Water soluble poly(styrene sulfonate)--poly(vinylidene fluoride)--poly(styrene sulfonate) triblock copolymer nanoparticles

• Published in: RSC advances 2016-06, Vol.6 (6), p.55374-55381
• Main Authors: ernoch, Peter, ernochová, Zulfiya, Petrova, Svetlana, Ka ková, Dana, Kim, Joon-Sung, Vasu, Vignesh, Asandei, Alexandru D
• Format: Article
• ISSN: 2046-2069
• DOI: 10.1039/c6ra10241g

A visible light, Mn 2 (CO) 2 -photomediated process was used to enable the iodine degenerative transfer controlled radical polymerization of vinylidene fluoride (VDF) initiated from I-(CF 2 ) 6 -I, and the successive quantitative activation of the ∼CH 2 -CF 2 -I and ∼CF 2 -CH 2 -I chain ends of I-PVDF-I, to produce a series of PNpSS- b -PVDF- b -PNpSS triblock copolymers (NpSS/VDF/NpSS = 4/60/4, 15/60/15, 34/60/34) with neopentyl styrene sulfonate (NpSS), which upon NaN 3 deprotection, afforded the corresponding PNaSS- b -PVDF- b -PNaSS. All blocks, as well as PVDF, PNpSS and PNaSS formed water stable dispersion/solutions following either nanoprecipitation from acetone (PVDF, PNpSS, and PNpSS- b -PVDF- b -PNpSS) or direct dissolution in water (PNaSS, PNaSS- b -PVDF- b -PNaSS). Remarkably, all PNaSS- b -PVDF- b -PNaSS triblocks also provided indefinitely stable systems even under the high ionic strength conditions of phosphate buffered saline (PBS) solutions, corresponding to cell-isotonic, pH = 7.4 conditions. These trends were found to be consistent with the block composition dependence of the apparent hydrodynamic radius ( R h ), conductivity, and zeta potential ( ζ ), where R h increases upon deprotection from about 35-25 nm to about 168-136 nm in water, and decreases to 133-86 nm in PBS solutions, ζ decreases from ∼−40 mV to ∼−70 mV in water and increases to ∼−18 mV in PBS, and where the conductivity is negligible for PNpSS- b -PVDF- b -PNpSS but then increases linearly to ∼0.2 mS cm −1 for PNaSS- b -PVDF- b -PNaSS in water to reach ∼17 mS cm −1 in PBS. Finally, the blocks were evaluated as promising 19 F-MRI contrast agents. Water-soluble PNaSS- b -PVDF- b -PNaSS triblock copolymer.