Photopolymerizable Ionogel with Healable Properties Based on Dioxaborolane Vitrimer Chemistry

Ionogels are solid polymer gel networks loaded with ionic liquid (IL) percolating throughout each other, giving rise to ionically conducting solid electrolytes. They combine the mechanical properties of polymer networks with the ionic conductivity, non-volatility, and non-flammability of ILs. In the frame of their applications in electrochemical-based flexible electronics, ionogels are usually subjected to repeated deformation, making them susceptible to damage. It appears critical to devise a simple and effective strategy to improve their durability and lifespan by imparting them with healing ability through vitrimer chemistry. In this work, we report the original in situ synthesis of polythioether (PTE)-based vitrimer ionogels using fast photopolymerization through thiol-acrylate Michael addition. PTE-based vitrimer was prepared with a constant amount of the trithiol crosslinker and varied proportions of static dithiol spacers and dynamic chain extender BDB containing dynamic exchangeable boronic ester groups. The dynamic ionogels were prepared using 50 wt% of either 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide or 1-Ethyl-3-methylimidazolium trifluoromethanesulfonate, both of which were selected for their high ionic conductivity. They are completely amorphous (T_g below -30 °C), suggesting they can be used at low temperatures. They are stretchable with an elongation at break around 60%, soft with Young's modulus between 0.4 and 0.6 MPa, and they have high ionic conductivities for solid state electrolytes in the order of 10^-4 S·cm^-1 at room temperature. They display dynamic properties typical of the vitrimer network, such as stress relaxation and healing, retained despite the large quantity of IL. The design concept illustrated in this work further enlarges the library of vitrimer ionogels and could potentially open a new path for the development of more sustainable, flexible electrochemical-based electronics with extended service life through repair or reprocessing.

Transformation of Thioester-Initiated Star Polymers into Linear Arms via Native Chemical Ligation

The synthesis of a new class of Cu-mediated polymerization initiators with thioester functionality is demonstrated and their polymerization kinetics via single-electron transfer living radical polymerization is reported. From periodic sampling, it is found that thioester- or ester-based initiators can be employed interchangeably, resulting in very similar polymerization rates. Furthermore, a multifunctional thioester initiator is employed for the preparation of a well-defined four-arm star-shaped polymer. It is further shown that the full dissociation of the star polymer into linear arms via native chemical ligation can easily be followed via size exclusion chromatography, as a result of the change in hydrodynamic volume. Finally, the obtained linear polymers are characterized via matrix-assisted laser desorption/ionization-time of flight mass spectrometry and found to be in good agreement with the expected molecular weight distribution that confirms the successful transformation.

Copper mediated RDRP of thioacrylates and their combination with acrylates and acrylamides

Ethyl thioacrylate was polymerised via Cu-RDRP and subjected to amidation to obtain the first “all-acrylic” copolymer.

Thioester functional polymers

Inspired by the uniqueness and ubiquity of thioesters in nature, much attention has been paid to thioester functionalized materials, yielding applications ranging from responsive polymers to bioconjugates and (bio)degradable polymers.

Polymer structure-property requirements for stereolithographic 3D printing of soft tissue engineering scaffolds

This review highlights the synthesis, properties, and advanced applications of synthetic and natural polymers 3D printed using stereolithography for soft tissue engineering applications. Soft tissue scaffolds are of great interest due to the number of musculoskeletal, cardiovascular, and connective tissue injuries and replacements humans face each year. Accurately replacing or repairing these tissues is challenging due to the variation in size, shape, and strength of different types of soft tissue. With advancing processing techniques such as stereolithography, control of scaffold resolution down to the μm scale is achievable along with the ability to customize each fabricated scaffold to match the targeted replacement tissue. Matching the advanced manufacturing technique to polymer properties as well as maintaining the proper chemical, biological, and mechanical properties for tissue replacement is extremely challenging. This review discusses the design of polymers with tailored structure, architecture, and functionality for stereolithography, while maintaining chemical, biological, and mechanical properties to mimic a broad range of soft tissue types.

Direct synthesis of thiol-terminated poly(ε-caprolactone): a study on polymerization kinetics, mechanism and rare earth phenolates' structure–activity relationship

Polymerization kinetics, mechanism and rare earth phenolates' structure–activity relationship were investigated for direct synthesis of thiol-terminated poly(ε-caprolactone).