Topology-Controlled Water Invasion in Hydrophobic Acrylic Polymer Networks for Intraocular Lens Materials: A Theory-Guided Design and Experimental Validation

Hydration-induced glistening remains a persistent challenge
in
hydrophobic acrylic intraocular lens (IOL) polymer networks despite
their low equilibrium water content. Here we establish a topology-controlled
water invasion framework that quantitatively links polymerization
chemistry, network topology, and solvent penetration behavior in cross-linked
polymer networks. By combining density functional theory (DFT) calculations
of radical polymerization mechanisms with all-atom molecular dynamics
simulations, we demonstrate that subtle differences in cross-linker
architecture and chain composition induce a topological transition
in free-volume connectivity and invasion free-energy landscapes. Networks
cross-linked by short EGDMA linkers exhibit a homogeneous distribution
of cross-linking points, nonpercolated free-volume cavities, and kinetically
stabilized polymer conformations, resulting in pronounced free-energy
barriers against water invasion. In contrast, BDDA-cross-linked networks
undergo chain-length-dependent inward aggregation and develop connected
free-volume pathways that facilitate solvent penetration. Nonequilibrium
tensile simulations further reveal that the same topology parameters
governing hydration resistance also influence the elastic stiffness
of the polymer networks, establishing a coupled structure–property
relationship between water invasion behavior and mechanical response.
Guided by these theoretical predictions, hydrophobic acrylic IOL polymer
networks were synthesized using EGDMA-based network architectures
and PEMA-rich compositions. The resulting polymer networks exhibit
significantly suppressed glistening formation under accelerated testing
conditions. Together, these results provide a molecular-level framework
for understanding hydration-induced defects in hydrophobic acrylic
IOLs and demonstrate how cross-linker architecture and network topology
can be rationally tuned to simultaneously regulate solvent invasion
and mechanical properties.