SHMeMB offers advantages over SHMB due to its availability and as superior overall properties of the final hydrogels were achieved.European Regional Development Fund through project POLYFRIEND, within Hungary-Slovakia Cross-border Co-operation Programme [HUSK 1101/1.2.1/0209]; Slovak Academic Information Agency (SAIA) [VEGA 2/0158/17]; Natural Sciences and Engineering Research Council of Canada (NSERC

Polyelectrolyte Complex Beads by Novel Two-Step Process for Improved Performance of Viable Whole-Cell Baeyer-Villiger Monoxygenase by Immobilization.

A novel immobilization matrix for the entrapment of viable whole-cell Baeyer–Villiger monooxygenase was developed. Viable recombinant Escherichia coli cells overexpressing cyclohexanone monooxygenase were entrapped in polyelectrolyte complex beads prepared by a two-step reaction of oppositely-charged polymers including highly defined cellulose sulphate. Immobilized cells exhibited higher operational stability than free cells during 10 repeated cycles of Baeyer–Villiger biooxidations of rac-bicyclo[3.2.0]hept-2-en-6-one to the corresponding lactones (1R,5S)-3-oxabicyclo-[3.3.0]oct-6-en-3-one and (1S,5R)-2-oxabicyclo-[3.3.0]oct-6-en-3-one. The morphology of polyelectrolyte complex beads was characterised by environmental scanning electron microscopy; the spatial distribution of polymers in the beads and cell viability were examined using confocal laser scanning microscopy, and the texture was characterised by the mechanical resistance measurements