Small-angle X-ray scattering (SAXS). SAXS data were collected at the Beamline 4-2 of Stanford Synchrotron Radiation Lightsource. The distance between the sample and the detector (Pilatus3 X 1M) was 1.2 m and the energy of the Xrays was 11 keV (λ = 1.127 Å). Momentum transfer (q) was measured over a range of 0.01-0.75 Å -1 , where q is modulus of the scattering vector defined as follows: 𝑞 = 4𝜋𝑠𝑖𝑛𝜃 λ where θ = scattering angle, λ = wavelength of the X-rays.