Multi‐Scale Structural Insights Into Amphiphilic Model PEG–PCL Co‐Networks From LS and SANS

ABSTRACT This work investigates the structural characteristics of model amphiphilic polymer co‐networks formed by hetero‐complementary crosslinking of 2‐(4‐nitrophenyl)‐benzoxazinone‐terminated tetra‐poly(ε‐caprolactone) (t‐PCL) and amino‐terminated tetra‐poly(ethylene glycol) (t‐PEG) in nonselective and selective solvents using simultaneous dynamic and static light scattering (DLS & SLS) and small‐angle neutron scattering (SANS). In addition, time‐resolved dynamic light scattering (TRDLS) is employed to follow the real‐time gelation in a nonselective solvent. Simultaneous DLS/SLS measurements yield dynamic and static correlation lengths, providing insight into thermally driven and frozen‐in concentration fluctuations, respectively. The static correlation length increases with the polymer volume fraction, indicating growing structural inhomogeneities arising from partial PEG/PCL immiscibility, while the mean‐square refractive index fluctuations decrease, suggesting reduced local contrast and enhanced overall homogeneity. In contrast, the dynamic correlation length decreases with increasing polymer volume fraction according to ξ ∼ Φ −0.95 ± 0.15 , consistent with faster cooperative segmental dynamics. Complementary SANS measurements on water‐swollen APCNs confirm the presence of microphase‐separated PCL clusters, well described by a polydisperse Percus–Yevick hard‐sphere model with consistent core–corona architecture independent of the network polymer volume fraction at preparation. Comparison with a purely hydrophilic PEG–PEG reference network highlights the influence of amphiphilicity on the structural features of the networks.