PPEGMEA-g-PDEAEMA全亲水接枝共聚物的合成及其 包埋甲氨喋呤体外控释的研究

以聚乙二醇丙烯酸酯(PEGMEA)为起始原料, 将原子转移自由基聚合(ATRP)技术和从主干接枝(grafting-from)策略相结合, 合成了结构规整的聚甲基醚聚乙二醇丙烯酸酯-g-聚(N,N’-二乙基胺乙基甲基丙烯酸酯) (PPEGMEA-g- PDEAEMA)接枝共聚物. 这种接枝共聚物通过静电作用形成胶束包埋甲氨喋呤(MTX), 得到具有98.7%高包封率的药物载体, 体外药物释放得到很好的控制.     

PPEGMEA-g-PMAA全亲水接枝共聚物包埋甲氨喋呤体外控释的研究

以全亲水接枝共聚物PPEGMEA-g-PMAA为载体材料,以甲氨喋呤(MTX)为模型药物,通过物理包埋和化学键合法制备MTX药物缓释体系,探讨了pH值、制备方法等对载药量、包埋率和释药行为等的影响,两种体系均可以通过改变pH值来控制药物的释放和释放速率。     

Weakening effect of plastic yielding inception in thin hard coating systems

Hard coatings have been widely applied to enhance tribological performance of mechanical components.However,it was predicted that thin hard coatings may have a weakening effect which could reduce the coating/substrate system’s resistance to plastic yielding compared with the uncoated substrate material.In this paper,analytical simulation is utilized to investigate the origin of weakening effect.The functions of material mechanical properties and coating thickness on the weakening effect are theoretically investigated.Partial-unloading spherical nanoindentation tests are performed on tungsten coated single crystalline silicon and copper to acquire the stress-strain curves and compared with the uncoated cases.The experimental results are in consistence with the analytical solutions,demonstrating the presence of weakening effect.