Structure of Polymer Rings in Linear Matrices: SANS Investigation

We have presented a systematic small angle neutron scattering investigation of ring–linear blends, where we vary either the ring volume fraction for given in long linear matrix or length at low fraction. found that radius gyration (Rg) shrinks with increasing and nearly reaches Rg melt ϕR = 0.5. At same time, fractal dimension, which is close to Gaussian conformation ϕR, decreases value melt. Aside from very short matrices, size independent host length. Following random phase approximation treatment, effective Flory–Huggins parameter (χF,RL) negative signifying attraction leads ring–ring repulsion. χF,RL decreasing size, might be related possibility threading events, when becomes smaller. The ϕR-dependent data cross-over regime between Q Porod ∼ Q–4 polymer RPA contribution displays an intermediate Q–2 regime, intensity increases proportional ϕR. origin this not clear but may critical fluctuations microphase separation induced by nonlocal positive χF,RL. experimental results fit well into general picture mainly based on simulations, even though detail, quantitative differences are obvious. Finally, our qualitative agreement earlier studies polystyrene blends.