聚甲基丙烯酸-N,N-二甲氨基乙酯的紫外光引发溶液聚合及性能研究

采用紫外光引发溶液聚合得到了甲基丙烯酸-N，N-二甲氨基乙酯(DMAEMA)聚合物，研究了聚合过程中引发剂安息香乙醚(BE)用量、单体浓度、光引发时间对聚合速率、产率及分子量的影响，实验确定了制备线型聚甲基丙烯酸-N，N-二甲氨基乙酯聚合物(PDMAEMA)的工艺及方法。采用膨胀计法研究了聚合反应，结果表明：DMAEMA单体可能同时参与了光引发过程。通过对PDMAEMA水溶液性能研究发现，PDMAEMA水溶液具有明显的温度及pH敏感性。

Solution Polymerization of Poly(N,N-Dimethylaminoethyl Methacrylate) Photo-Initiated by Ultraviolet(UV) and its Properties

It is well known that poly(N,N dimethylaminoethyl methacrylate) or PDMAEMA has wide applications as a biomedical material. Ref.2 prepared PDMAEMA hydrogels by UV irradiation and studied its swelling kinetics and stimuli responsiveness. We prepared linear PDMAEMA--solution polymerization of PDMAEMA photo initiated by UV--and studied its polymeric kinetics and stimuli responsiveness. In specific applications, sometimes PDMAEMA hydrogels are more useful or convenient but another time linear PDMAEMA is more useful or convenient. Section 1 reviews briefly our experimental method, procedure and equipment. Section 2 gives in much detail the experimental results and discussion. Subsection 2.1 discusses the effect of pH value. Fig.1 shows that when pH value is in the range of 1.5~2.0, both the intrinsic viscosity and product yield are improved heavily. Subsection 2.1 discusses why pH value should be within the range of 1.5~2.0. It is probably because that under the acidic condition, the N atom of N,N dimethylaminoethyl methacrylate (DMAEMA) is easily attracted to proton to form organic salt and then make the electronic cloud of double bond shift and polarize to become conducive to easy excitation of radicals and easy propagation of chains. Subsection 2.2 discusses the effect of amount of initiator. Fig.4 shows that when amount of initiator is approximately 0.02 mol/L, product yield is highest. Subsection 2.3 discusses the effect of time of exposure to UV radiation. Fig.5 shows that when the time of exposure is approximately 30 min, both the intrinsic viscosity and product yield are highest. Subsection 2.4 discusses the effect of monomer concentration, Figs. 6,7 and 8 show experimental results of monomer concentration. Fig.7 shows that test points(in Fig.7, ln R p is ordinate, and ln is abscissa, where R p is polymerizing rate and is monomer concentration) are approximately on a straight line with a slope of 1.91. The experimentally found relationship between polymerizing rate and monomer concentration suggests that the photo initiated system may consist of both DMAEMA monomer and benzoin ethylether(BE) initiator because DMAEMA is indeed a photosensitive organic compound. Subsection 2.5 discusses sensitivity. Figs.9 and 10 show that PDMAEMA aqueous solution exhibits a combined pH and temperature sensitivity.