Study On Reaction Kinetics Of Photo-induced Polymerization Of Reactive Hindered Piperidinol Derivatives (r-HAPD)

In this thesis, the kinetic performance of photo-induced polymerization of Reactive Hindered Piperidinol Derivatives (r-HAPD) was studied, and the photo-induced bulk and solution polymerization of r-HAPD has been investigated by using differential photo-calorimeter (DPC) and ESR technique respectively. From the view of utility, we have also studied the copolymerization performance of r-HAPD with methacrylate(M A).The complex kinetic behaviors of r-HAPD in the polymerization were opened out by probing into the mechanism of controlled free radical photopolymerization of r-HAPD. We first developed a new route to realize the controlled /"living" free radical photopolymerization of acrylate monomer.The following is main conclusions of our work:1. Four r-HAPD: 4-methacryloyl-l,2,2,6,6-pentamethyl-piperidinyl(MPMP), 4-acryl oyl-1,2,2,6,6-pentamethyl-piperidinyl (APMP), 4-methacryloyl-2,2,6,6-tetrame-thyl-piperidinyl (MTMP) and 4-acryloyl-2,2,6,6-tetramethyl-piperidinyl (ATMP) were synthesized by direct transesterification between hindered piperidinol and a, p-unsaturated ester. Two r-TEMPO: 4-methacryloyloxy-2,2,6,6-tetramethyl-pipe-ridinyl-1-oxy (MMA-TEMPO) and 4-acryloyloxy-2,2,6,6-tetramethyl-piperidinyl-l-oxy(MA-TEMPO) were synthesized and characterized by FTIR, 'H-NMR, ESR, DTA and elemental analysis. The results prove the structure of r-TEMPO.2. By using DPC technique, the kinetics of photo-induced bulk polymerization ofr-HAPD have been systematically studied in melting state under different reaction conditions. The results are summarized as follows:1) The rate of r-HAPD photopolymerization is greatly influenced by the reaction conditions such as the type and concentration of photoinitiator, temperature, atmosphere as well as light intensity, and is directly proportional to the square rootof photoinitiator concentration and incident light intensity , which is inaccordance with the theoretical expectation. The inhibition of O₂ is obviously influence on the polymerization of r-HAPD.2) The kinetic parameters ( kp and k_t) of r-HAPD photopolymerization have beendetermined by DPC technique at the steady state and the non-steady state. Using Irgacure651 as a photoinitiator, for ATMP, kp kept invariable but kt decreasedfast with the increase of MTMP conversion (kp= 0.03⁰.65xl03 L/mol-s-1, k,= 0.006-0.94 x 105 L/mol-s^-1), for ATMP, kp increased with ATMP conversion in thelow conversion stage (< 18 %), and then decreased slowly, kt increased in thelow conversion stage (< 8 %) and then decreased rapidly with the increase of ATMP conversion, but kt was much larger than kp(kp = 0.17².40xl03 L/mol-s-1,k = 0.17-9.35 xl05 L/mol-s-1). kp and kt of MTMP were less than those of ATMPshows that ATMP have the excellent reactivity.3) The apparent activation energy was calculated and apparent pre-exponential factor of r-HAPD photopolymerization in the low conversion in accordance with Arrhenius equation. The negative value of apparent activation energy (such as Conv.% = 3, the apparent activation energy of ATMP and MTMP was -7.29 kJ/mol and -8.49 kJ/mol respectively) shows that high temperature is disadvantaged to the polymerization of r-HAPD, and the little value of apparent pre-exponential factor shows (such as Conv.% = 3, of ATMP and MTMPis 0.125 and 0.073 respectively) that the pre-exponential factor of kt is muchlarger than that of kp .3. MA/ATMP and MA/APMP copolymers were prepared by the photo-induced solution copolymerization of MA (M₁) with r-HAPD (M2) in toluene. The reactivity ratios for these monomers were measured by running a series of reactions at various initial monomer ratios, and compositions of the copolymers determined by !H-NMR. The reactivity ratios of MA/ATMP and MA/APMP were 0.51 < r₁ < 0.56, 1.03 < r2< 1.41 and 0.82 < r₁ < 0.88, 0.47 < r2< 0.55 respectively from Mayo-Lewis method. The results from Extended Kelen-Tudos method were r₁ = 0.53, r2= 1.31 (MA/ ATMP) and r₁ = 0.82, r2 =...