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 Performance of Benzyl Alginate Derivatives via Bimolecular Nucleophilic Substitution Reaction

摘要:

以溴化苄为疏水改性剂，采用双分子亲核取代反应(SN2)制备海藻酸苄酯衍生物(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(49.21 %和29.33 %)接近于投料比，说明SN2反应活性高，取代度大。改性后，BAD分子量(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。

Abstract:

Benzyl alginate derivative (BAD) was prepared by bimolecular nucleophilic substitution reaction (SN2) using the benzyl bromide as a hydrophobic modifier. The structure and performance of BAD was characterized by FTIR, 1HNMR, TGA, UV-Vis, GPC, DLS and Zeta potential analyzer. Experimental results showed that the degree of substitution of the obtained product (49.21 % and 29.33 %) was close to the molar ratio of benzyl bromide to uronic acid, indicating that SN2 reaction was active with large degree of substitution. After modification, the molecular weight (MW) of BAD decreased from 91544 to 79819. And the micellar aggregates were formed by BAD under hydrothermal driving forces with the hydrodynamic diameter (dH) as 423.4 nm and the zeta potential value as -36.4 mV. Furthermore, with the increase of pH, the Zeta potential of BAD tended to decrease, while its hydrodynamic size (dH) firstly increased and then decreased. Meanwhile, with the increase of ionic strength, the dH and Zeta potential of BAD firstly increase and then decrease, which revealed that BAD may possess certain colloidal and interfacial activity.