基于双分子亲核取代反应海藻酸苄酯衍生物的制备与性能

Preparation and Performances of a Benzyl Alginate Derivative via a Bimolecular Nucleophilic Substitution Reaction

以溴化苄（BnBr）为疏水改性剂,采用双分子亲核取代反应（SN2）制备了海藻酸苄酯衍生物（BAD）。通过FTIR、1HNMR、TGA、UV-Vis、GPC、DLS和Zeta电位分析表征了BAD的结构和性能。结果表明：所得产物取代度接近于溴化苄与糖醛酸的投料比,说明SN2反应活性高、取代度大。改性后,BAD相对分子质量（Mw）由91544降低至79819。在水热驱动作用下BAD形成的胶束聚集体水动力学粒径（dH）为423.4 nm,Zeta电位值为-36.4 mV。并且随pH的增大,其Zeta电位有不断降低的趋势,而dH先升高后降低。随离子强度的增大,dH和Zeta电位都出现先升高后降低的趋势,因此,BAD有一定的胶体界面活性。

Benzyl alginate derivative（BAD） was prepared by a bimolecular nucleophilic substitution reaction（SN2） using benzyl bromide（BnBr） as hydrophobic modifier. Its structure and performances were characterized by FTIR, 1 HNMR, TGA, UV-Vis, GPC, DLS and Zeta potential. Experimental results showed that the degree of substitution of the obtained product was close to the molar ratio of benzyl bromide to uronic acid, indicating that the activity of SN2 reaction was high and the degree of substitution of BAD was large. After modification, the molecular weight（Mw） of BAD decreased from 91544 to 79819. BAD could form micellar aggregates under hydrothermal driving forces. The hydrodynamic diameter（dH） and Zeta potential value of BAD micelles were 423.4 nm and-36.4 mV, respectively. Furthermore, with the increase of pH, the Zeta potential tended to decrease, while the dH initially increased and then decreased. Meanwhile, when the ionic strength increased, both dH and Zeta potential showed a tendency to increase first and then decrease. Therefore, BAD exhibited certain colloidal and interfacial activity.