期刊
LANGMUIR
卷 33, 期 32, 页码 7854-7861出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.langmuir.7b01460
关键词
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资金
- BASF Canada
- Canadian Foundation for Innovation
The structure and electrochemical properties of adsorbed complexes based on mixtures of polyvinylamine-g-TEMPO (PVAm-T) and laccase were related to the ability of the adsorbed complexes to oxidize cellulose. PVAm-T10 with 10% of the amines bearing TEMPO moieties (i.e., DS = 10%), adsorbed onto gold sulfonate EQCM-D sensor surfaces giving a hydrogel film that was 7 nm thick, 89% water, and encasing laccase (200 mM) and TEMPO moieties (33 mM). For DS values >10%, all of the TEMPOs in the hydrogel film were redox-active in that they could be oxidized by the electrode. With hydrogel layers made with lower-DS PVAm-Ts, only about half of the TEMPOs were redox-active; 10% DS appears to be a percolation threshold for complete TEMPO-to-TEMPO electron transport. In parallel experiments with hydrogel complexes adsorbed onto regenerated cellulose films, the aldehyde concentrations increased monotonically with the density of redox-active TEMPO moieties in the adsorbed hydrogel. The maximum density of aldehydes was 0.24 mu mol/m(2), about 10 times less than the theoretical concentration of primary hydroxyl groups exposed on crystalline cellulose surfaces. Previous work showed that PVAm-T/laccase complexes are effective adhesives between wet cellulose surfaces when the DS is >10%. This work supports the explanation that TEMPO-to-TEMPO electron transport is required for the generation of aldehydes necessary for wet adhesion to PVAm.
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