Agar-glycerol-based gels, hydrogels and organo-hydrogels synthesis

Agar-glycerol-based gel and hydrogels were synthesized via free radical polymerization in emulsion according to the preparation method given in Table ​Table11 [6]. Gel and hydrogels were synthesized as described by Alpaslan et al. (2021). Gel and hydrogel compositions are given in Table ​Table2.2. Free radical polymerization in emulsion media method was used to synthesis the Agar-Glycerol-based [6] organo-hydrogels given in Table ​Table1.1. Briefly, firstly, 2 mL of agar solution and 0.04 mL of glycerol were added to the 20-mL flask and made homogeneous by vigorous mixing (at 2500 rpm). Secondly, of different amounts (0.1, 0.2 and 0.3 mL) garlic oil was added in the reactions mixture. The organo-hydrogel mixture was stirred at 800 rpm for 15 min until the formation of a clear homogeneous solution emulsion. Thirdly, MBA (0.1%) or glutaraldehyde reagent was added as a crosslinker and further homogenized. Organo-hydrogel compositions are given in Table ​Table2.2. In the synthesis, strong hydrogen bonds were formed between the -OH groups on garlic oil and glycerol molecules and the -OH groups in the agar structure and at same time crosslinking agent was added to the reaction medium, resulting in crosslinking between garlic oil, agar and glycerol (Kim et al. 2010; Singh et al. 2015; Xia et al. 2011). Finally, the polymerization reaction was initiated by the addition of the initiator solution APS in 100 µL DI water. Reaction temperatures were maintained at 25 °C with a temperature-controlled hot plate. Then, the solution was transferred into a pipet with 6 mm diameter and was allowed to polymerize for 4 h. and cut into 6 mm long cylinders. These preparation steps are schematically given in Fig. 1. The gel, hydrogels and organo-hydrogels were kept in DI water, which was renewed every 2 h for 8 h to eliminate unreactive monomers. Finally, the synthesized gel, hydrogels, p(AG-m-GO) and p(AG-g-GO) organo-hydrogels were dried in the oven at 40 °C until a constant weight was achieved and stored at 4 °C for further uses.

Codes of different organo-hydrogels

Compositions and codes of different organo-hydrogels

Synthesis and schematic presentation of organo-hydrogels