Multilayer films were built on four different substrates: silicon wafers (Si), polystyrene (PS), polypropylene (PP) and Teflon (PTFE). Prior to film deposition, they were cleaned with ethanol and rinsed thoroughly with water before being dried with a stream of nitrogen. The polyelectrolyte solutions were freshly prepared at various concentrations (1, 3, or 5 mg/mL). For the adjustment of pH, an acetate buffer was prepared at pH 3 or 5 using appropriate volumes of 0.1 M acetic acid and 0.1 M sodium acetate. Solutions were prepared in this buffer (in the absence of additional salt) or in the presence of 0.15 M NaCl at pH 5.5. The different conditions tested are named using the following nomenclatures: (CHI/ALG) cC/cA pH pHC/pHA where cC and cA represent the concentration of CHI and ALG, respectively and pHC and pHA represents the pH of CHI and ALG, respectively. For example, a film built with CHI (1 mg/mL, pH 5) and ALG ( 5 mg/mL, pH 3) is noted CHI/ALG 1/5 pH 5/3.
The substrates were first dipped in the CHI solution for 5 min then rinsed twice in water (with the same pH as the CHI solution) for 2 min. Subsequently, they were immersed in ALG solution for 5 min followed by rinsing twice in water (with the same pH as the ALG solution) for a period of 2 min. This procedure was repeated until the desired number of layer pairs was achieved to prepare the (CHI/ALG)i multilayer films, being i the number of layer pairs.
The substrates were first dipped in the CHI solution for 5 min then rinsed twice in water (with the same pH as the CHI solution) for 2 min. Subsequently, they were immersed in ALG solution for 5 min followed by rinsing twice in water (with the same pH as the ALG solution) for a period of 2 min. This procedure was repeated until the desired number of layer pairs was achieved to prepare the (CHI/ALG)i multilayer films, being i the number of layer pairs.
