Spontaneous polymerization occurring

Spontaneous copolymerizations are encountered much more frequently, particularly when monomers of opposite polarity are mixed [9-10]. Early workers noticed that, upon mixing of certain electron-rich and electron-poor olefins, spontaneous polymerizations occurred without added initiator [99, 124 128]. Mixing electron-rich olefins with electron-poor olefins almost always results in brightly colored solutions. The colors are due to the CT excitation (hvCT) of the electron-donor-acceptor (EDA) complex [129], Theories for these spontaneous polymerizations mostly center around the charge-transfer complexes (CT or EDA complexes) [128]. 

Spontaneous polymerization occurs when the equilibrium concentration of the complex is high enough. Lower temperatures favor complex formation, while polymerization may require thermal or catalytic activation. Since the polymerization with and without the radical catalyst follows the same course, the comonomer complex is considered to be the polymerizable species in either case. 

The stability of the unsaturated furanuronate 159 at room temperature is limited spontaneous polymerization occurs within several days, resulting in a white solid that is insoluble in most organic solvents. The instability may be attributable to its acrylic ester structure, involved in the furanoid system. Nevertheless, other 3,4-unsaturated 3-deoxyfuranu-ronate conjugates obtained from divers mononucleotides did not prove to be unstable. 

By the late 1960 s there were a number of reports in the literature of spontaneous polymerization occuring on mixing an electron donor and an electron acceptor, one or both of which was a vinyl monomer. The mechanism which was proposed for some of these polymerizations consisted of formation of a charge transfer complex, thermal one electron transfer ("T class reaction), coupling of the radical cation and radical anion (homo-or hetero-coupling) and then anionic or cationic propatation (or both ). I was confident that we could make a contribution to the mechanism of this poly-... 

It is evident that a large difference in the rotation of monomer and polymer exists, so that the rate constants can be calculated with high precision. The results of these experiments were very reproducible, but the kinetic data were partly obscured by the fact that even after careful purification of dimethylformamide, spontaneous polymerization occurred to a small extent. 

An explosive decomposition in an ethylene oxide (EO) distillation column, similar in its results to that described in Section 7.3.2, may have been set off by polymerization of EO in a dead-end spot in the column base where rust, a polymerization catalyst, had accumulated. Such deadends should be avoided. However, it is more likely that a flange leaked the leaking gas ignited and heated an area of the column above the temperature at which spontaneous decomposition occurs. The source of ignition of the leak may have been reaction with the insulation, as described... 

The thermal polymerization of S has a long history.310 The process was first reported in 1839, though the involvement of radicals was only proved in the 1930s. Carefully purified S undergoes spontaneous polymerization at a rate of ca 0.1% per hour at 60 C and 2% per hour at 100 °C. At 180 aC, 80% conversion of monomer to polymer occurs in approximately 40 minutes. Polymer production is accompanied by the formation of S dimers and trimers which comprise ca 2% by weight of total products. The dimer fraction consists largely of cis- and trans-1,2-diphenylcyclobutanes (90 and 91) while the stereoisomeric tetrahydronaphthalenes (92 a nd 93) are the main constituents of the trinier fraction.313... 

Similar results are obtained from incineration of polymeric materials with octabromo- and pentabromodiphenyl ether (refs. 11,12). The temperature with the maximum PBDF-yield depends on the kind of polymeric matrix. All three bromo ethers 1-2 give the same isomer distribution pattern with preference for tetrabrominated dibenzofiirans. The overall yield of PBDF is lower for incineration of pentabromobiphenyl ether 2, 4 % at 700°C compared to 29 % for ether 1 at 500 °C (ref. 12). The preferred formation of tetrabrominated fiirans observed at all temperatures cannot be a result of thermodynamic control of the cyclisation reaction it is likely due to the special geometry of the furnaces. One explanation is that a spontaneous reaction occurs at approximately 400°C while the pyrolysis products are transferred to the cooler zones of the reactor details can be found elsewhere (ref. 12). 

The polymerization of ethylene in the presence of aluminum chloride is fundamentally changed by the presence of metallic aluminum (Hall and Nash, 72). The product which was obtained at a reaction temperature of 100-200° under superatmospheric pressure was a mobile fuming liquid which was shown to contain diethyl aluminum chloride, a liquid spontaneously inflammable in air. Less conjunct polymerization occurred, the lower-boiling product consisting of olefins mixed with only minor amount of paraffins. 

L.E. Wolinski, Fluorovinyl Monomers , in Vinyl and Diene Monomers , E.C. Leonard, Ed, J. Wiley, NY (1971), 1321-28 [This survey article presents circa 1971 information on all aspects of VF2. Several facets of this article are of interest the expl concn limits of the monomer with air is reported as 5.8 to 20.3%, and the fact that spontaneous polymerization of the monomer does not occur] 5) W.L. Elban, The Development of an Inert Simulant for HNS/ Teflon Explosive , NOL TR 72-255 (1972)... 

The critical conditions for runaway during polymerization, which were evaluated from the course of temperature and pressure, are shown in Fig. 7.2-3. Four different areas can be distinguished. At pressures and temperatures below the curve at the bottom, no reaction takes place. In the area above, a stable polymerization occurs. At conditions above the dashed line, decomposition can start during polymerization after an induction period. At higher temperatures and pressures a spontaneous decomposition can be observed. 

Donor-acceptor interactions are the first step in some Diels-Alder reactions7,22 between electron-poor olefins and electron-rich olefins, and also in spontaneous polymerization which can occur during cycloaddition reactions of olefins23. 

Alkenes conjugated with carbonyl groups, such as acrylates (derivatives of acrylic acid), are easily polymerized by a variety of mechanisms. Indeed, these compounds are often difficult to store because they polymerize spontaneously when traces of weak nucleophiles (even water) or radicals (even oxygen) are present. Radical polymerization occurs very easily because the intermediate carbon radical is stabilized by conjugation with the carbonyl group. 

Zwitterions are the propagating species in a number of spontaneous polymerizations that occur upon mixing electron donor and acceptor monomers. Several reviews of spontaneous polymerizations via zwitterion intermediates are available [317-323]. In this novel type of polymerization reaction there is no need to add an initiator or catalyst. Alternating copolymers have been obtained in some cases when at least one of the monomers contains a heterocycle. In these polymerizations a nucleophilic monomer (Mn) and an electrophilic monomer (Me) react to form a zwitterion [Eq. (89)]. This zwitterion is referred to as a genetic zwitterion. ... 

Ethyl glyoxylate (EtG) spontaneously polymerizes at room temperature. A distillation step on P2O5 is first necessary to break the oligomers and obtain pure EtG. A previous study on the polymerization of EtG (2) showed that the optimum conditions are to work in CH2CI2 at -20°C, with triethylamine as an initiator. A lot of transfer reactions occur in the medium leading to low molar masses and to a hydroxyl ended PEtG. 

CNC REZ BLEND OS is a modified glyoxal base cross-linking agent containing a latent catalyst, weighter, synthetic softener and lubricant. It provides a convenient low cost method for producing high quality "Wash Wear" or "Durable Press" finishes. In spite of the contained catalyst, spontaneous polymerization does not occur and shelf life is excellent. 

Styrene (and derivatives) also possesses the rare monomer quality that the neat material, without initiator, may be spontaneously polymerized by simply heating to 80-100°C for 24-48 hr. It is thought that this occurs via the initial Diels-Alder dimerization of styrene to the two diasteomers A and B [14]. The two diastereomers appear to have an extremely labile hydrogen, which is both doubly allylic and tertiary. However, only dimer A has the correct stereochemistry (an axial phenyl), which enables the excess styrene to abstract a hydrogen atom from it, producing two radical species (Eq. 23.5). 

MMT and EPON-828, the DSC curve (Fig. 17) indicates that the spontaneous clay exfoliation epoxide polymerization occurred at an onset temperature of 229 °C. On the basis of the integrated peak area, the heat of reaction for the composite was 572 J/g. DSC curves for the neat epoxy resin and the pristine [H3N(CH2)n-COOH]+-MMT are shown for comparison in Figs. 18 and 19 respectively. In the absence of a catalyst, self polymerization of the neat resin occurred at a much higher onset temperature of 384 °C but the heat of reaction (611 J/g) was comparable to that observed for the corresponding nanocomposite (572 J/g), when corrected for the presence of clay (572/0.95) or 602 J/g. 

The formation of cyclic structures during the polymerization processes had led to many interesting and useful polymers. Aqueous solution of N,N-dimethyl-3,4-dimethylenepyrrolidinium bromide were found to polymerize spontaneously at 60°C. The polymerization occurs by a 1,4-addition and the polymer product has properties very similar to that of poly(N,N-dimethyldiallylammonium chloride). High molecular weight polymers were obtained with monomer concentrations of 40-50%. Higher monomer concentrations yielded insoluble gels. 

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