Polythioethers with Controlled α,ω‐End Groups Prepared by Visible Light Induced Thiol–Ene Click Polymerization of Dithiol and Divinyl Ether with 4‐(N,N‐diphenylamino)benzaldehyde as Organocatalyst

Abstract

This study reports a step‐growth click‐polymerization of 1,4‐benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE) with 4‐(N,N‐diphenylamino)‐benzaldehyde (DPAB) as a photoredox catalyst under irradiation of visible light. DPAB exhibits a strong UV–vis absorption at 350 nm and a strong fluorescence emission at 480 nm in anisole. There is a strong fluorescence quenching between BDMT and DPAB. The molecular weight of the polythiolether can be controlled by reaction time and monomer feed ratios. More importantly, α,ω‐dithiol and α,ω‐divinyl telechelic polythiolether oligomers are successfully synthesized by simply changing the molar ratios of BDMT to DEGVE. 1H NMR and MALDI‐TOF MS spectra demonstrate that the oligomers have high end group fidelity. In addition, strong fluorescence is observed when the α,ω‐dithiol terminated polythiolether adds with N‐(1‐pyrenyl) maleimide, indicating that the as‐prepared polythiolether bears reactive thiol end groups. Furthermore, high molecular weight polythiolether are prepared by chain extension with reactive polythiolether oligomers as macro‐monomers. For example, α,ω‐divinyl oligomer (Mn = 2000 g mol−1) could further react with α,ω‐dithiol oligomer (Mn = 2400 g mol−1) to form high molecular weight polythiolether (Mn = 6000 g mol−1).

Semi‐Crystalline Poly(thioether) Prepared by Visible‐Light‐Induced Organocatalyzed Thiol‐ene Polymerization in Emulsion

“…The synthesis of low molecular weight telechelic poly(thioether)s was described using fac-Ir(ppy) 3 [12] and 4-(diphenylamino)benzaldehyde as photocatalyst. [13] Higher molecular weights and reaction rates were attained by Boyer [14] and Konkolewicz [15] through a different reaction mechanism involving an additional redox mediator, an amine, or alkyl halide respectively, which circumvents the slow rate of direct photooxidation of thiol with the photocatalyst. [16] To further expand the visible-light mediated photocatalytic thiol-ene polymerization, we describe herein an industrially relevant emulsion polymerization process to prepare linear poly(thioether) latexes in water using eosin-Y disodium (EY 2-) as photocatalyst, and leading after precipitation to semicrystalline polymers.…”

Surface engineering of Si wafers with tunable surface morphology and stiffness via visible light induced thiol‐ene click polymerization with 4‐(N,N‐diphenylamino)benzaldehyde as an organocatalyst

“…When excess of thiol monomers are added in the reaction system, the polythiolether with thiol end groups is produced. 28,30 The specific reaction with N-substituted maleimides (NMP) is a qualitative analysis method t of the thiol groups. 39 To verify the existing of reactive sulfhydryl groups in the grafted polymer layer, the N-(1-pyridyl)-maleimide (NPM) anisole solution was added onto the surface of the silicon wafer grafted with crosslinked polythiolether, and the fluorescence effect was observed after 12 h reaction.…”

“…43 Comparing with UV-light, visible light activated thiol-ene click polymerization is of negligible side reaction and ensures the high integrity of the -SH end groups. 28,30,44,45…”

“…29 Very recently, DPAB as a photoredox catalyst was also successfully used in synthesis of α,ω-dithiol and α,ω-divinyl telechelic polythioether oligomers through thiol-ene click polymerization of 1,4-benzenedimethane (BDMT) and diethylene glycol divinyl ether (DEGVE). 30 Thiol-ene click polymerization is of great advantage in surface modification for its insensitive to moisture and oxygen, and the availability of various functional monomers 31 These surface-anchored polymeric coatings demonstrate intrinsic properties of polymers, such as flexibility, biocompatibility, and stability. 32 With these unique and robust capabilities, novel reconfigurable surfaces, 33 bioactive materials, 25 and self-healing coatings 34 have been developed.…”

Direct Photolysis RAFT Polymerization of (Metha)acrylate with 2‐Cyano‐2‐propyldodecyl Trithiocarbonate as Mediator

“…[71] Recently, we have developed a series of aldehyde derivative catalysts, such as 4-methoxy benzaldehyde and 4-(N,N-diphenylamino) benzaldehyde, which can serve as effective photoredox catalysts for RDRP. [72][73][74][75][76] Compared to metal complexes, the polymerizations catalyzed with benzaldehydes are somewhat slow, and tertiary amine, such as N,N-dimethylaniline, could promote the polymerization significantly.…”