反应型受阻胺-4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP)熔融本体光聚合反应动力学研究

合成了反应型受阻胺4-丙烯酰胺基-2,2,6,6-四甲基哌啶(AATP),用FTIR、¹H-NMR和元素分析对其结构和组成进行了综合表征.以AATP为聚合单体,利用光-DSC技术研究了AATP熔融本体光聚合反应动力学.结果表明:AATP光聚合的诱导时间随引发剂浓度和辐照光强增加而缩短,光聚合速率随温度的升高而减小;在聚合初期,AATP光聚合速率分别与引发剂浓度和辐照光强的平方根呈较好的线性增长关系.并用稳态和非稳态相结合的光-DSC方法测定了AATP光聚合过程的动力学参数:链增长速率常数k_p=2.22-7.96×10²L/mol·s、链终止速率常数k_t=0.08-2.67×10⁴L/mol·s、表观活化能为E_p-E_t/2=-7.70-13.36kJ/mol、指前因子A_p/A_t^0.5=0.076-0.333(L/mol·s)0.5,k_p和k_t在聚合初期均随单体转化率的提高而增大,但kt增加的幅度远大于k_p.

Reaction Kinetics of Photoinduced Bulk Polymerization of 4-Acrylamido-2,2,6,6-Tetramethyl- Piperidine in Melting State

4-acrylamido-2,2,6,6-tetramethyl-piperidine(AATP),a water soluble r-HALS,is synthesized and the structure and composition of AATP is characterized by FT-IR,~1H-NMR and elemental analysis.The reaction kinetics of photoinduced bulk polymerization of AATP in melting state is studied by using photo-DSC (DPC) technique.The results show that the conversion and the rate of AATP photopolymerization are obviously affected by the reaction condition such as temperature,incident light intensity and concentration of photoinitiator etc.Darocur 1173 is the available initiator and the optimum mass fraction of Darocur 1173 is 0.5—1.0 %.The rate of AATP photopolymerization is proportional to the square root of photoinitiator concentration c~(0.5)_(PI) and incident light intensity I~(0.5)_0 respectively under given condition.The kinetic parameters of photoinduced bulk polymerization for AATP were measured at the steady and non-steady state.The rate constants for termination k_t is much larger than that for propagation k_p(k_p/k_t=3.43—33.57).k_t and k_t is increased with the conversion increasing in the reaction system.k_p and k_t is 2.22—7.96×10~2 and 0.08—2.67×10~4(L/mol·s) corresponding to a conversion from 4.00% to 15.68%,respectively.These values are within the range of corresponding parameters typical for a free radical polymerization.The induction period of the reaction system is decreased with the increment of photoinitiator concentration and incident light intensity respectively.Because of apparent activation energy of the reaction system is negative E_p-E_t/2 is from -7.70 to -13.36 kJ/mol] and A_p/A_t~(0.5) is from 0.076 to 0.333(L/mol·s)~(0.5),the rate of AATP photopolymerization is decreased with increment of the temperature from 110 ℃ to 150 ℃ and the irradiating time of that is prolonged.