Clickable polyurethanes based on s‐triazine ring containing aromatic diisocyanate bearing pendent alkyne group: Synthesis and postmodification

Abstract

A new s-triazine ring containing aromatic diisocyanate bearing a pendent alkyne group, namely, 2,4-bis(4-isocyanatophenoxy)26-(prop-2-yn-1-yloxy)21,3,5-triazine was synthesized and reacted with various diols viz., 1,10-decanediol, tetraethylene glycol and polyethylene glycols in the presence of dibutyltin dilaurate as the catalyst to obtain a series of linear polyurethanes. The selected polyurethanes possessing pendent alkyne groups were postmodified with chemically diverse azides viz., 1-(azidomethyl)benzene, 1-(azidomethyl)pyrene, and methoxy end-caped poly(ethylene glycol) azide via coppercatalysed azide-alkyne Huisgen 1,3-dipolar cycloaddition. FTIR and 1 H NMR spectra indicated quantitative click reaction. UVvis and fluorescence spectroscopic analysis confirmed complete incorporation of pyrenyl groups indicating the formation of fluorescence active polyurethane by postmodification with 1-(azidomethyl)pyrene. TG analysis of polyurethanes indicated two stage weight loss and their thermal stability, as judged by T 10 values, was governed by weight percent of urethane linkages. The water contact angle measurements revealed improved wettability with increased content of PEG either in the backbone of polyurethanes or as grafted chains. DLS and TEM studies confirmed that certain polyurethanes possessing PEG segments displayed self-assembly in aqueous solution, which was further supported by pyrene encapsulation studies using UV-vis spectroscopy.

Alcohol Moiety-Tethering Acylazides as Versatile Isocyanate Precursors for Polymerization Initiators and Monomers

“…Since the connecting part of the block polymer could affect the property of the material, this point would be also considered as an advantage. The above-mentioned synthetic approach may broaden the range of attainable molecular designs of polyurethane species, which are produced on a large scale at an industrial level, so that they can be studied as modern functional materials. − Against this backdrop, herein, we designed an orthogonal alcohol species comprising an acylazide moiety that could be used as a precursor of the isocyanate group, and we demonstrated the utility of this species in the facile preparation of an end-reactive polyester, polyurethane, and a block copolymer (Figure ). Furthermore, based on the initial result with 1 , 2 was developed as the catalyst-free agent.…”

Thermally Crosslinkable and Chemically Modifiable Aromatic Polyesters Possessing Pendant Propargyloxy Groups

“…The lowering of contact angle from 88° to 37° was observed upon grafting of PEG chains onto aromatic polyester backbone which could be possibly due to better spatial arrangement of the hydrophilic PEG moieties onto the polyester surface …”

“…Click reactions are highly selective as well as tolerant to a number of functional groups and can be carried out under mild conditions . The combination of step‐growth polymerization and click chemistry modification has been put to use for synthesis of a range of graft copolymers and functionalized polymers . Click chemistry modifications of aliphatic polyesters containing pendant clickable groups such as alkyne, azide, alkene, and so on have been widely explored .…”

Two Pathways of Thiolactone Incorporation into Polyurethanes and Their One-Pot Double Postfunctionalization

“…For this reason there is an increasing interest in considering PUs for advanced application fields like electronics, IT data storage, drug delivery, and transplantology (synthetic skin), among others. The properties and applications of PUs can be tuned by modification of the chemical nature and composition of di- or polyisocyanates and di- or polyols starting materials. ,, For many high-tech applications, PUs should have reactive groups to impart functionalities and tune their properties. − PUs can be functionalized by introducing functional groups onto diols prior to polymerization, by postpolymerization modification, or by a combination of both strategies. , Typically, a diol monomer with a protected amino or hydroxyl group is reacted with a diisocyanate, followed by deprotection to yield a PU with amino or hydroxyl groups for further functionalization. − Also, diols possessing pendant azide, alkyne, maleimido, or furyl groups were reported for the synthesis of PUs, which were subsequently modified via click reactions such as CuAAC, ,, thiol–maleimide, and thiol–yne coupling, or Diels–Alder reaction . Moreover, diols containing pentafluorophenyl ester, anthracene, , or allyl groups, reactive in subsequent click reactions, were also implemented in PU synthesis .…”