1. National Centre for Nano-Structured Materials, Council for Scientific and Industrial Research, 1-Meiring Naude
Road, Brummeria, Pretoria 0001, South Africa
2. Division of Polymer Technology, Department of Chemical, Metallurgical & Materials Engineering, Tshwane University of Technology, Pretoria 0001, South Africa
3. Department of Applied Chemistry, University of Johannesburg, Doornforntein 2028, Johannesburg,
South Africa