Bis-α,ω-bisacylphosphane oxides: simple access to crosslinked polymers with tunable properties

We present an efficient one-pot synthesis of bis-α,ω-bisacylphosphine oxides (Bis-BAPOs) obtained by coupling α,ω-dibromoalkanes with sodium bis(mesitoyl)-phosphide. The resulting tetrafunctional photoinitiators display absorption characteristics similar to the parent BAPO, yet allow pairwise, wavelength-selective activation. Stepwise irradiation at λ = 450 nm and λ = 385 nm triggers consecutive α-cleavage of the BAPO and the subsequently generated monoacylphosphane oxide (MAPO) moieties, enabling controlled polymer growth and branching. This strategy enables the preparation of hydrophilic, lipophilic, and amphiphilic polymer materials from standard monomers. Atomic force microscopy and contact-angle measurements reveal pronounced differences in surface chemistry despite homogeneous film morphologies, highlighting the impact of initiator architecture on interfacial properties. Migration analyses and photo-DSC experiments demonstrate that the molecular structure of the photoinitiator governs curing behaviour, conversion kinetics, and extractability, underscoring the potential of bis-BAPOs as tunable components for advanced photopolymer materials.