A series of poly(dodecafluoroheptyl methacrylate)-b-poly(methyl methacrylate) (PDFMA-b-PMMA) diblock copolymer nanoparticles were prepared by reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of methyl methacrylate (MMA) in supercritical carbon dioxide. Nuclear Magnetic Resonance (NMR) and gel permeation chromatography (GPC) analysis confirmed an efficient and wellcontrolled block copolymerization. As the length of the PMMA block grows from the soluble PDFMA block it eventually becomes insoluble, which drives in situ polymerization-induced self-assembly (PISA). The influences of the length of CO 2 -philic PDFMA block, CO 2 -phobic PMMA block and polymerization pressure were investigated in this PISA process. Also spherical nano-objects were formed upon the synthesis of amphiphilic diblock copolymers in situ. It appeared that, as the length of CO 2 -philic block PDFMA was increased, there was a corresponding decrease in particle size and particle size polydispersity. Scanning electron microscope (SEM) images revealed that, during the microspheres formation, the greater degree of polymerization (DP) of MMA favoured well-controlled monodisperse microspheres. a Reactions performed with [MMA] ¼ 0.8 M, [PDFMA-CDB] : [AIBN] ¼ 2 : 1, in 50 ml high-pressure autoclave at 70 C and 30 MPa for 24 h. b M n,th ¼ (([MMA] 0 )/[PDFMA-CDB] 0 ) Â M MMA + M PDFMA-CDB . c Gel permeation chromatography (GPC) in tetrahydrofuran with PS standards. dThe degree of polymerization (DP) for each polymer was calculated by the GPC. The degree of polymerization of the second block PMMA, DP nPMMA were determined by using the following formula: DP n ¼ [(M n of diblock copolymer PDFMA-b-PMMA À M n,NMR of PDFMA-CDB)/molecular weight of MMA monomer]. e Based on the visual observations made immediately aer the recovery of the polymers from the reactor, SB ¼ solid block, WP ¼ white powder. f D n ¼ particle size. g D w /D n ¼ size distribution. n.a.: not applicable.
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In this study, four environmentally friendly succinic acid double-tailed sulfonate fluorinated surfactants were synthesized from maleic anhydride, fluoroalkyl alcohols, namely 1-(1H,1H,7H-Dodecafluoroheptyloxy) ethanol, 1-(1H,1H,5H -octafluoropentyloxy) ethanol, 1-(1H,1H,3H-tetrafluoropropoxy) ethanol, and 1-(1H,1Htrifluoroethyoxy) ethanol, and sodium hydrogensulfite. The surfactant structure was characterized by FT-IR, 1 H NMR, and 19 F NMR . Thermogravimetric results showed that the fluorinated surfactants were stable up to relatively high temperature. The Krafft points of the four novel succinic acid double-tailed sulfonate fluorinated surfactants were all below 0°C. The lowest CMC value for the synthesized four double-tailed fluorine surfactants is about 0.076 mmol L -1 , far less than that of ammonium perfluorooctanoate (PFOA), demonstrating that double-tailed surfactants have higher surface activity than surfactants with one fluoroalkyl chain. The replacement of alkyl groups with oxyethylene groups enhances the hydrophilicity of the obtained fluorinated surfactants. Based on these findings, the synthesized surfactants may be environmentally friendly alternatives to PFOA and exhibit promising potential in industry applications.
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