Graphene Modified Molecular Level And Its Application In The Field Of Drug Delivery

The unique two-dimensional, conjugated plane structure of graphene endow it with many super properties and various applications in many areas. However, the special structure of graphene also leads to many problems in the course of processing applications, such as poor dispersion, un-controlled conductivity. Molecular-level modification of graphene can solve these problems to some extent. Here we modified graphene via both covalent and non-covalent methods to prepare different kinds of graphene-polymer composite papers and graphene-PAA hydrogels. The conductive and drug release properties of materials were characterized. The main contents are as follows:In the first part, we summarized and compared the preparation of graphene, and also the modifications and applications of graphene, indicating the direction of development of preparation methods. Reversible fragmentation chain transfer (RAFT) polymerization methods were also introduced.In the second part, the diazonium salts and a small synthesized conjugated molecule were used to modify graphene in molecular level. Graphene conductive paper with tuned conductivity was prepared by a special way and the conductivity was controlled by different materials ratio. The results showed that the conductivity of as-prepared graphene paper ranges from0.1S/m to10000S/m.In the third part, we prepared graphene oxide with improved Hummers method, and stable reduced graphene dispersion reduced by hydrazine hydrate by adjusting the ratio of raw material. Pyrene-terminated RAFT agent was attached onto graphene surface via π-π stacking interaction followed by polymerization of various polymers. By controlling the type and the macromolecular chain length of attached polymers, we can also adjust the conductivity of graphene-polymer composite films.In the forth part, we studied the application of modified graphene for bimolecular materials. A pH-sensitive graphene/polymer hydrogel was prepared, which was used as drug loading and release carriers, and the results showed that the composite hygrogel has excellent mechanical properties and thermal stability. It also shows no toxicity to human cells and can be used to efficiently deliver drugs from acidic to neutral environment.