Synthesis And Characterization Of Star And Block Copolymers Based On PDMA And Their Solution Behaviors

This paper is focused on the synthesis and characterization of star and block copolymers based on poly[2-(N, N-dimethylamino)ethyl methacrylate] (PDMAEMA or PDMA in short) and their solution behaviors. The monomers used in this work include DMA, tert-butyl methacrylate (tert-BMA or tBMA) and 2, 2, 3, 3, 4, 4, 5, 5-octafluoropentyl methacrylate (OFPMA).(1) Fabrication of Microgels via Supramolecular Assembly of Polycation and PolyanionStar polymersβ-CD-g-PDMA was prepared by atom transfer radical polymerization (ATRP), while PMAA30-b-PEG-b-PMAA30 was synthesized by oxyanion-initiated polymerization. The composition and chemical structures of star polymer and block copolymer were confirmed by the measurements of 1H NMR spectroscopy, gel permeation chromatography (GPC), fourier transform infrared spectroscopy (FTIR) and thermogravity analysis (TGA). The self-aggregating morphologies of polyanion and polycation in aqueous solution were investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). It was found that the polycation and polyanion in phosphate buffer solution (PBS) formed microgel immediately as soon as they were mixed. The results of scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS) and rheological test confirmed the formation of polyion complex microgels. It was found that both the morphologies and particle size resulted from the microgels depended on the variation of concentrations, the structures of polyanion and the ratios of polycation to polyanion. (2) Preparation and Solution Behavior of Fluorinated Amphiphilic PolyelectrolyteWell-defined polyampholyte BzO-PDMA30-b-PMAA10-b-POFPMA6 was prepared successfully by the hydrolysis of fluorinated amphiphilic triblock copolymer BzO-PDMA30-b-PtBMA10-b-POFPMA6, which was synthesized by oxyanion-initiated polymerization. The composition and chemical structure of these fluorinated copolymers were confirmed by 1H NMR, 19F NMR spectroscopy and gel permeation chromatography (GPC) techniques. The solution behaviors of these fluorinated copolymers were investigated by the measurements of surface tension, dynamic light scattering (DLS), Zeta-potential (ξ-potential) and transmission electron microscopy (TEM). The results indicate that the BzO-PDMA30-b-PMAA10-b-POFPMA6 possess relatively high surface activity than BzO-PDMA30-b-PtBMA10-b-POFPMA6. Moreover, the DLS andξ-potential measurements showed that these two kinds of fluorinated triblock copolymers possess distinct pH-responsive properties.