METHYLENE COPOLYMER

Synonyms Acetal resin Polyacetal Polyacetal copolymer Polyacetal resin Polyfonnaldehyde Polyot methylene copolymer POM Classification Thermoplastic polymer... 

Two of the perfluoropolyether fluid stmctures yet to be commercialized are interesting. The first stmcture is a strictly alternating copolymer of ethylene oxide and methylene oxide, which has the longest Hquid range of any molecule containing carbon (40). The second stmcture is the perfluoromethylene oxide polyether which has low temperature Hquid properties down to —120° C ... 

In 1975, the synthesis of the first main-chain thermotropic polymers, three polyesters of 4,4 -dihydroxy-a,a -dimethylbenzalazine with 6, 8, and 10 methylene groups in the aHphatic chain, was reported (2). Shortly thereafter, at the Tennessee Eastman Co. thermotropic polyesters were synthesized by the acidolysis of poly(ethylene terephthalate) by/ -acetoxybenzoic acid (3). Copolymer compositions that contained 40—70 mol % of the oxybenzoyl unit formed anisotropic, turbid melts which were easily oriented. 

Properties have been determined for a series of block copolymers based on poly[3,3-bis(ethoxymethyl)oxetane] and poly [3,3-bis(methoxymethyl)oxetane]- (9-tetrahydrofuran. The block copolymers had properties suggestive of a thermoplastic elastomer (308). POX was a good main chain for a weU-developed smectic Hquid crystalline state when cyano- or fluorine-substituted biphenyls were used as mesogenic groups attached through a four-methylene spacer (309,310). Other side-chain Hquid crystalline polyoxetanes were observed with a spacer-separated azo moiety (311) and with laterally attached mesogenic groups (312). 

The nmr spectmm of PVAc iu carbon tetrachloride solution at 110°C shows absorptions at 4.86 5 (pentad) of the methine proton 1.78 5 (triad) of the methylene group and 1.98 5, 1.96 5, and 1.94 5, which are the resonances of the acetate methyls iu isotactic, heterotactic, and syndiotactic triads, respectively. Poly(vinyl acetate) produced by normal free-radical polymerization is completely atactic and noncrystalline. The nmr spectra of ethylene vinyl acetate copolymers have also been obtained (33). The ir spectra of the copolymers of vinyl acetate differ from that of the homopolymer depending on the identity of the comonomers and their proportion. 

A waterborne system for container coatings was developed based on a graft copolymerization of an advanced epoxy resin and an acryHc (52). The acryhc-vinyl monomers are grafted onto preformed epoxy resins in the presence of a free-radical initiator grafting occurs mainly at the methylene group of the aHphatic backbone on the epoxy resin. The polymeric product is a mixture of methacrylic acid—styrene copolymer, soHd epoxy resin, and graft copolymer of the unsaturated monomers onto the epoxy resin backbone. It is dispersible in water upon neutralization with an amine before cure with an amino—formaldehyde resin. 

More recently, the copolymerization of ethyl cyanoacrylate with other 1,1 disubstituted electron deficient monomers and the effect of the monomers on adhesive properties have been studied. Monomers, such as diethyl methylene-malonate (DEMM), 8, were prepared [6,7]. Their homopolymers and copolymers... 

Replacement of a vinylidene fluonde unit by an e ylene or propylene unit in a locally perfluonnated cham environment greatly reduces the acidity ot the methylene hydrogens Copolymers of TFE and propylene are therefore considerably more resistant to bases and polar solvents than VDF-based elastomers TFE and propylene form a highly altematmg structure... 

The performance of several Sephacryl gel combinations is illustrated by results achieved for glucans from different types of starch granules. The applied Sephacryl gels of Pharmacia Biotech (15) are cross-linked copolymers of allyl dextran and N,N -methylene bisacrylamide. The hydrophilic matrix minimizes nonspecific adsorption and thus guarantees maximum recovery. Depending on the pore size of the beads, ranging between 25 and 75 im in diameter, aqueous dissolved biopolymers up to particle diameters of 400 nm can be handled. 

TABLE 16.3 Producers (Pharmacia Biotech) Specification of Fractionation Ranges of Cross-Linked Allyl Dextran/N,N -Methylene Bisacrylamide Copolymer-Based Sephacryl Gels for Dextrans... 

From the results obtained by thermal decomposition of both low-molecular weight vicinal dichlorides in the gas phase [74,75] and of the copolymers of vinyl chloride and /rthermal instability of PVC to the individual head-to-head structures. Crawley and McNeill [76] chlorinated m-1,4-polybutadiene in methylene chloride, leading to a head-to-head, and a tail-to-tail PVC. They found, for powder samples under programmed heating conditions, that head-to-head polymers had a lower threshold temperature of degradation than normal PVC, but reached its maximum rate of degradation at higher temperatures. 

The presence of three oxyethylene units in the spacer of PTEB slows down the crystallization from the meso-phase, which is a very rapid process in the analogous polybibenzoate with an all-methylene spacer, P8MB [13]. Other effects of the presence of ether groups in the spacer are the change from a monotropic behavior in P8MB to an enantiotropic one in PTEB, as well as the reduction in the glass transition temperature. This rather interesting behavior led us to perform a detailed study of the dynamic mechanical properties of copolymers of these two poly bibenzoates [41]. 

Random copolymers are similar to PEO but when the regular helical structure of the chains is demolished, the crystallinity is also destroyed. One of the simplest and most successful amorphous host polymers is an oxyethylene- oxymethylene structure in which medium length but statistically variable EO units are interspersed with methylene oxide groups. First described in 1990 [37], aPEO has the general structure... 

Kunitake, Yamaguchi and Aso149 studied the copolymerization of 2-furaldehyde with olefins and vinyl ethers using BF3 Et20 in methylene chloride or toluene at —78 °C. No copolymers were obtained with olefins, but p-tolyl vinyl ether or 2,3-dihydropyran gave polyethers. With the former co-monomer the values of the reactivity ratios were rx = 0.15 0.15 and r2 = 0.25 0.05 (Mj = 2-furaldehyde). 

More and more emphasis has recently been placed on the synthesis of fibre-forming AN copolymers containing reactive groups8. Among the monomers used to obtain reactive copolymers of considerable interest is diketene (1) (2-methylene-4-oxooxe-tane). 

Preparation of siloxane-carbonate segmented copolymers by interfacial polymerization involves the reaction of carboxypropyl-terminated siloxane oligomers with bisphenol-A and phosgene, in the presence of a strong base and a phase transfer catalyst, in water/methylene chloride solvent system l50 192), as shown in Reaction Scheme XIV. 

Isobutylene-based elastomers include HR, the copolymer of isobutylene and isoprene, halogenated HR, star-branched versions of these polymers, and the terpolymer isobutylene-p-methylene styrene-bromo-p-methyl styrene (BIMS). A number of recent reviews on isobutylene-based elastomers are available [33-35]. 

Ring-opening polymerization of 2-methylene-l,3-dioxepane (Fig. 6) represents the single example of a free radical polymerization route to PCL (51). Initiation with AIBN at SO C afforded PCL with a of 42,000 in 59% yield. While this monomer is not commercially available, the advantage of this method is that it may be used to obtain otherwise inaccessible copolymers. As an example, copolymerization with vinyl monomers has afforded copolymers of e-caprolactone with styrene, 4-vinylanisole, methyl methacrylate, and vinyl acetate. 

A fluid loss additive for hard brine environments has been developed [1685], which consists of hydrocarbon, an anionic surfactant, an alcohol, a sulfonated asphalt, a biopolymer, and optionally an organophilic clay, a copolymer of N-vinyl-2-pyrrolidone and sodium-2-acrylamido-2-methylpropane sulfonate. Methylene-bis-acrylamide can be used as a crosslinker [1398]. Crosslinking imparts thermal stability and resistance to alkaline hydrolysis. 

The spectra of copolymers of MMA and MAA are poorly resolved, and although the 0-methylene and o-methyl signals show structure, very little quantitative information is available. The butyl resonances at 0.8, 1.2, 1.3, and 1.6 ppm overwhelm the useful proton signals at the 0-methylene and o-methyl psoitions, i.e., the resolution is poor because of compositional sequencing. 

The previous sections in this chapter have tried to stress upon the significance of distribution of sequence lengths in polyethylene-based copolymers. The sequence length of interest in a system of ethylene-octene copolymers would be the number of methylene units before a hexyl branch point. As was discussed, this parameter has a greater impact on the crystallization behavior of these polymers than any other structural feature like branch content, or the comonomer fraction. The importance of sequence length distributions is not just limited to crystallization behavior, but also determines the conformational,... 

First, the short chain length PHAs, poly(HASCL), are composed of monomeric units containing up to 5 carbon atoms. The most well-known representatives are poly(3-hydroxybutyrate) (PHB), and its copolymers with hydroxyvalerate. Of all the PHAs, PHB is by far the most commonly encountered in nature [18]. It is the simplest PHA with respect to chemical structure, having a methylene (-CH3) group as the pendent R-unit in Fig. 1. Owing to its enzymatic synthesis, PHB has an exceptional stereochemical regularity. The chains are linear and the chiral centers all are in the R-stereochemical conformation, which implies that this polymer is completely isotactic. 

A carbazole-functionalized norbornene derivative, 5-CN-carbazoyl methy-lene)-2-norbornene, CbzNB, was polymerized via ROMP using the ruthenium catalyst Cl2Ru(CHPh)[P(C6Hii)3]2 [100]. The polymerization was conducted in CH2C12 at room temperature, to afford products with polydispersity indices close to 1.3. Subsequent addition of 5-[(trimethylsiloxy)methylene]-2-norbornene showed a clear shift of the SEC trace of the initial polymer, indicating that a diblock copolymer was efficiently prepared in high yield. 

A final example is the synthesis of H-shaped copolymer of (PS PEG (PS)2 by ATRP, i.e. [209]. The synthetic strategy involves the synthesis of 2,2-bis(methylene a-bromopropionate) propionyl chloride (1), the preparation of 2,2-bis(methylene a-bromopropionate) propionyl-terminated poly(ethylene glycol) (BMBP-PEG-BMBP) (2), and then ATRP of styrene at 110 °C with BMBP-PEG-BMBP/CuBr/2,2/-bipyridine as the initiating system. The structure (3) was configured by using NMR and SEC measurements (Scheme 116). 

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