Preparation and self-assembly of pH-sensitive amphiphilic comb-shaped copolymer containing long fluorinated side chains

ABSTRACT

Novel pH-sensitive amphiphilic comb-shaped copolymers containing long fluorinated side chains, which combined the characteristics of pH-sensitivity from pendent tertiary amine groups, unique hydrophobic and fluorophobic characteristic from the fluorinated moieties and hydrophilicity from the poly (ethylene glycol) segments, were designed and synthesized via radical polymerizaion of 2-(Dimethylamino) ethyl methacrylate (DMAEMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA) and homemade fluorinated macromonomer (PHFBMA-GMA). The physicochemical properties of polymeric micelles prepared therefrom were investigated. The chemical structures of the copolymers were characterized by GPC, FTIR and ¹H-NMR. The critical micelle concentrations (CMC) of the copolymers in different pH (5.0 and 7.4) were determined by fluorescence spectroscopy. Larger CMCs could be obtained in lower pH since the pronation of DMAEMA moieties enhanced the hydrophilicity. With increasing the amount, as well as the molecular weight, of PHFBMA-GMA, CMC decreased significantly. As pH decreased, particle size, as well as zeta potential of the polymeric micelles increased significantly, indicating significant pH-sensitivity of the polymeric micelles. Furthermore, larger polymeric micelles were obtained with larger amount, as well as higher molecular weight, of PHFBMA-GMA. Transmission electron microscopy (TEM) showed that the morphological shapes of the copolymers performed spherical micelles. The cytotoxicity test showed that the comb-shaped copolymers performed extremely low cytotoxicity. The pH-sensitive polymeric micelles prepared from the amphiphilic comb-shaped copolymers containing long fluorinated side chains could be potential candidates for nanotanks for hydrophobic or fluorophobic molecules and drug carriers and the facile preparation might fit for large scale industrialization.

KEYWORDS:

• pH-sensitive
• amphiphilic comb-shaped copolymer
• self-assembly
• fluorinated side chains
• cytotoxicity

Funding

This study was supported by the Key Laboratory of Cellulose and Lignocellulosics, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, Provincial Science and technology project of Guangdong Province (No.2015B090925019), Guangzhou Municipal Science and Technology Program (No.201509010019) and Specific Project of Guangzhou Pearl River Star of Science and Technology (No. 201610010133)