19 research outputs found
A novel (main chain) (side chain) polymeric peroxide: Synthesis and initiating characteristics of poly(alpha-(tert-butylperoxymethyl)styrene peroxide)
A novel (main chain)-(side chain) vinyl polyperoxide, poly(alpha-(tert-butylperoxymethyl)styrene peroxide) (MCSCPP), an alternating copolymer of alpha-(tert-butylperoxymethyl)styrene (TPMS) and oxygen, has been synthesized by the oxidative polymerization of TPMS. The MCSCPP was characterized by H-1 NMR, C-13 NMR, IR, DSC, EI-MS, and GC-MS studies. The overall activation energy (E(a)) for the degradation of MCSCPP was found to be 27 kcal/mol. Formaldehyde and alpha-(tert-butylperoxy)acetophenone (TPAP) were identified as the primary degradation products of MCSCPP; TPAP was found to undergo further degradation. The side chain peroxy groups were found to be thermally more stable than those in the main chain. Polymerization of styrene in the presence of MCSCPP as initiator, at 80 degrees C, follows classical kinetics. The presence of peroxy segments in the polystyrene chain was confirmed by both H-1 NMR and thermal decomposition studies. Interestingly, unlike other vinyl polyperoxides, the MCSCPP initiator shows an increase in molecular weight with conversion
Synthesis of epoxy-terminated polymers by radical polymerization using α-(t-butylperoxymethyl)styrene as chain transfer agent
Epoxy-terminated polystyrene has been synthesized by radical polymerization using α-(t-butylperoxymethyl) styrene (TPMS) as the chain transfer agent. The chain transfer constants were found to be 0.66 and 0.80 at 60 and 70°C, respectively. The presence of epoxy end groups was confirmed by functional group modification of epoxide to aldehyde by treatment with BF3.Et2O. Thermal stability of TPMS was followed by differential scanning calorimetry and iodimetry. Thermal decomposition of TPMS in toluene follows first order kinetics with an activation energy of 23 kcal/mol
Kinetics of Poly(Styrene Peroxide) Initiated Polymerization of Methyl Methacrylate and Styrene
Poly(styrene peroxide) (PSP), an alternating copolymer of oxygen and styrene, has been used as an initiator for the radical polymerizations of methyl methacrylate and styrene. Thermal decomposition of PSP follows first order kinetics with an activation energy of 160.0 kJ/mol. Polymerizations of MMA and styrene (60–90 °C) follow the usual kinetics. The efficiency of the initiator, PSP, was found to be low (0.006–0.014), attributed to the competing unimolecular decomposition of macroalkoxy radicals and primary radical initiation. The presence of peroxy segments in the backbone of PMMA and polystyrene (PS) was confirmed by and DSC studies
Kinetics of poly(styrene peroxide) initiated polymerization of methyl methacrylate and styrene
Poly(styrene peroxide) (PSP), an alternating copolymer of oxygen and styrene, has been used as an initiator for the radical polymerizations of methyl methacrylate and styrene. Thermal decomposition of PSP follows first order kinetics with an activation energy of 160.0 kJ/mol. Polymerizations of MMA and styrene (60–90°C) follow the usual kinetics. The efficiency of the initiator, PSP, was found to be low (0.006–0.014), attributed to the competing unimolecular decomposition of macroalkoxy radicals and primary radical initiation. The presence of peroxy segments in the backbone of PMMA and polystyrene (PS) was confirmed by 1H NMR and DSC studies
Synthesis and characterization of tetrapolymers of styrene, methyl methacrylate, alpha-methylstyrene, and oxygen
This paper presents the first report on a terpolyperoxide (TPPE) synthesized by the oxidative terpolymerization of styrene, methyl methacrylate, and a-methylstyrene. TPPEs of different compositions were synthesized by varying the vinyl monomers feed, and they were then characterized by spectroscopic and thermal studies. The conventional terpolymer equation has been used to predict the composition of TPPEs. The H-1 NMR chemical shift values of TPPEs were found to vary with the composition. The shape of the backbone methylene protons (4.00-4.50 ppm) was found to be sensitive to the sequence distribution of vinyl monomers in the polymer chain. Formaldehyde, benzaldehyde, acetophenone, and methyl pyruvate were identified as the primary degradation products. The overall thermal stability and the average enthalpy of degradation (Delta H-d), as obtained by thermogravimetric analysis and differential scanning calorimetry, respectively, do not vary much with the composition of TPPEs
Poly(styrene disulfide) and poly(styrene tetrasulfide) as chain transfer agents in the radical polymerization of styrene
This is a first report on the chain transfer behaviour of polysulfide polymers, namely poly(styrene disulfide) (PSD) and poly(styrene tetrasulfide) (PST), in the radical polymerization of styrene. It was observed that while PSD acts as a conventional chain transfer agent, PST acts as a retardant. Comparison of the chain transfer constants of PSD and PST with that of the corresponding simple sulfides indicates that polysulfide polymers are better chain transfer agents
Vinyl Monomer Based Polyperoxides as Potential Initiators for Radical Polymerization: An Exploratory Investigation with Poly(.alpha.-methylstyrene peroxide)
We describe the use of poly(alpha-methylstyrene peroxide) (P alpha MSP), an alternating copolymer of alpha-methylstyrene and oxygen, as initiator for the radical polymerization of vinyl monomers. Thermal decomposition of P alpha MSP in 1,4-dioxane follows first-order kinetics with an activation energy (E(a)) of 34.6 kcal/mol. Polymerization of methyl methacrylate (MMA) and styrene using P alpha MSP as an initiator was carried out in the temperature range 60-90 degrees C. The kinetic order with respect to the initiator and the monomer was close to 0.5 and 1.0, respectively, for both monomers. The E(a) for the polymerization was 20.6 and 22.9 kcal/mol for MMA and styrene, respectively. The efficiency of P alpha MSP was found to be in the range 0.02-0.04. The low efficiency of P alpha MSP was explained in terms of the unimolecular decomposition of the alkoxy radicals which competes with primary radical initiation. The presence of peroxy segments in the main chain of PMMA and polystyrene was confirmed from spectroscopic and DSC studies. R(i)'/2I values for P alpha MSP compared to that of BPO at 80 degrees C indicate that P alpha MSP can be used as an effective high-temperature initiator