The polymerization reaction was carried out in a 500-ml four-necked, round-bottomed flask fitted with mechanical stirrer. Gelatin and distilled water were added to the flask to form a 0.5% (w/w) aqueous solution. An organic phase was prepared by mixing the monomer, the porogen and the initiator. The concentration of initiator was 1% by weight of the monomer, and the ratio of porogen to monomer was 2:1 (v/v). For the polymerization reaction, 120 ml of the organic phase was slowly added to 250 ml of the previously prepared gelatin aqueous solution under stirring at 45 ◦ C. The mix- ture was first slowly heated to 75 ◦ C and held at this temperature for 2 h, then heated to 85 ◦C and kept for 4 h and finally heated to 95 ◦C and held for 3 h. The resulting polymer beads were collected by fil- tration, followed by washing with hot water and extracting with acetone in a Soxhlet apparatus for 12 h before dried at 80 ◦ C for 8 h.