Department of Chemical Engineering, McMaster University, Hamilton, Canada.
Biomacromolecules. 2011 Apr 11;12(4):942-8. doi: 10.1021/bm200101b. Epub 2011 Mar 10.
Described is a new, greener approach to increasing adhesion between wet cellulose surfaces. Polyvinylamine (PVAm) with grafted TEMPO spontaneously adsorbs onto cellulose and oxidizes the C6 hydroxyl to aldehyde groups that react to form covalent bonds with primary amines on PVAm. Grafted TEMPO offers two important advantages over solutions of low-molecular-weight water-soluble TEMPO derivatives. First, the oxidation of porous cellulose wood fibers is restricted to the exterior surfaces accessible to high-molecular-weight PVAm. Thus, fibers are not weakened by excessive oxidation of the interior fiber wall surfaces. The second advantage of tethered TEMPO is that the total dose of TEMPO required to oxidize dilute fiber suspensions is much less than that required by water-soluble TEMPO derivatives. PVAm-TEMPO is stable under oxidizing conditions. The oxidation activity of the immobilized TEMPO was demonstrated by the conversion of methylglyoxal to pyruvic acid.
描述了一种提高湿纤维素表面之间附着力的新的、更环保的方法。接枝 TEMPO 的聚乙烯亚胺（PVAm）自发吸附在纤维素上，并将 C6 羟基氧化为醛基，与 PVAm 上的伯胺反应形成共价键。与低分子量水溶性 TEMPO 衍生物的溶液相比，接枝 TEMPO 具有两个重要优势。首先，多孔纤维素木纤维的氧化仅限于可及高分子量 PVAm 的外表面。因此，纤维不会因内部纤维壁表面的过度氧化而变弱。TEMPO 键合的第二个优点是，氧化稀纤维悬浮液所需的 TEMPO 总量远远小于水溶性 TEMPO 衍生物所需的 TEMPO 总量。PVAm-TEMPO 在氧化条件下稳定。固定化 TEMPO 的氧化活性通过将甲基乙二醛转化为丙酮酸来证明。
