SUPPORTING INFORMATION Electrospinning Polyelectrolytes Complex: pH Responsive Fibers

Methods Rheology Discovery DHR-2 rotational rheometer (TA Instruments, USA) was used for investigation of rheological properties of the solutions under steady-state shear deformation. Cone-plate geometry with diameter of 40 mm and the angle at cone tip of 1° was applied. All tests have been carried out at 23 °C. HRSEM and cryo-HRSEM A single fiber was collected onto a specially designed SEM sample holder comprising a conducting trench and was adhered to the sides of the trench. In order to compare between the dry and the swollen state of the fibers, we performed RT HR-SEM imaging prior to cryo HR-SEM imaging. For cryo-SEM specimen preparation, as spun fibers were immersed into water at predetermined pH. After 3 min of swelling, the water excess was removed with a filter paper, and the sample was quenched into liquid ethane at its freezing temperature. After vitrification the sample holder was mounted onto a sample-table for cryo-HR-SEM imaging (Leica AG. Liechtenstein), and was transferred Electronic Supplementary Material (ESI) for Soft Matter.