A Novel Method To Synthesize Polymer Brushes Based On The Hydroxyapatite Particles

In this paper, polymethyl methacrylate brushes synthesized via atom transfer radical polymerization based on hydroxyapatite were investigated. Polymers grafted onto solid substrates have attracted much attention in the recent past as a novel method to modify surface owing to its potential applications. And the the advent of atom transfer radical polymerization as a controlled means to synthesize polymer from a wide range of monomers with low polydispersity has been used for the preparation of polymer brushes. To date, a variety of substrates, including silicon wafers, silica, gold particles and copper have been prepared."Grafting to"or"grafting from"are major approaches for preparation of polymer brushes. One of the disadvantages about"grafting from"approach, however, is that the grafting reactions are hard to quantify. To well control the molecular weight of grafting segments, a different strategy is applied in the studies. There are three steps to build the brushes, which are synthesis of the PMMA-Br, HA surface pretreatment and preparation of polymer brush. Chapter Two of this paper focuses on the synthesis of macroinitiator. Chapter Three of this paper focuses on the way of HA surface pretreatment; the pH value of methanol-distilled water solution was adjusted with glacial acetic acid to catalyze the hydrolysis of the methoxyl groups of the silanes. As the hydrolysis and silanol formation ended, the HA powders were silanized by stirring them in solution. With the reaction ended the pH value was increased with 10% NaOH solution to encourage condensation and formation of siloxane network. Chapter Four of this paper focuses on the synthesis of polymer brushes based on the HA surface. In general, the above results analyzed from IR, XRD, SEM and DSC have proved that polymer brushes were prepared successfully on the HA surface with covalent bonds and the grafting reaction did not stimulate any structural deformation on the HA phase. From these results, it is believed that the method of grafting described in this study is of great impact on the surface modification of HA.