Hydrocarbon monomers

Hydrocarbon Monomers.—The flash polymerization on mixing of isobutylene and EtAlClj was studied by Russian workers. A series of publications by a group of Italian workers describes detailed examination of the structure of homo and copolymers of several alkenes and dienes. This enabled polymerization mechanisms to be explained in terms of relative reactivities of the intermediate carbenium ions towards different monomers and their rearrangements involving hydride and methide shifts. Monomers studied were propylene, but-l-ene, isobutylene/ butadiene, isobutylene/rrans-l,3-pentadiene, isobutylene/isoprene, and propylene/but- 1-ene.  

In a study of the cationic polymerization of propylene, but 1 ene and ds-but-2-ene, Puskas et alP concluded that the kinetics could be explained by a rate-controlling initiation step rather than the 30 year old Fontana-Kidder mechanism involving slow propagation. 

Dienes frequently reduce rates and molecular weights when copolymerized with vinyl monomers and this was a feature of the isobutylene/methylene cyclobutene 

Other relevant papers on the cationic homo and copolymerization of hydrocarbon monomers include studies involving the following compounds fulvenes, isopropenylnaphthalene, halovinyl naphthalenes, cyclic dienes, anthracene, cyclopentadiene/butadiene, and 4-methylpent-l-ene.  

In the coordination polymerisation of olefins, the active site of the catalyst usually contains an alkyl group as the metal substituent forming with the metal an Mt-C active bond of the a type. The polymerisation consists in the insertion of the coordinated monomer into this bond with the regeneration of a metal-carbon bond of the same character [5], The initiation and propagation steps in the coordination polymerisation of olefins in the presence of catalysts containing an ethyl initiating group bound to the metal atom are as follows  

It is evident that each polymerisation step involves the insertion of the coordinating olefin into the active metal-carbon a bond. 

It is to be added in this connection that, like alkenes, acetylene can also undergo insertion polymerisation in the presence of some coordination catalysts, following a reaction analogous to (2) [43,44], 

In the case of catalysts for the polymerisation of conjugated dienes, the initiating substituent or the ultimate monomer unit of the growing polymer 

It is clear that each polymerisation step involves the insertion of the coordinated conjugated diene into the active metal-carbon a bond, becoming a n bond owing to this insertion, which by subsequent monomer coordination reverts to a a bond. 

---

Carbon, hydrogen and possibly oxygen Resin and derivatives Natural drying oils Cellulose derivatives Alkyd resins Epoxy resins (uncured) Phenol-formaldehyde resins Polystyrene Acrylic resins Natural and synthetic rubbers Carbon monoxide Aldehydes (particularly formaldehyde, acrolein and unsaturated aldehydes) Carboxylic acids Phenols Unsaturated hydrocarbons Monomers, e.g. from polystyrene and acrylic resins... 

Formation of block polymers is not limited to hydrocarbon monomers only. For example, living polystyrene initiates polymerization of methyl methacrylate and a block polymer of polystyrene and of polymethyl methacrylate results.34 However, methyl methacrylate represents a class of monomers which may be named a suicide monomer. Its polymerization can be initiated by carbanions or by an electron transfer process, the propagation reaction is rapid but eventually termination takes place. Presumably, the reactive carbanion interacts with the methyl group of the ester according to the following reaction... 

This reagent has been shown by Fetters et al. (19) to successfully remove water and air from various hydrocarbon monomers. In some cases, the styrenic monomers can be passed through columns of silica and activated alumina followed by degassing to obtain anionic grade monomers. 

The cured polymer samples used for physical property testing were prepared by photocuring 12 mil thick sheets of degassed and photosensitized monomer mixtures, using a mold composed of glass plates lined with polyester film and separated by a double thickness of vinyl electrical tape. A GE sunlamp was used for Illumination, and Darocure 1173 (E. Merck) was used as the photoinitiator. Hydrocarbon monomers were used as received from the manufacturers. All the vinyl group-containing compounds were stored at -5°C until use. 

At this time in the investigation, the discovery was made that incorporation of a different hydrocarbon monomer at modest levels improved Property E of these copolymers. Thus, another designed experiment was necessary to determine the optimal formulation. He decided to return to the factorial design because we wanted to reexamine the effects of SiUMA chain length in combination with Variable IV. The design is set out in Table VII. 

In 1968, a French Patent issued to the Sumitomo Chemical Company disclosed the polymerization of several vinyl monomers in C02 [84], The United States version of this patent was issued in 1970, when Fukui and coworkers demonstrated the precipitation polymerization of several hydrocarbon monomers in liquid and supercritical C02 [85], As examples of this methodology, they demonstrated the preparation of the homopolymers PVC, PS, poly(acrylonitrile) (PAN), poly(acrylic acid) (PAA), and poly(vinyl acetate) (PVAc). In addition, they prepared the random copolymers PS-co-PMMA and PVC-co-PVAc. In 1986, the BASF Corporation was issued a Canadian Patent for the preparation of polymer powders through the precipitation polymerization of monomers in carbon dioxide at superatmospheric pressures [86], Monomers which were polymerized as examples in this patent included 2-hydroxyethylacrylate and iV-vinylcarboxamides such as iV-vinyl formamide and iV-vinyl pyrrolidone. 

P, N, O, S, or C based, which favor covalent bonding and stabilize low oxidation states) due to the metals higher electronegativity and lower oxidation states [24], In recent years, late transition metal catalysts [25-29] have attracted attention not only for the polymerization of a-olefins, but more importantly for the copolymerization of hydrocarbon monomers with readily available polar monomers such as acrylates, vinyl ethers, and vinyl acetate [27 and references therein]. 

The anions originate from the attachment of an electron to whatever electron acceptors are available in the system in bulk hydrocarbon monomer this results in the formation of radical anions. Because the electron affinities of alkenes are much lower than the ionization potentials of hydrocarbon radicals, the neutralization reaction between the cations and the anions, one possible version of which is... 

We now consider the polymerizations in bulk, i.e., without a solvent, of hydrocarbon monomers by ionizing radiations in the light of the monomer complexing of cations which has been noted for polymerizations in solution. If in a solvent of low polarity this... 

The polymerizations of hydrocarbon monomers by ionizing radiations differ from those of the VE in several respects which have been set out at the end of Section 2.1 now show that the reaction patterns of the hydrocarbons and the ways in which they differ from those of the VE can be explained adequately by my theory. Unfortunately, c is not known for any of these systems, so that no rate-constants can be calculated by the established method, but another method has been devised based on DP information. 

There is sufficient information on CT complexes of this kind in Foster s book [6] for the Kus to be estimated. By extrapolating from 1,3,5-trinitrobenzene and 1,4-dinitrobenzene to PhN02 for any one electron donor (mesitylene or hexamethyl benzene), and from CC14 to solvents of D > ca 10, we find that at least for the three hydrocarbon monomers it is very unlikely that Kus > 10 2 1-mol 1. Therefore, since [Sv] = ca 10 mol-1 1 ([molar vol]"1), we find for m = 1 mold"1, that [MSv] <0.1 mold"1, which means that for these monomers >90% of the monomer is not bound in a CT complex, and the first objection is therefore not relevant. For the monomers containing both 7t- and n-donor groups, i.e., the VE, the Kus may well be greater, and therefore the formation of CT complexes may be important for these. 

The Kus can be estimated as follows an extrapolation of the Kus for the CT complex formed by any one donog such as mesitylene or hexamethylbenzene, with 1,3,5-trinitrobenzene and 1,4-dinitrobenzene to PhN02, and an extrapolation from solvent CC14 to one of DC > ca. 10 (Foster, 1969) shows that for our system Kus is very unlikely to be greater than 0.01 hmol"1. Therefore, with m = 1 mold"1, and [Sv] = 10 mold"1, [MSv] < 0.1 mold 1. This means that for styrene and other 7t-donors effectively all the monomer is free. For n-donor monomers such as the VE, however, the fraction of uncomplexed monomer may be somewhat smaller. Therefore it appears that the formation of CT complexes probably did not affect significantly at least the results for the three hydrocarbon monomers. 

Table 2 Cationic systems Aromatic hydrocarbon monomers ...

Strictly, there is no direct evidence concerning the presence of ions for any aliphatic hydrocarbon monomers. The spectroscopic studies which are of such great diagnostic value for aromatic systems are at present useless for those involving aliphatic monomers and therefore such information as we have for these (Table 3) consists of measurements of electrical conductivity and other, more circumstantial, evidence. It is not claimed that the evidence assembled in these Tables is complete and as far as Table 3, especially, is concerned, its content depends obviously on what one considers to be satisfactory evidence for the participation of ions. 

Anionic polymerisation of hydrocarbon monomers is initiated by lithium butyl to produce a living polymer the association number of which in solution is required to elucidate the kinetics. When the living polymer (for example polystyryl lithium) is terminated, the polystyrene can be isolated and a solution then made to determine its molecular weight, M. If the living polymer is associated in solution, the ratio of its... 

An alternative approach to the use of partially fluorinated systems to reduce the cost of fluorinated PEMs has been developed by DeSimone et al. a perfluo-rinated vinyl ether is copolymerized with a hydrocarbon monomer (styrene), sulfonated, and then subsequently fluorinated to replace existing C-H bonds with C-E bonds (Eigure 3.18). Thus yields the perfluorinated, cross-linked sul-fonyl fluoride membrane that can then be hydrolyzed to give the PEM (7). Because the membranes are cross-linked, considerably higher acid contents (up to 1.82 meq/g) are possible for these materials in comparison to Nafion, leading also to higher proton conductivity values. 

An alternative method to make PAEs is the acyclic diyne metathesis (ADIMET) shown in Scheme 2. It is the reaction of a dipropynylarene with Mo(CO)6 and 4-chlorophenol or a similarly acidic phenol. The reaction is performed at elevated temperatures (130-150 °C) and works well for almost any hydrocarbon monomer. The reaction mixture probably forms a Schrock-type molybdenum carbyne intermediate as the active catalyst. Table 5 shows PAEs that have been prepared utilizing ADIMET with these in situ catalysts . Functional groups (with the exception of double bonds) are not well tolerated, but dialkyl PPEs are obtained with a high degree of polymerization. The progress in this field has been documented in several reviews (Table 1, entries 2-4). Recently, a second generation of ADIMET catalyst has been developed that allows... 

Particular attention has been given to 1,3-pentadiene, the simplest hydrocarbon monomer capable of giving chiral polymers. Natta, Porri, and co-workers... 

Genetron Fluorinated hydrocarbon monomers and polymers Allied Chemical... 

Table 7. Fitted Rate Coefficients for the Plasma Polymerization of Unsaturated Hydrocarbon Monomers...

Co-polymerization of hydrocarbon monomers with polar monomers... 

---