Photoinduced charge separation by chromophores encapsulated in the hydrophobic compartment of amphiphilic polyelectrolytes with various aliphatic hydrocarbons
摘要:
Terpolymers of 50 mol % sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS), 1 mol % 1-(pyrenylmethyl)methacrylamide (PyMAm), and 49 mol % lauryl- or cyclododecyl- or adamantylmethacrylamide units were synthesized. A copolymer of 99 mol % AMPS and 1 mol % PyMAm units was also prepared as a reference polymer. Charge-transfer (CT) complexation, fluorescence quenching, and photoinduced electron transfer (ET) were studied, using methylviologen (MV2+) as an acceptor. In the terpolymers, the polymer-bound pyrene (Py) chromophores are compartmentalized in hydrophobic microdomains of a micellelike microphase structure formed by the terpolymers in aqueous solution, while the chromophores are exposed to the aqueous phase in the reference copolymer. In the compartmentalized systems, the CT complexation of Py with MV2+ was suppressed, but the fluorescence quenching was enhanced. Charge recombination (CR) of the primary ion pair generated by laser excitation was slowed by an order of magnitude as compared to that in the reference copolymer system, while very fast photoinduced forward ET occurred (within ca. 20 ps). Thus, the terpolymer systems showed charge separation that persisted for hundreds of microseconds. These findings were qualitatively interpreted in terms of sterical protection of the Py chromophore from a close contact with MV2+, although MV2+ is highly concentrated on the surface of the hydrophobic microdomain of the terpolymers. A sterically hindered primary ion pair of a looser structure with a longer lifetime may be formed in the compartmentalized systems. The lauryl group was significantly less effective in protecting Py than were the cyclododecyl and adamantyl groups. A judicious choice of the hydrophobic group is suggested to achieve an optimal compartmentalization of Py, which will lead to an optimal efficiency for charge separation.
GRAFT COPOLYMER, METHOD FOR PRODUCING SAME AND RESIN COMPOSITION CONTAINING SUCH GRAFT COPOLYMER
申请人:Kaneka Corporation
公开号:EP1832613B9
公开(公告)日:2012-08-29
Graft Copolymer, Method For Producing The Same And Resin Composition Containing The Graft Copolymer
申请人:Saegusa Kazunori
公开号:US20080085975A1
公开(公告)日:2008-04-10
The present invention provides a novel graft copolymer and a resin composition that is excellent in the balance between flame retardancy and impact strength. Specifically, the present invention provides a polyorganosiloxane-containing graft copolymer comprising a polyorganosiloxane (A) segment, a polymer (C) segment having at least a unit derived from a nitrogen-atom-containing multifunctional monomer (B) having two or more radically polymerizable groups in its molecule, and a polymer (E) segment derived from an ethylenically unsaturated monomer (D) that has a glass transition temperature of 40° C. or higher, and a resin composition containing the graft copolymer.
Photoinduced charge separation by chromophores encapsulated in the hydrophobic compartment of amphiphilic polyelectrolytes with various aliphatic hydrocarbons
Terpolymers of 50 mol % sodium 2-(acrylamido)-2-methylpropanesulfonate (AMPS), 1 mol % 1-(pyrenylmethyl)methacrylamide (PyMAm), and 49 mol % lauryl- or cyclododecyl- or adamantylmethacrylamide units were synthesized. A copolymer of 99 mol % AMPS and 1 mol % PyMAm units was also prepared as a reference polymer. Charge-transfer (CT) complexation, fluorescence quenching, and photoinduced electron transfer (ET) were studied, using methylviologen (MV2+) as an acceptor. In the terpolymers, the polymer-bound pyrene (Py) chromophores are compartmentalized in hydrophobic microdomains of a micellelike microphase structure formed by the terpolymers in aqueous solution, while the chromophores are exposed to the aqueous phase in the reference copolymer. In the compartmentalized systems, the CT complexation of Py with MV2+ was suppressed, but the fluorescence quenching was enhanced. Charge recombination (CR) of the primary ion pair generated by laser excitation was slowed by an order of magnitude as compared to that in the reference copolymer system, while very fast photoinduced forward ET occurred (within ca. 20 ps). Thus, the terpolymer systems showed charge separation that persisted for hundreds of microseconds. These findings were qualitatively interpreted in terms of sterical protection of the Py chromophore from a close contact with MV2+, although MV2+ is highly concentrated on the surface of the hydrophobic microdomain of the terpolymers. A sterically hindered primary ion pair of a looser structure with a longer lifetime may be formed in the compartmentalized systems. The lauryl group was significantly less effective in protecting Py than were the cyclododecyl and adamantyl groups. A judicious choice of the hydrophobic group is suggested to achieve an optimal compartmentalization of Py, which will lead to an optimal efficiency for charge separation.