Otto Vogl

New developments in speciality polymers: polymeric stabilizers☆

Abstract Many new speciality polymers have been developed in the last few years. In this paper polymeric stabilizers (antioxidants, flame retardants and ultraviolet stabilizers) will be discussed. Polymeric antioxidants of the hindered-phenol type, copolymers of 2,6-ditertiarybutyl-4-vinyl(or isopropenyl)phenol with styrene, methyl methacrylate, or more importantly butadiene or isoprene have been prepared; hydrogenation of the latter copolymers gave copolymers of the two polymerizable phenolic antioxidants with ethylene or ethylene/propylene. The polymeric antioxidants have been blended with diene polymers and selected polyolefins and have improved the long-term oxidative stability of these polymers. Polymeric flame retardants have been prepared by copolymerizing styrene and/or acrylonitrile with acrylates and methacrylates of aliphatic bromine-containing alcohols or bromine-containing phenols. Polymers with polymer-bound flame retardants have a higher limiting oxygen index compared with the original polymer. A new class of polymerizable ultraviolet stabilizers has also been developed; these stabilizers are styryl, α-methylstyryl, acryloyl and methacryloyl derivatives of 2(2-hydroxyphenyl)2H-benzotriazoles. These monomers have been copolymerized with styrene, acrylates and methacrylates. 2(2-Hydroxyphenyl)2H-benzotriazoles substituted in the 4 position of the benzotriazole ring with hydroxyl, acetoxy or carboxyl groups suitable for incorporation into polyesters, polycarbonates, polyamides and epoxy resins have also been synthesized. All 2(2-hydroxyphenyl)2H-benzotriazole ultraviolet absorbers and the polymers into which they are incorporated have high light absorbency with γ max between 330 and 350 nm and extinction coefficients in some cases as high as 4.5 × 10 4 1 mol −1 cm −1 .

Polymeric Ultraviolet Absorbers

Abstract Plastics used in outdoor applications are exposed to the harmful solar radiation between 290 and 400 nm. Fortunately, the ozone layer of the outer atmosphere protects the earths surface from the higher energy radiation below 290 nm. The intensity of solar radiation at the surface of the earth is at a maximum in July and a minimum in January due to changes in the thickness of the ozone layer. The intensity also varies with the time of day, location, and weather conditions.

Oriental lacquer, poison ivy, and drying oils

From the oriental lacquer tree Toxicodendron vernicifluum, a sap (emulsion) is obtained the oil-soluble components (urushiol) of which consist of a mixture of 3-n-pentadecylcatechols and very small amounts of 3-n-heptadecylcatechols. Urushiol is the basis of oriental lacquer. The sap is conditioned by removal of most of the water by specific techniques, and the clear liquid is called oriental lacquer. It is used in the Orient for coatings to produce exquisite art objects. Poison ivy also has as its active ingredients 3-n-pentadecylcatechols, but they have a high diene content, which does not cure effectively. In humans 3-n-alkylcatechols cause severe contact dermatitis. The components of drying oils are glycerin esters of fatty acids derived from the families of palmitic (hexadecanoic) and stearic (octadecanoic) acids. In the case of the urushiols, as well as of the glycerides of drying oils, high unsaturation (60%) in the form of trienes in the long aliphatic chains is essential for curing.

Polyanion-polycation complex formation as a function of the position of the functional groups

Abstract A method consisting of the combination of turbidimetry and conductometry was investigated to detect polyanion-polycation complex formation. We used ‘strong acid’ polyelectrolytes varying in charge density and ‘strong basic’ polyelectrolytes varying in the length of the spacer groups and in the accessibility of the quaternary ammonium function. Our systematic investigations have shown a predominantly 1:1 stoichiometry at the turbidimetric as well as the electrochemical titration endpoints. Deviations were observed when the individual components were significantly less soluble, i.e. when the polymers had units with long hydrophobic spacer groups and/or with quaternary ammonium functions that are sterically less accessible. Colloid stability as well as the type of turbidity curve are discussed on the basis of a two-step mechanism of symplex formation. The results are also compared with our earlier investigations. We previously found a general trend that a 1:1 stoichiometry could only be achieved with ‘strong’ polyelectrolyte components. Independently of the molar ratio of the cationic to anionic functional groups at the titration endpoint, the stability of the colloids of the symplex system was found to depend also on the molar mass, the charge density and the hydrophobicity of the comonomer units.

Polymerization of higher aldehydes

Abstract This review concerns the polymerization of substituted aldehydes. Two groups of aldehydes have been subjected to systematic study: (1) higher aliphatic aldehydes containing linear chains with up to 12 carbon atoms; (2) branched hydrocarbon chains, including acetaldehyde; and haloaldehydes, derivatives of acetaldehyde substituted with fluorine, chlorine or bromine in the methyl group. The methods of preparation, purification and characterization of the monomers, the mechanisms of polymerization, their thermodynamics and stereochemistry, and the properties of the resulting polymers are all discussed. In addition it is pointed out that several properties exhibited by the polymers may lend themselves to practical applications in the future.

Addition polymers of aldehydes

The polymerization of aldehydes has played a considerable role in the progress of chain reaction polymerization and has significantly contributed to our knowledge of polymer science. Polyformaldehyde, as homopolymer and copolymer, plays an important role as a significant niche product in engineering plastics use. Higher aldehyde polymerization demonstrates the importance of stereospecificity and the ceiling temperature of polymerization. A discussion of haloacetaldehyde polymers is reserved for an upcoming article.

Haloaldehyde polymers: 32. Polymerization of chloral with lithium t-butoxide—stereochemistry of initiation and early propagation steps

Abstract Oligomeric addition products formed between lithium t-butoxide and one, two, three or more equivalents of trichloroacetaldehyde were trapped by acetylation and then identified by gas chromatography and proton nuclear magnetic resonance spectroscopy. Individual diastereomers were recognized. Product formation was found to be sensitive to both the addition and endcapping temperatures employed.

Functional polymers: 33. 2[2-hydroxy-4-acryloxy(methacr yloxy-phenyl]2H-4-methoxybenzotriazole monomers, polymers and copolymers

Abstract2(2,4-Dihydroxyphenyl)2H-benzotriazole has been prepared in about 50% yield by condensation ofo-nitrobenzenediazonium chloride with resorcinol followed by reductive cyclization of the initially obtained azo compound with zinc and sodium hydroxide. The condensation of the diazonium salt had to be carried out under carefully controlled conditions and in acidic medium, otherwise “bis”-condensation occurred which, after reductive cyclization, yielded 2(2,4-dihydroxyphenyl)1,3-2H-dibenzotriazole. 2(2,4-Dihydroxyphenyl)2H-benzotriazole was allowed to react with acryloyl or methacryloyl chloride. Monoacylation in the 4-position occurred by interfacial acylation technique and 2[2-hydroxy-4-acryloxy (or 4-methacryloxy)]2H-benzotriazole was obtained in over 60% yield. The two monomers were homopolymerized and copolymerized with styrene, methyl methacrylate, andn-butyl acrylate to polymers of high molecular weight. Incorporation of 2[2-hydroxy-4-acryloxy (or 4-methacryloxy)]2H-benzotriazole into the copolymer was from 1 to 10 mol% of the comonomer mixture. The ultraviolet spectra of monomers, homo- and copolymers were also determined.Zusammenfassung2(2,4-Dihydroxyphenyl)2H-benzotriazol wurde mit 50% Ausbeute über die Kondensation vono-Nitrobenzoldiazoniumchlorid mit Resorcin, gefolgt von reduktiver Cyclisierung der ursprünglich erhaltenen Azoverbindung mit Zn/NaOH, erhalten. Die Kondensation des Diazonium-Salzes hatte unter sorgfältig kontrollierten Bedingungen und im sauren Medium zu erfolgen, da ansonsten „Bis“-Kondensation auftrat, die nach der reduktiven Cyclisierung 2(2,4-Dihydroxyphenyl)1,3-2H-dibenzotriazol ergab. 2(2,4-Dihydroxyphenyl)2H-benzotriazol wurde mit Acryoyl- bzw. Methacryloylchlorid zur Reaktion gebracht, wobei die Monoacetylierungsprodukte in über 60% Ausbeute gewonnen wurden. Die beiden Monomeren wurden homopolymerisiert und mit Styrol, Methylmethacrylat undn-Butylacrylat zu Polymeren hohen Molekulargewichts copolymerisiert. Die Inkorporierung von 2[2-Hydroxy-4-acryloxy (bzw. 4-methacryloxy)]2H-benzotriazol in das Copolymer erfolgte zwischen 1 und 10 mol% der Comonomer-Mischung. Die UV-Spektren der Monomeren, Homo- und Copolymeren sind angegeben.

Syntheses of 5-Fluorouracil-Terminated Monomethqxypqly(Ethylene Glycol)S, Their Hydrolysis Behavior, and Their Antitumor Activities

Abstract The covalent attachments of 5-fluorouracil (5FU) units to poly(ethylene glycol) monomethoxy ether (MeO-PEG) attached through ester, amide, and ether bonds were carried out; three types of linkages were obtained through which 5FU units were attached to MeO-PEG. For the investigation of the release of the 5FU units, the homogeneous hydrolysis was investigated in vitro in the presence and absence of enzymes. Although the rate of release of l-β-carboxyethyl-5FU or 1-β-hydroxyethyl-5FU from the compounds was fast, the release of 5FU itself was slow. In addition, the antitumor activity of these three types of MeO-PEG-bound 5FU unit was tested in vivo by preliminary screening by the National Cancer Institute or by the Japanese Foundation for Cancer Research.

Polycationic salts as bile acid sequestering agents

Abstract A review of bile acid chemistry is included in this paper. The structures, chemistry, physiology and metabolism of the bile acids and their effects on the human body are discussed. Additionally, the precursor of bile acids are examined at length as are current treatments for diseases arising from high levels of cholesterol or the triglyceride carrying lipoproteins in blood plasma using bile-acid sequestering agents.