甲基丙烯酸-N,N-2-甲基乙胺酯原子转移自由基聚合反应表观反应级数研究

为了研究甲基丙烯酸-N，N-2-甲基乙胺酯(DMAEMA)原子转移自由基聚合的表观反应级数，应用初级自由基的原子转移化学反应平衡、链自由基的链增长反应以及链自由基的原子转移化学反应平衡等三类基元反应构成的DMAEMA原子转移自由基聚合反应机理，通过建立聚合反应的动力学模型，研究了在DMAEMA原子转移自由基聚合反应的链引发体系中，链引发剂和催化剂的表观反应级数。结果表明，在DMAEMA原子转移自由基聚合反应的链引发体系中，链引发剂EBIB和催化剂溴化亚铜的表观反应级数均为0．8985。研究了在DMAEMA原子转移自由基聚合反应体系中，链引发剂和总的链增长自由基的浓度随单体转化率的变化关系。在聚合反应初期，总的链增长自由基的浓度随单体转化率的增加而急剧增加，当单体转化率达到40％时，总的链增长自由基的浓度近似保持为常数。链引发剂的浓度在反应初期迅速减少，表明在DMAEMA原子转移自由基聚合反应的早期，体系中存在大量的初级自由基，这些初级自由基使得大部分的链自由基在很短的时间内生成。

The Apparent Reaction Orders of the Atom Transfer Radical Polymerization of 2-(N,N-Dimethylamino)ethyl Methacrylate

In order to investigate the apparent reaction orders of the atom transfer radical polymerization (ATRP) of 2-(N,N-Dimethylamino) ethyl Methacrylate (DMAEMA), a polymerization mechanism that includes the initiation equilibrium of initiator, the propagation of growing polymer radical, and the deactivation equilibrium of growing polymer radical for the ATRP of DMAEMA was used to study the orders of polymerization reaction with respect to the components of the initiating systems in ATRP processes of DMAEMA. It was found that the apparent rate orders with respect to both initiator of ethyl 2-bromoisobutyrate (EBIB) and catalyst of cuprous bromide are 0.8985 in the ATRP of DMAEMA. The rate of polymerization can be treated as first-order for both initiator and catalyst. The variation of concentrations of initiator and total growing polymer radicals with the conversion of monomer in the ATRP of DMAEMA were also studied. The result showed that at the beginning of the polymerization, the concentration of total growing polymer radical increases very sharply, and after the conversion reaching a certain level, saying 40%, the concentration of total growing polymer radical remains nearly constant. The concentration of initiator decreases very rapidly at the beginning of the polymerization. This phenomenon means that at the early stage of the polymerization there are many number of active radicals and these radicals make most polymer chains born in a short period of reaction time.