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comparing the fluorescence channels of the copolymer for IPA- and BuOH-impregnated samples in Fig. 8e, h, respectively. It is also apparent, that in particular with H 2 O as a solvent there are almost no sleeves around fiber crossing points, which could yield a significant reinforcement of these fiber crossing- points, if in contact with water. Note, the use of dimethylacrylamide as the matrix monomer leads to a Fig. 7 CLSM cross-sectional images of an embedded paper sample, with the fluorescently labelled copolymer applied out of H 2 O( a – c ), IPA( d – f )andBuOH( g – i ), respectively, beforehand. The images show the cellulose fibers stained by CW ( a , d , g ), PDMAA labelled by RhB ( b , e , h ) and an overlay of the latter ( c ,
highly hydrophilic polymer, which can readily swell in water, even in the cross-linked state. Thus, we do see clear evidence for action of the copolymer/H 2 O system by the reinforcement mechanism, rather than by a protection mechanism. However, as is also evident from the structure analysis, the copolymers do not act purely on the reinforcement of fiber-crossing points but rather on the complete paper fiber. In the f , i ). The insets each show a magnification to highlight the spatial distribution of the RhB-labeled PDMAA across the fiber width and inside the fiber lumen. Scale bars are 100 and 20 l m for the overlay and insets, respectively. Overlays of both fluorescent signals appear as white
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