A Multiscale Modelling Framework for Adhesion, Etching and Ni Deposition in Cr(VI)-Free Metallization of Polymers

Developing sustainable alternatives to Cr(VI)-based metallization requires a mechanistic under-standing of adhesion, surface activation, and metal deposition across different length and time scales. Within the FreeMe project, we have es-tablished a unified multiscale modelling frame-work that links atomistic reactivity, interfacial behaviour, and mesoscale metal deposition phe-nomena relevant to Cr(VI)- and Pd-free Plating on Plastics (PoP).

Adhesion between polymer substrates and epoxy resins was characterised through classical Molec-ular Dynamics simulations. The methodology was first applied to PLA–epoxy systems and sub-sequently extended to ABS with different epoxy formulations, enabling the prediction of interfa-cial energies, resin penetration and structural or-ganization in relation to adhesion performance.

The chemical etching stage was analysed through complementary quantum and reactive simula-tions. Density Functional Theory calculations re-solved complete oxidation pathways for the ABS monomers, identifying feasible mechanisms and activation barriers for piranha-based etching. Re-active Molecular Dynamics (ReaxFF) simula-tions reproduced the dynamic interaction be-tween oxidants and the polymer surface, reveal-ing composition- and energy-dependent diffu-sion regimes, penetration depths and the evolu-tion of functional groups. Kinetic Monte Carlo simulations were used to extrapolate the oxida-tion patterns to longer times, predicting the tem-poral increase in surface energy associated with activation.

Finally, the deposition of nickel on etched ABS was investigated using a coarse-grained model, which captures mesoscale interactions between Ni species and the polymer surface. The model predicts Ni coverage as a function of temperature and pressure and identifies the dominant bead-level interactions governing deposition

This framework provides a predictive, SSbD-aligned toolset to support the design and optimi-sation of sustainable metallization processes for polymer substrates.