Vinyl Monomer Based Polyperoxides as Potential Initiators for Radical Polymerization: An Exploratory Investigation with Poly(.alpha.-methylstyrene peroxide (original) (raw)
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New azo-peroxidic initiators in the radical polymerization of styrene and methyl methacrylate
European Polymer Journal, 2009
Two new azo-perester compounds, di-tert-butyl-6,6 0-azobis-(6-cyanoperoxyheptanoate) (6,6-di-tBu) and di-tert-amyl-6,6 0-azobis-(6-cyanoperoxyheptanoate) (6,6-di-tAm), synthesized on the basis of 6,6 0-azobis-(6-cyanoheptanoic acid) (ACHpA), were investigated for their use in the radical polymerization of styrene (S) and methyl methacrylate (MMA). Their characteristics are given, including chemical (IR spectra), thermal (DSC) and kinetic, i.e., thermal decomposition studied by volumetric and gas chromatographic methods. The rate constants and activation energies of the decomposition of both the azo and perester bonds were determined. The new azo-peresters were utilized to initiate the radical solution polymerizations of S and MMA at 60°C. The kinetic parameters of the processes, i.e., polymerization rate and overall rate constant, were determined. Subsequently, the polymerization products were characterized by IR and DSC. It was found that the perester groups were present in the obtained polymers, and hence, the polymers are ''active" for further polymerization.
Journal of Polymers and the Environment
Autoxidation of unsaturated fatty acids gives fatty acid macroperoxide initiators containing two functionalities which can lead to free radical and condensation polymerizations in a single pot. The oleic acid macroperoxide initiator obtained by ecofriendly autoxidation (Pole4m) was used in both the free radical polymerization of styrene and the condensation polymerization with amine-terminated polyethylene glycol (PEGNH2) to obtain triblock branched graft copolymers. The narrow molar masses of the poly oleic acid-g-styrene (PoleS) and poly oleic acid-g-styrene-g-PEG (PoSG) graft copolymers were successfully obtained. The inclusion of oleic acid decreased the glass transition temperature of the polystyrene segment because of the plasticizing effect of oleic acid. In addition, a mechanical property of the copolymer was improved when compared with the pure PS. Structural characterization, morphology of the fracture surface, micelle formation, thermal analysis and molar masses of the obtained products were also evaluated.
Recent Advances in the Study of Multifunctional Initiators in Free Radical Polymerizations
Macromolecular Reaction Engineering, 2007
When reviewing the state of research completed on multifunctional initiators, there appears to be a lack of comprehensive studies following a systematic approach to understanding their behaviour in free radical polymerizations. Apart from a few exceptions, most studies have focused entirely on the free radical polymerization of styrene and neglected to examine the behaviour of the initiator in question with various other monomers. Additionally, some of the previous papers employ a less than ideal method of proving the rate benefits of
Gas-free initiators for high-temperature free-radical polymerization
Journal of Polymer Science Part A-polymer Chemistry, 2000
Quaternary ammonium persulfates as free-radical initiators for high-temperature polymerization are synthesized and their shelf-life stability investigated. These initiators do not have gaseous byproducts and are therefore ideal for frontal polymerization, a process in which polymeric materials are produced via a thermal front that propagates through the unreacted monomer/initiator solution. Quaternary ammonium persulfate initiators offer additional qualities such as high solubility in organic media and low volatility, which are desirable for frontal polymerization. The initiators are synthesized using two procedures, and the initiating efficacy of the respective products is compared to a peroxide initiator in the frontal polymerization of 1,6-hexanediol diacrylate. Of all the quartenary ammonium persulfates synthesized, tricaprylmethylammonium (Aliquat) persulfate (APSO) is the best initiator for frontal polymerization because it is soluble in organic media, is very reactive, and does not produce volatile byproducts under decomposition. A study of the decomposition kinetics of APSO is performed, and frontal polymerization is proposed as a quicker analytical technique to assay the purity.
Amine Peroxide Initiated Polymerization Reactions: Effect on Molecular Weight
Limitations often encountered in the polymer molecular weight MW and molecular weight distribution MWD has promoted research into unconvectional free radical initiators. A traditional free radical macromolecular initiator has recently been investigated for peroxide modification of the surface of disperse fillers and pigments with the objective to enabling their participation in the elementary reactions of polymerization: initiation, chain propagation and termination, resulting in the formation of an interfacial polymer layer with macromolecules grafted to the surface. Polymerization kinetics of vinyl monomers initiated by this amine-containing initiator under homophase and heterophase conditions has been examined with respect to the effect on the resulting polymer MW by means of dilatometric and viscosimetric measurements. Poly(methyl methacrylate) formed under corresponding conditions is characterized by about 2-3 times higher values of MW as compared to polystyrene. In particular, significant deceleration of the termination reactions upon interaction of growing macroradicals due to diffusion complications has been observed. High polymerization rate with the production of high-MW products resulting from the application of high-MW initiator, as compared to convectional low-MW peroxides has been attributed to the polymerization – polyrecombination mechanism of the formation of macromolecule
Influence of thermal initiation on the radical polymerization of unsaturated monomers
Journal of Polymer Science Part A: Polymer Chemistry, 1989
The effect of thermal initiation of the radical polymerization of unsaturated monomem has been analyzed by considering a kinetic scheme that includes thermal: and catalyst-induced formation of free radicals, propagation, and termination reactions. Expressions relating the different rate constants with the instantaneous monomer concentration are derived and they indicate the great influence of thermal initiation on the kinetic results. Application to a real case suggests that evaluation of k , and k , / k~/ 2 from experimental results using the method of dead-end polymerization may lead to erroneous values of these constants.
Bubble-Free Initiators for High Temperature Free-Radical Polymerization
Quaternary ammonium persulfates as free-radical initiators for high-temperature polymerization are synthesized and their shelf-life stability investigated. These initiators do not have gaseous byproducts and are therefore ideal for frontal polymerization, a process in which polymeric materials are produced via a thermal front that propagates through the unreacted monomer/initiator solution. Quaternary ammonium persulfate initiators offer additional qualities such as high solubility in organic media and low volatility, which are desirable for frontal polymerization. The initiators are synthesized using two procedures, and the initiating efficacy of the respective products is compared to a peroxide initiator in the frontal polymerization of 1,6-hexanediol diacrylate. Of all the quartenary ammonium persulfates synthesized, tricaprylmethylammonium (Aliquat) persulfate (APSO) is the best initiator for frontal polymerization because it is soluble in organic media, is very reactive, and does not produce volatile byproducts under decomposition. A study of the decomposition kinetics of APSO is performed, and frontal polymerization is proposed as a quicker analytical technique to assay the purity.