Novel photoacid generators for cationic photopolymerization

Abstract

Novel cationic photoinitiators based on the non-nucleophilic [Al(OC(CF3)3)4]− anion were prepared and their high efficiency was presented in comparison to benchmark systems.

Carbon Dots as a Promising Green Photocatalyst for Free Radical and ATRP‐Based Radical Photopolymerization with Blue LEDs

“…This thermodynamic quantity indicates sufficient generation of initiating radicals in the sensitized free radical polymerization . The selected anions were aluminates ( a ) and bis(trifluoromethylsulfonyl) imides ( b ) to maintain the advantages of the initiator disclosed previously . These anions have received increasing attention as the counterions of onium salts because they do not generate HF, which can arise from the PF 6 − anion under certain conditions (see refs .…”

“…[14] They assume the function of ap hotosensitizer in combination with radical initiators such as onium salts. [17] In particular, iodonium salts and sulfonium salts comprising low-coordinating anions have received increased attention. [17] According to the electrochemical properties reported previously, [14] CDs may also assume am ajor function in photo-ATRP protocols,a s previously reported for metal-free systems [8] and Cu II -catalyzed systems,which required aheavy metal concentration in the ppm range.…”

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

“…Ther eaction between the corresponding diols and PCl 5 proceeds with evolution of five equivalents of HCl and the last proton is then transferred to the Et 2 Os olvent to form the desired [H(OEt 2 )][WCA]s alt. [281] [H(OEt 2 ) 2 ][B(Ar CF3 ) 4 ]w as also used to protonate the monomeric ring-expanded carbene gold hydride complexes [283,284] The use of am ore weakly coordinating anion has two benefits: 1) it generates as tronger acid upon irradiation to initiate polymerization and 2) cation-anion interactions during polymerization are reduced to give amore active catalyst. [183] Oxonium acids have also featured highly in the literature for the protonolysis of metal/main group element-carbon bonds to yield the corresponding cation supported by the WCA.Amultitude of examples are presented in areview on p-block cations.…”

“…[ 4 ]salt is readily prepared, stable at room temperature for more than ay ear, and introduces the very weakly coordinating [Al(OR F ) 4 ] À anion. [284] 3.4. [275] Moreover, whilst original reports of the preparation of [(C 5 Me 5 )Si)] + from the corresponding silicocene Si(C 5 Me 5 ) 2 supported by the [B(C 6 F 5 ) 4 ] À WCA required the use of the rather bespoke Brønsted acid [C 5 Me 5 H 2 ] + , [276] the same reaction using [H-(OEt 2 ) 2 ][Al(OR F ) 4 ]a st he Brønsted acid also furnishes the highly pure [(C 5 Me 5 )Si)] + cation.…”

1,2‐Diketones as photoinitiators of both cationic and free‐radical photopolymerization under UV (392 nm) or Blue (455 nm) LEDs

“…More interestingly, the similar CQ‐based PIS (CQ/iodonium salt (i.e.,[4‐[octyloxy]phenyl]phenyliodonium hexafluoroantimonate)/EDB) was reported for the polymerization of epoxide under blue light conditions for an additive manufacturing approach (i.e., solution mask liquid lithography) . Recently, an increasing number of novel PISs have been emerging and exhibited high efficiency for free‐radical and/or cationic photopolymerization under visible light . These novel PISs are mainly synthesized with designated chemical structures.…”