PAT for Cycloaddition Click Reaction
Zhang, Y., Lai, W., Xie, S. Q., Zhou, H., & Lu, X. (2021b). Facile synthesis, structure and properties of CO2-sourced poly(thioether-co-carbonate)s containing acetyl pendants via thio-ene click polymerization. Polymer Chemistry, 13(2), 201–208. https://doi.org/10.1039/d1py01477c
Aliphatic polycarbonates are proving to be significant in biomedical applications and the synthesis of novel APCs are actively researched. In this work, poly(thioether-co-carbonate)s are synthesized bearing acetyl groups attached to vinyl-groups functionalized bis- and tris-β-oxo-carbonates. The aliphatic polycarbonates with thio-linkages in the main chain and acetyl pendants in each repeating unit were prepared via photochemical-induced thiol-ene click polymerization of the bis- and tris-vinyl-β-oxo-carbonates with primary bisthiols. These polycarbonates are readily depolymerized under mild conditions using t-butyl peroxide, producing peroxy-substituted cyclic carbonates and polyols. This degradation was demonstrated using in-situ FTIR.
C=O stretching bands in the polymer were identified arising from the carbonate (1746 cm−1) and from the attached acetyl group (1723 cm−1). These C=O absorption bands diminished over time after 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and tert-butyl hydroperoxide (TBHP) were added to the reaction system. The presence of a new top at 1809 cm−1 arising from the C=O stretching band of a cyclic carbonate was associated with the formation of peroxy-functionalized biscyclic carbonates, and reflective of polymer degradation.
In-Situ FTIR for Thermoplastic Elastomers
Bretzler, V., Grübel, M., Meister, S., & Rieger, B. (2014b). PDMS-Containing Alternating Copolymers Obtained by Click Polymerization. Macromolecular Chemistry and Physics, 215(14), 1396–1406. https://doi.org/10.1002/macp.201400178
This research highlights the advantages of thermoplastic elastomers (TPE) over chemically crosslinked elastomeric polymers that require costly catalysts and require additional considerations. TPE offers benefits in thermal processing, making them a valuable choice for applications such as 3D printing and injection molding. Notably, this study demonstrates that poly(dimethylsiloxane) can be used as segments in TPE, and CuAAC click reactions can construct linear polymers based on PDMS.
The authors extend this research by showcasing the incorporation of various functionalities in a PDMS-containing alternating copolymer via the CuAAC reaction, which results in the formation of TPE with diverse properties. The authors explore structure-property relationships, which are dependent on the different azido-functionalized oligosiloxane segments, as well as the geometries of the various dialkyne comonomers used in the polymerizations.
The ReactIR in-situ FTIR spectrometer provided insights into polymerization kinetics by tracking the decay of the azide functionality during the reaction. Furthermore, in-situ FTIR measurements demonstrated a significant enhancement in the polymerization reaction rate with the addition of one equivalent of the tridentate triazole ligand tris((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)amine (TBTA) to the CuAAC reaction. Moreover, the optimal ratio of ligand-to-metal for achieving the accelerating effect was determined to be between 0.5 to 1.0 eq, resulting in the highest reaction rate. This study sheds light on the potential of TPE and provides a comprehensive understanding of their properties and capabilities.