Polyurethanes, containing well-defined assemblies of perfluoro-polyether (PFPE or hexafluoropropene oxide oligomer), polydimethylsiloxane (PDMS), and polyethylene glycol (PEG) segments, exhibit oleophobic, hydrophobic, and hydrophilic properties in response to the polarity of the contacting medium. These polymers were prepared by reacting hydroxy(polyethyleneoxy)-propylether-terminated PDMS block copolymer (HO-PEG-PDMS-PEG-OH) with 4,4'-methylene-bis(phenylene isocyanate) (MDI) in the presence of dibutyltin dilaurate catalyst, followed by reaction with 1,2-diol functional PFPE and chain extension with 2,2,3,3-tetrafluoro-1,4-butanediol (FB). The oleophobic and hydrophobic properties of the segmented polyurethanes (SPU) are due to the segregation of PFPE segments at the polymer-air interface. Wettability studies revealed that the same surface becomes hydrophilic, presumably due to the segregation of the PEG segments at the polymer-water interface. This hydrophobic-to-hydrophilic transformation of the surface prevails not only when the polymer is in contact with liquid water but with water vapor as well. The understanding of the reconstruction mechanism of this novel family of SPU surfaces would furnish valuable information for various applications where dynamic transformation of surface activity is desired.

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Synthesis and surface properties of environmentally responsive segmented polyurethanes.

Synthesis of self-assembled fluoroalkyl end-capped oligomeric aggregates: Applications of these aggregates to fluorinated oligomeric nanocomposites

The purpose of this study was to evaluate the inhibition of biofilm formation on newly developed coating materials with self-cleaning properties. A series of experimental coating materials containing fluoroalkylated acrylic acid oligomer (FAAO) were applied to resin composite substrates. The surfaces of the coating materials were analyzed by X-ray photoelectron spectroscopy (XPS) and contact angle measurement. Biofilm formation on the surface was assessed using Streptococcus mutans biofilms inside an oral simulator in vitro. The results indicated that an increase in the concentration of FAAO in the coating materials enhanced surface hydrophilicity and oil-repellency. Biofilm assays demonstrated that the amount of biofilm retained on the coating materials gradually decreased when the concentration of FAAO increased in the materials. It was concluded that the coating materials incorporated with FAAO possessed self-cleaning properties and displayed signs of inhibiting biofilm formation on their surfaces.

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Inhibition of Biofilm Formation using Newly Developed Coating Materials with Self-cleaning Properties

Fluoroalkanoyl peroxide [RF-C(=O)OO(O=)C-RF] decomposes homolytically through concerted three bond radical fission to afford fluoroalkyl radical (RF·) selectively, although the corresponding alkanoyl peroxide [R-C(=O)OO(O=)C-R] decomposes homolytically through stepwise radical fission to afford acyloxy radical [R-C(=O)O·] and alkyl radical [R·]. This decomposition of fluoroalkanoyl peroxide was applied to the direct fluoroalkylation of two end-sites of vinylsilane oligomers and (meth)acrylate oligomers. Fluoroalkyl end-capped trimethoxyvinylsilane oligomers [RF-(CH2CHSi(OMe)3)n-RF] thus obtained were applied to the surface modification on glass and traditional organic polymers such as PMMA and rubbers to exhibit not only strong hydrohobicity but good oleophobicity imparted by fluorine with extremely higher adhesive property on their surface. Fluoroalkyl end-capped actylate and methacrylate oligomers exhibited surface active properties imparted by fluorine, the same as for low-molecular weight fluorinated surfactants, and these fluorinated cooligomers formed the nanometer size-controlled self-assembled molecular aggregates in aqueous and organic media. These fluorinated molecular aggregates interacted with a variety of guest molecules such as low molecular biocides, fullerenes, and carbon nanotubes to afford the corresponding fluorinated oligomers/guest molecules nanocomposites. These fluorinated oligomers were applied to the preparation of fluorinated oligomers/silica gel nanocomposites and cross-linked fluorinated oligomeric nanoparticles.

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Development of Fluorinated Polymeric Functional Materials Using Fluorinated Organic Peroxide as Key Material

Preparation and applications of novel fluoroalkyl end-capped oligomeric nanocomposites

The reactions of acrylic acid with various of difluoroalkanoyl peroxides {(RfCO2)2, Rf= C3F7, C6F13 CF(CF3)[OCF2CF(CF3)]mOC3F7, m= 0, 1, 2} have been found to give new fluoroalkylated oligomers containing carboxy groups {Rf[CH2CH(CO2H]nRf} under mild conditions, and these compounds are able to reduce the surface tension of water to 10 mN m–1 levels

Synthesis and surfactant properties of fluoroalkylated oligomers containing carboxy groups

Reactions of fluoroalkanoyl peroxides [RFCO2O2CRF, RF=C3F7, C6F13, CF (CF3) OC3F7, CF (CF3) OCF2CF (CF3) OC3F7] with vinylsilanes [R3SiCH=CH2, R=CH3, OCH3, OC2H5] and allylsilanes [R3SiCH2CH=CH2, R=CH3, OCH3, OC2H5, OSi (CH3) 3] were studies, Fluoroalkyl radicals (RF·), produced by the thermal decomposition of fluoroalkanoyl peroxides, added to vinylsilanes to give fluorine-containing silicon oligomers [RF- (CH2-CHSiR3) n1-RF, n1=2, 3]. Allylsilanes reacted with fluoroalkanoyl peroxides to give 1 : 1 adducts [R3SiCH2CH (OCORF) CH2RF] without oligomer formation.The synthesis of these new fluorine-containing silicon compounds is possible under very mild conditions (3040°C) to give excellent to moderate yields. Products bearing alkoxy groups were found particularly useful for surface active substances and have good water-and oil-repellency.

Synthesis and Properties of Fluorine-Containing Organosilicon Compounds by the Reactions of Vinyl- and Allylsilanes with Fluoroalkanoyl Peroxides

Reactions of fluoroalkanoyl peroxides with organosilicon compounds

Fluoroalkylated oligomers with carbon-carbon bond formation were obtained by reactions of acrylic acid, methyl methacrylate, and ethylene oxide units-containing methacrylates, acrylates with fluoroalkanoyl peroxides in excellent to moderate yields under very mild conditions. A mechanistic study of these reactions was carried out by the MNDO-PM 3 semiempirical MO method. A strong interaction between HOMO of the monomer and SOMO of fluoroalkyl radical produced by the thermal decomposition of the peroxide appeared to cause the addition of the fluoroalkyl radical, to the monomer to afford the corresponding fluoroalkylated oligomer. Fluoroalkylated acrylic acid oligomers were found capable of reducing the surface tension of water to 10 mN/m. Fluoroalkylated-methacrylates, and-acrylates oligomers containing ethylene oxide units became typical fluorinated amphipathic compounds.

Synthesis and Properties of the Fluoroalkylated Oligomers with Carbon-Carbon Bond Formation

New fluorosilicone co-oligomers were obtained by reactions of fluoroalkanoyl peroxides with trimethoxyvinylsilane and methacrylate monomers containing poly (oxyethylene) units. The cooligomers were found useful as amphiphilic fluorosilane coupling agents.

Yue-Fa Gong

Papers

Synthesis and surfactant properties of fluoroalkylated oligomers containing carboxy groups

Synthesis and Properties of Fluorine-Containing Organosilicon Compounds by the Reactions of Vinyl- and Allylsilanes with Fluoroalkanoyl Peroxides

Reactions of fluoroalkanoyl peroxides with organosilicon compounds

Synthesis and Properties of the Fluoroalkylated Oligomers with Carbon-Carbon Bond Formation

Synthesis and Surface Properties of Novel Amphiphilic Fluorosilicone Oligomers