Homopolymer solution polymerization

The Phillips-type catalyst can be used in solution polymerization, slurry polymerization, and gas-phase polymerization to produce both high density polyethylene homopolymers and copolymers with olefins such as 1-butene and 1-hexene. The less crystalline copolymers satisfy needs for materials with more suitable properties for certain uses that require greater toughness and flexibiUty, especially at low temperatures. 

The glass-transition temperature in amorphous polymers is also sensitive to copolymerization. Generally, T of a random copolymer falls between the glass-transition temperatures of the respective homopolymers. For example, T for solution-polymerized polybutadiene is —that for solution-polymerized polystyrene is -HlOO°C. A commercial solution random copolymer of butadiene and styrene (Firestone s Stereon) shows an intermediate T of —(48). The glass-transition temperature of the random copolymer can sometimes be related simply as follows ... 

Polymers Polyacrylamide and hydrolyzed polyacrylamide were prepared by the American Cyanamid Company specifically for this project, starting with l C labelled monomer. The radioactivity level of the monomer was kept below 0.20 mC /g in order to avoid significant spontaneous polymerization, utilizing a copper inhibitor. The homopolymer was synthesized by free radical solution polymerization in water at 40°C, using monomer recrystallized from chloroform, an ammonium persulfate-sodium metabisulfite catalyst system, and isopropanol as a chain transfer agent. Sodium... 

A new method for the syntheses of fluorocarbon polyarylate polymers has been demonstrated. The chemistry utilizes the [2jt+2rr] cyclodimerization of fluorinated olefins and generates polymers of novel composition. The first generation of polymers prepared by this method are polyarylate homopolymers. Theremoplastic polymers of high molecular weight can be achieved via neat or solution polymerization. One example of a thermoset polymer prepared by this method has a high Tg, low dielectric constant and dissipation factor, low moisture... 

IPN s and related materials) in fact) have a long history. For example) IPN s were first synthesized to produce smooth sheets of bulk polymerized homopolymers (11), IPN s were next used as solution polymerized ion exchange resins. (12) 13) Further development of IPN s included the syntheses oT interpenetrating elastomer networks (lEN s) and simultaneous interpenetrating networks (SIN s) (14). lEN s consist of a mixture of different emulsion polymerized elastomers which are both crosslinked after coagulation. SIN s are formed by the simultaneous polymerization of mixed monomers by two noninterfering reactions (3 ) 16). 

The development of unsaturated polyanhydrides responded to the necessity of improving the mechanical properties of the polymers in applications such as the temporary replacement of bone. " Unsaturated polyanhydrides, prepared by melt or solution polymerization, include homopolymers of fumaric acid (FA), acetylene-dicarboxylic acid (ACDA), and 4,4 -stilbenzenedi-carboxylic acid (STDA). The chemical structures of poly(FA) and poly(ACDA) are shown in Table 1. These polymers are highly crystalline and insoluble in common organic solvents. The double bonds of these monomers make them suitable for further crosslinking to improve mechanical properties of polyanhydrides. When copolymerized with aliphatic diacids, less crystalline polymers with enhanced solubility in chlorinated solvents result. 

Polymerizations. Homopolymer DADMAC-Solution Polymerization. To a 1-L four-neck resin pot equipped with a mechanical stirrer, thermometer, condenser, purge tube, and heat regulating device were added 492 g of 55% aqueous DADMAC monomer. The pH was adjusted to 6.0 with dilute hydrochloric acid, heated to 50°C, and purged with nitrogen for 1 hr while stirring. Then, 0.05% Na4 EDTA (based on weight reaction mix) was added followed by 1.5 X 10 2 mol f-butyl-peroxypivalate/mol monomer. The temperature was maintained at 50°C 2°C for 18 hr, at which time the monomer conversion to polymer leveled off at 95%. The polymer was isolated via acetone precipitation. 

Homopolymer DADMAC-Emulsion Polymerization. The equipment setup outlined in the solution polymerization was used to prepare the emulsion polymer. To the resin pot 321.5 g benzene, 138.5 g of 72.2% aqueous DADMAC monomer, and 40 g of 20% aqueous sodium octyl phenoxyethoxy-2-ethanol sulfate were added. The mixture was stirred at 170-180 rpm with a paddle stirrer and heated to 50° 1°C. The suspension was purged with nitrogen gas for 1 hr. Then, 7 ppm Fe+2 (added as Fe(NH4)2(S04)3 6H20) were added, followed by 2 X 10"3 mol f-butylperoxypivalate/mol monomer. The reaction mixture was stirred for 20 hr at 50° 1°C under a nitrogen blanket. The polymer conversion after 20 hr was 90 2%. The product was isolated by adding the benzene emulsion to acetone, filtering the product, and drying. 

Homopolymer AMBTAC-Solution Polymerization. The equipment setup was the same as in the previous sections. After adjusting the pH to 9.5, a 35% aqueous solution of AMBTAC monomer was added to the reactor. The monomer solution was heated to 35 = = 1°C and purged with nitrogen gas for 1 hr. Then, 1.5 X 10"3 mol f-butylperoxypivalate/ mol monomer was added. The solution was maintained at 35 5°C for 4 hr, at which point more than 95% conversion was achieved. The product was isolated by acetone precipitation. 

Figure 7. AMBTAC homopolymer mol % MBA vs. filter time (%) emulsion polymerized (A) solution polymerized...

Vinyl solution resins are usually made via suspension or solution polymerization techniques. Plastisols are defined as suspensions of homopolymers or copolymers in nonaqueous liquids. The liquids, which are normally vinyl plasticizers, are selected so that they do not solvate the polymer to any extent at room temperature. The suspension is maintained by residual emulsifier left on the particle, and the very small particle size of the polymer itself (all pass through a 200-mesh screen). A finite quantity of plasticizer must be present in order to form the plastisol or "paste" no plasticizer, no plastisol. As with all vinyl systems, consideration may have to be given to plasticization, heat and light stabilization, pigmentation, etc. 

In a case of synthesis of PBA homopolymer, the polymerization was carried out at 70 °C. DMDBrHD (56.6 pL, 0.26 mmol), PMDETA (54.4 pL, 0.26 mmol), BA (11 mL, 78 mmol), and anisole (1.1 rtiL) were added to a 25-mL Schlenk flask eqtripped with a magnetic stir bar. The flask was sealed, and the resulting solution was subjected to three freeze-pump-thaw cycles. After equilibration at room temperatrrre, CuBr (37.3 mg, 0.26 mmol) was added to the solution tmder nitrogen flow and the flask was placed in preheated oil bath. Aliquots were removed by syringe in order to monitor molectrlar weight evolution. After a predetermined time, the flask was removed from the oil bath and opened to expose the catalyst to air. The polymerization solution was diluted with CHCI3 and passed over an alumina (activated neutral) coltrrrm to remove the catalyst. Solvent was removed by rotary evaporation, and the polymer was isolated by precipitation into cold methanol. 

Commercially, by far the biggest amount of poly(vinyl chloride) homopolymer is produced by suspension polymerization and, to a lesser extent, by emulsion and bulk polymerization. Very little polymer is formed by solution polymerization. 

The methacrylate group of lEM allows it to be free radical polymerized Thomas (1) reports lEM can be solution polymerized in dry solvents using AIBN (azobis-isobutyronitrile) initiator to give a stable polyisocyanate. The homopolymer of lEM retains 90-95% of its isocyanate functionality and has a glass transition... 

Bulk thermal polymerization yielded polymer which was only partially soluble and softened at 210 C. Concentrated solution polymerization produced polymer with T of 190 (DSC) which was soluble in chloroform and less brittle Since it was impossible to machine homopolymer samples, we decided to copolymerize the lead-containing monomer with isopropylstyrene, acrylonitrile, lauryl methacrylate and octadecyl methacrylate. Acrylonitrile was chosen because it generally produces copolymers with styrene with impact strength superior to polystyrene. The other monomers were selected because they have bulky side chains which would act as internal plasticizers. The methacrylate monomers contain oxygen, which was avoided in the selection of the high-Z-containing monomers, so the quantities added were kept to a minimum. 

In our original studies we found that insoluble polymeric materials result from thermal polymerizations of neat liquid borazine and only when polymerizations were carried out in the presence of added borazine could soluble polymers be obtained. We have now examined alternative methods and conditions for inducing vinylborazine polymerizations and have recently found that soluble poly(vinylborazine) homopolymers can be readily obtained by solution polymerization with the free radical initiator AIBN. 

A third class of new polymer integral equation theories have been proposed by Kierlik and Rosinberg. Their work is an extension of a density functional theory of inhomogeneous polyatomic fluids to treat the homogeneous phase. The Wertheim thermodynamic pertubation theory of polymerization is employed in an essential manner. Applications to calculate the intermolecular structure of rather short homopolymer solutions and melts have been made. Good results are found for short chains at high densities, but the authors comment that their earlier theory appears to be unsuited for long chains at low to moderate (semidilute) densities. ... 

Polyvinyl chloride (PVC) is a homopolymer of vinyl chloride. Eighty percent of commercial PVC in packaging is produced by chain-reaction polymerization using a suspension method. Other methods are emulsion and solution polymerization. Chain-reaction polymerization requires initiators to produce free radicals, then the reaction proceeds until the chain is terminated. The predominant configuration of the monomer in the polymer chain follows a head-to-tail alignment to yield a syndiotactic polymer. 

Figure 15 documents that volume additivity (eq. 41) and additivity of flexible bonds (eq. 42) do not describe the data. Specific interactions as in equation 44 are needed (128). While equations 40 to 44 are often used indiscriminately for homopolymer solutions and copol3rmers, it was shown that sequence distributions in copol3maers, as given by polymerization kinetics, can also be of influence on the glass transition (129,130). 

The production of polymers and copolymers of isobutylene was described in Section 5.3 as an example of solution polymerization with insoluble polymer. The lower molecular weight homopolymers are used in adhesives and the copolymer with isoprene is a commercial rubber. 

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. 

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