Polymers from other vinyl monomers

Allyl alcohol, CH2=CH—CH2OH (2-propen-l-ol) [107-18-6] is the simplest unsaturated alcohol. One hydrogen atom can easily be abstracted from the aHyhc methylene (—CH2—) to form a radical. Since the radical is stabilized by resonance with the C=C double bond, it is very difficult to get high molecular weight polymers by radical polymerization. In spite of the fact that aHyl alcohol has been produced commercially for some years (1), it has not found use as a monomer in large volumes as have other vinyl monomers. 

In addition to the polymer, copolymers of vinyl chloride with other vinyl monomers are important commercial plastics. Copolymers with vinyl acetate, which is produced from acetylene and acetic acid, are widely used in sheeting, surface coating, and filaments, being less brittle and more readily soluble in organic solvents than is pure polyvinyl chloride. Copolymers with acrylonitrile are also of importance for the production of... 

Copolymerization. The importance of VDC as a monomer results from its ability to copolymerize with other vinyl monomers. Bulk copolymenzations yielding high VDC-content copolymers are normally heterogeneous. During copolymerization. one monomer may add to the copolymer more rapidly than the other. Batch reactions carried to completion usually yield polymers of broad composition distribution. More often than not, this is an undesirable result,... 

The chain reaction process can be used as a diagnostic aid to determine whether free radicals are generated from a drug when irradiated. Acrylamide is an acrylic monomer, which is widely used in gel electrophoresis, as a polymer formed in situ by peroxide or UV-initiated polymerization. This monomer is a water soluble solid, more easily handled than most other vinyl monomers, and the progress of its polymerization can be readily followed by measuring its contraction in volume utilizing dilatometry, or its increase in viscosity in a viscometer. Details of this experimental technique can be found in Moore and Burt (18). 

The melt condensation of acid and hydroxyl functional group normally requires exact stoichiometry, elevated temperature, and a long reaction cycle. Such a route would not be possible to utilize to produce block polymers from lactones and other vinyl monomers. However, a rather facile route leading to polyester formation can be realized by the ring-opening polymerization of lactones as seen from the scheme ... 

The initiation processes used have included various forms of radiation as well as chemical initiators. In connection with chemical initiators, it is interesting to note that among these are water-soluble amidine salts derived from such oil-soluble initiators as 2,2 -azobisisobutyronitriIe. These water-soluble initiators tend to produce polymer latices in the presence of appropriate surfactants in the way more conventional water-soluble initiators do in the case of other vinyl monomer types. 

Preparation of Block Copolymers from Macroinitiators. In an early paper, Ceresa reported polymerization of methyl methacrylate in the presence of oxygen, and then swelling the polymer with styrene. On heating, the polymeric peroxide decomposed initiating styrene polymerization thus forming a block copolymer(89). Even earlier, macroperoxides, useful in the preparation of block copolymers, were prepared by initiating the polymerization of butadiene with m-diisopropyl benzene dihydroperoxide in an emulsion. On further heating in the presence of styrene and Fell salts, a block copolymer was formed l Recently in independent work, polypropylene hydroperoxide was prepared by ozonolysis, and with triethylenetetra-amine as an activator was used to initiate block addition of styrene(91) and other vinyl monomers(92,93). ... 

Addition polymers are of great importance and are obtained from olefin monomers by sequential covalent addition, as discussed in Chapter 1. It was observed in Chapter 2 that many vegetable oils may be heated with other vinyl monomers to modify their surface coating properties. The modification of triglyceride oils by the copolymerisation of drying and semi-drying oils with vinyl monomers such as styrene, a-methylstyrene or cyclopenta-diene, is one of the oldest methods used in vegetable oil-based chemistry. The products obtained by this technique possess improved film properties and styrene has been found to be the most important monomer for this purpose. 

Natta et al. (1960d) reported on isotactic polymer from 2-vinyl pyridine, Guyot and Quang Tho (1963) on syndiotactic polymer from vinyl chloride, and Butler et al. (1960) on isotactic polymers from iST,iSr-dialkylacrylamides. Other examples may be found in the literature, but, detailed studies have not been reported, which has also been the case with the above-named monomers. 

Both polymers were formed from their vinyl monomers. Pendant benzoin groups can be introduced into the polymers by other techniques. One can start, for instance, with a copolymer of styrene and maleic anhydride and form ester groups ... 

As can be seen in Table 1, the most common acrylic ester polymers have low Tg values and, therefore, soften films in which they are copolymerized with other vinylic monomers. This effect results in an internal plasticization of the pol5mier. That is, the plasticization effect from acrylic esters, unlike plasticizer additives which are not covalently bound, will not be removed via volatilization or extraction. 

Copolymerization. The importance of VDC as a monomer results from its ability to copolymerize with other vinyl monomers. Its Q value equals 0.22 and its e valne eqnals 0.36. It most easily copolymerizes with acrylates, but it also reacts, more slowly, with other monomers, eg, st5Tene, that form highly resonance-stabilized radicals. Reactivity ratios (ri and T2) with various monomers are listed in Table 2. Many other copolymers have been prepared from monomers for which the reactivity ratios are not known. The commercially important copolymers include those with vinyl chloride (VC), acrylonitrile (AN), or various alkyl acrylates, but many commercial polymers contain three or more components, of which VDC is the principal one. Usually one component is introduced to improve the processi-bility or solubility of the polymer the others are added to modify specific use properties. Most of these compositions have been described in the patent literature, and a list of various combinations has been compiled (41). A typical terpolymer might contain 90 wt% VDC, with the remainder made up of AN and an acrylate or methacrylate monomer. 

Because random insertion of styrene units disrupts the TT-conjugation along the polymer chain, the conductivity of the copolymer decreases with increasing concentration of styrene units. For example, the polymer prepared from a 1 1 molar mixture of both monomers in nitrobenzene at 5 C for 6 hours under nitrogen contains 30 mole% styrene units and has a four-point probe pellet conductivity of 0.02 S cm the conductivity of poly(3-MT) prepared under the same conditions is 40 S cm . Other vinyl monomers... 

Vinylidene fluoride (VF2) as well as vinyl fluoride (VF) resemble more ethylene than other vinyl monomers in regard to the properties and can also be polymerized in a manner analogous to that of ethylene. The first successful polymerization of vinylidene fluoride was reported by Du Pont in 1948 [517]. Poly(vinylidene fluoride) (PVF2 or PVDF) is commercially available from various companies (Kureha Chemical Co., Pennalt Chemicals Corp., Solvay Co., Siiddeutsche Kalkstickstoff-Werke AG now Degussa, Diamond Shamrock, Du Pont) since 1965 under the trade names KF, Kynar, Foraflon, Vidar, and Dalvor, respectively. VF2 can be polymerized by free-radical initiators to give high-molar-mass, crystalline polymers. 

N-alkyl-3-azetidinols, obtained from epidilorohydrin and a primary amine, have been polymerized to low-molecular-weight hydroxy-substituted polyamines. Transesterification of an azetidinol with methyl acrylate or methacrylate leads to the corresponding azetidinyl esters which can be polymerized or copolymetized with other vinyl monomers to produce reactive, cross-linkable polymers (Scheme 18). 

All attempts to copolymerize 1 with other vinyl monomers were unsuccessful until Salamone and coworkers obtained a 1,2-addition copolymer 4 of 1 (R = H] and 4-vinylbenzenesulfonate, 20, obtained by spontaneous polymerization oi the two monomers as a melt or in concentrated aqueous solution [61]. Vinyl-type copolymers of 1 and 20, and 1 and 21 were also obtained by initiation with radicals (e.g. from ACVA), light or y-radiation. These experiments are summarized in Table 6.3.1. Copolymerization of 1 (R = H) with AMPS 21 is complicated when carried out as a spontaneous (i.e. absence of an initiator) process in water, methanol, or iV,iV-dimethylformamide (DMF). Two homopolymers derived from 1 (R = H), the 1,2-addition polymer, 2 (R = H), and the polyionene, 7. are obtained along with poly AMPS. Similar attempts to form copolymer from 1 (R = H) and vinylsulfonate have been unsuccessful. In fact, the latter monomei resisted all conditions of polymerization and 1 (R = H) formed the ionene 7 from a melt or in dilute aqueous solution (< 1.0 m) and yielded 2(R = H) in concentrated aqueous solution. Table 6.3.1. Recall that this behavior duplicates that reported for 1 (R = H) by Ringsdorf and others. Ringsdorf attributed the change in structure of homopolymer to micellization of 1 (R = H) in concentrated aqueous solution. 

All polymers presented in this section have a common molecular structure, which induces a semicrystalline morphology. They are different from other vinyl polymers whose mechanical properties are similar to those of their amorphous state. The partial crystallinity of these halogenated polymers has to be considered with their glass transition temperature, which is lower than the ambient temperature for most of them. Moreover, they have at least one halogen atom in each monomer unit and hence they are flame-resistant. 

The addition polymerization of a vinyl monomer CH2=CHX involves three distinctly different steps. First, the reactive center must be initiated by a suitable reaction to produce a free radical or an anion or cation reaction site. Next, this reactive entity adds consecutive monomer units to propagate the polymer chain. Finally, the active site is capped off, terminating the polymer formation. If one assumes that the polymer produced is truly a high molecular weight substance, the lack of uniformity at the two ends of the chain—arising in one case from the initiation, and in the other from the termination-can be neglected. Accordingly, the overall reaction can be written... 

Polyester composition can be determined by hydrolytic depolymerization followed by gas chromatography (28) to analyze for monomers, comonomers, oligomers, and other components including side-reaction products (ie, DEG, vinyl groups, aldehydes), plasticizers, and finishes. Mass spectroscopy and infrared spectroscopy can provide valuable composition information, including end group analysis (47,101,102). X-ray fluorescence is commonly used to determine metals content of polymers, from sources including catalysts, delusterants, or tracer materials added for fiber identification purposes (28,102,103). 

The principal chemical markets for acetylene at present are its uses in the preparation of vinyl chloride, vinyl acetate, and 1,4-butanediol. Polymers from these monomers reach the consumer in the form of surface coatings (paints, films, sheets, or textiles), containers, pipe, electrical wire insulation, adhesives, and many other products which total biUions of kg. The acetylene routes to these monomers were once dominant but have been largely displaced by newer processes based on olefinic starting materials. 

In these equations I is the initiator and I- is the radical intermediate, M is a vinyl monomer, I—M- is an initial monomer radical, I—M M- is a propagating polymer radical, and and are polymer end groups that result from termination by disproportionation. Common vinyl monomers that can be homo-or copolymeri2ed by radical initiation include ethylene, butadiene, styrene, vinyl chloride, vinyl acetate, acrylic and methacrylic acid esters, acrylonitrile, A/-vinylirnida2ole, A/-vinyl-2-pyrrohdinone, and others (2). 

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