Polymer studies methanol

Polymer Properties. The modified polymers do exhibit some interesting properties. Water solubility is lost at 15% or less degree of substitution altho the polymers are at least partially soluble in acetic acid above about 25% degree of substitution. Solubility in butyrolactone also occurs above about 50% degree of substitution but the polymers are not soluble in xylene or methanol regardless of the degree of substitution. All polymers studied were soluble in DMSO, dimethylacetamide, dimethylform-... 

Binding studies revealed the high quality of the obtained cavities.Figure 5 shows the binding isotherm of the polymer in methanol.Various amounts of template have been offered to the polymer particles with free cavities and the amount of substance taken up was determined. The plot shows two distinct sections at ratios of template offered to free cavities below one, almost all of the template is bound to the polymer. At higher ratios, the isotherm directly levels off to a re-uptake of about... 

Polymer Studies. General Procedure. The desired amount of BPA (generally 45.35g), sodium or potassium hydroxide, phase transfer catalyst (Aliquat 336 or tetrabutylammonium bromide), p - t-butylphenol (0.75% as a chain stopper) and methylene chloride or methylene chloride/chlorobenzene (1/3) were heated at reflux for a period of 5 hr under nitrogen. At this point the reaction mixture was diluted with methylene chloride and filtered through Celite. The mixture was then either a) poured directly into methanol to precipitate the polymer or b) split into two portions one portion was precipitated by methanol, the second was reverse precipitated using methanol/acetone. (see below)... 

Commercial grades of PVP, K-15, K-30, K-90, and K-120 and the quaternized copolymer of vinylpyrrolidone and dimthylaminoethylmethacrylate (poly-VP/ DMAEMA) made by International Specialty Products (ISP) were used in this study. PEO standard calibration kits were purchased from Polymer Laboratories Ltd. (PL), American Polymer Standards Corporation (APSC), Polymer Standards Service (PSS), and Tosoh Corporation (TSK). In addition, two narrow NIST standards, 1923 and 1924, were used to evaluate commercial PEO standards. Deionized, filtered water, and high-performance liquid chromatography grade methanol purchased from Aldrich or Fischer Scientific were used in this study. Lithium nitrate (LiN03) from Aldrich was the salt added to the mobile phases to control for polyelectrolyte effects. 

Extensive studies of stereoselective polymerization of epoxides were carried out by Tsuruta et al.21 s. Copolymerization of a racemic mixture of propylene oxide with a diethylzinc-methanol catalyst yielded a crystalline polymer, which was resolved into optically active polymers216 217. Asymmetric selective polymerization of d-propylene oxide from a racemic mixture occurs with asymmetric catalysts such as diethyzinc- (+) bomeol218. This reaction is explained by the asymmetric adsorption of monomers onto the enantiomorphic catalyst site219. Furukawa220 compared the selectivities of asymmetric catalysts composed of diethylzinc amino acid combinations and attributed the selectivity to the bulkiness of the substituents in the amino acid. With propylene sulfide, excellent asymmetric selective polymerization was observed with a catalyst consisting of diethylzinc and a tertiary-butyl substituted a-glycol221,222. ... 

Polymer Degradation and Stability 75,No.l,2002,p.l85-91 STUDY ON METHANOLYTIC DEPOLYMERIZATION OF PET WITH SUPERCRITICAL METHANOL FOR CHEMICAL RECYCLING... 

In contrast to the results from previous studies with related monomers, at low temperatures, from —78 to —40°C, no polymerization reaction apparently occurred. However, if the polymerization reactions initiated with either BF3 0Et2 or SnCl were carried out at 0°C and the system was allowed to attain ambient temperature (20°C) over a period of 24 h, or if initiation was done directly at ambient temperature and stirring was continued for 24 h, good yields of low molecular weight polymers, which were insoluble in methanol, were obtained. The latter procedure was found to be the most effective, but at 0°C only viscous residues resulted. However, for shorter polymerization periods, even at 20°C, no products insoluble in methanol were obtained, and the monomer was recovered virtually unreacted. 

A phenomenological study was performed to determine the effect of solvent on Sn NMR spectra of these organoraetallic polymers. Samples were dissolved in chloroform, benzene, n-hexane, acetone, tetrahydrofuran, methanol, and pyridine. The Sn NMR spectra in these solvents are given in Figure 1. The appearance and location of the H Sn resonance changes drastically over the range of selected solvents. The chemical shift moves upfield in the order chloroform, benzene, n-hexane, acetone, tetrahydrofuran, pyridine, and methanol. The amount of structural information and, conversely, the broadening of the resonance increases in the same order with methanol and pyridine reversed. 

The zinc complex of 1,1,1,5,5,5-hexafluoroacetylacetonate forms coordination polymers in reaction with either 2,5-bis(4-ethynylpyridyl)furan or l,2-bis(4-ethynylpyridyl)benzene. The X-ray crystal structures demonstrate an isotactic helical structure for the former and a syndio-tactic structure for the latter in the solid state. Low-temperature 1H and 19F NMR studies gave information on the solution structures of oligomers. Chiral polymers were prepared from L2Zn where L = 3-((trifluoromethyl)hydroxymethylene)-(+)-camphorate. Reaction with 2,5-bis(4-ethy-nylpyridyl)furan gave a linear zigzag structure and reaction with tris(4-pyridyl)methanol a homo-chiral helical polymer.479... 

Water, methanol, and n-hexane do not influence the photooxidation of PVC (43), but the photodegradation is accelerated by ferric chloride (70,71) and certain other compounds containing iron (70,71,72). Purification of the polymer might be expected to enhance its photostability by removing deleterious impurities such as iron compounds that are derived from metal equipment. This type of result was obtained in one recent study (58) but not in others (30,59). In contrast, the photo-oxidative degradation of PVC should be enhanced by admixture of the polymer with materials that are unusually susceptible to photooxidation themselves. Such behavior has been observed for impact-modified PVC containing polybutadiene-based polyblends (69,73). 

The polymerization of 2-(diethylamino)ethyl methacrylate, DEAEMA, was studied under different conditions. It was shown that the best system providing narrow molecular weight distribution polymers involved the use of p-toluenesulfonyl chloride/CuCl/HMTETA as the initiator/catalyst/ligand at 60 °C in methanol [72]. Taking advantage of these results, well-defined PDEAEMA-fr-PfBuMA block copolymers were obtained. The synthesis was successful when either fBuMA or DEAEMA was polymerized first. Poor results with bimodal distributions were obtained when CuBr was used as the catalyst. This behavior was attributed to the poor blocking efficiency of PDEAEMA-Br and the incomplete functionalization of the macroinitiator. 

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