聚合物合成
聚合物是一类由小重复化学单元组成的物质。聚合物中的合成砌块或重复单元称为单体。聚合或聚合物合成是一种化学反应，单体通过共价键结合在一起形成聚合物结构。聚合物链的长度用链中重复单元数量表示，称为聚合度（DP）。聚合物的分子量是重复单元分子量和DP的乘积。聚合物的固有基本特性主要取决于分子量、结构（直链或支链）和DP。
根据涉及化学反应的类型，聚合分为两类，分别称为缩合聚合和加成聚合。在缩合聚合或逐步增长聚合中，两种不同的双官能或三官能单体之间发生缩合反应，产生聚合物，由此反应中消除了小分子（通常是水）。在加成聚合或链增长聚合中，聚合物的增长是通过在聚合物链末端的活性位点添加单体，并在每次增长步骤完成后再生活性位点来实现的。需要引发剂产生具有反应中心的引发剂物质。反应中心可以是自由基、阳离子、阴离子或有机金属络合物。
聚合物的特性高度依赖于单体类型和合成的聚合方法。活性自由基聚合，也称为受控自由基聚合（CRP），可以更好地控制聚合物分子量、分子量分布、官能度和组成。而且还可以与多种乙烯基单体结合，构建具有不同性质的聚合物，满足不同用途。
目前CRP技术主要有三种：
- 原子转移自由基聚合（ATRP）
- 可逆加成/断裂链转移（RAFT）聚合
- 一氧化氮介导的聚合（NMP）
ATRP非常适合表面改性应用，这类应用依赖于定制的亲水性，粘合特性或纳米粒子功能化。由RAFT和ATRP衍生的聚合物都可以在聚合后改性，在生物医学领域广泛用于药物传递和组织工程应用。生物医学领域应用的嵌段共聚物通常由RAFT或ATRP开发。由NMP开发的嵌段共聚物对于颜料分散、存储设备和复合材料制造至关重要。
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