Haloaldehyde Polymers. XIV. Endgroups in Polychloral

Chloral polymers prepared by anionic polymerization have alkoxide endgroups as terminal ends at the end of this polymerization. The initiating anion has, as expected, no influence on the type of terminal group formed. Polychloral with terminal alkoxide ends degrades easily thermally to monomeric chloral. Alkoxide endgroups in polychloral do not readily react with alkylating or acylating agents, although partial stabilization has been observed when alkoxide-terminated polymers were allowed to stand for periods of time; the endgroups seem to react either with impurities or with excess chloral in side reactions. With protic acids, alkoxide-terminated polychloral is transformed into hydroxyl-terminated polymer of higher thermal stability. Studies of the initiation step of the chloral polymerization revealed that above the ceiling temperature of polymerization, strong nucleophiles, such as soluble tertiary butoxide, initiate quantitatively, but polymerization does not proceed until the mixture is cooled. When chloral is initiated with weaker nucleophiles such as chloride or carboxylates, the initiation equilibrium is not on the side of the initiated species, although it shifts effectively as polymerization proceeds; with carboxylates as initiators the ester group has been found incorporated as the initial endgroup in polychloral. With sufficient amounts of lithium tertiary butoxide as anionic initiator, polychloral of low molecular weight was prepared. This polymer does not react with end-capping reagents (other than PCl₅) as does high molecular weight polychloral; in spite of considerable effort it was not possible to prepare low molecular weight soluble polychloral or oligomeric polychloral. Polychloral prepared with cationic initiators is thermally more stable than unstabilized anionically initiated polychloral but is generally crumbly and incoherent. The end-groups of such polymers are usually hydroxyl endgroups. Identification of endgroups of the polymers has been done where possible by IR spectroscopy, for the initiation reaction by NMR spectroscopy, but for high molecular weight insoluble polymers almost exclusively by comparative thermal polymer degradation.     

Polymers for the 21st Century

Abstract

In the 21st century, polymers will be even more in demand for our modern societal needs than they are today. From the high volume commodity plastics to the highly sophisticated, highly priced, and specially designed low volume functional specialty polymers, an entire rainbow of needs and application possibilities awaits the polymers of the future. In some cases new and improved manufacturing techniques or improvements in the life cycle of these materials will be needed. In other cases completely new polymer structures and their morphologies will have to be developed.     

Functional Polymers. III. Endcapping and Substitution on Polymers with Compounds Containing Ultraviolet-Absorbing Groups

Endcapping of oligo(oxyethylene) glycols was carried out by transesterification of methyl N,N-dimethylaminobenzoate with sodium methoxide as the catalyst or by the reaction of sodium salicylate with the ditosyl ester of the oligo(oxyethyl-ene) glycols. Several other common reactions were tried for the endcapping of the oligo(oxyethylene) glycols but were found to be either more cumbersome or unsuccessful. All products were obtained in high yield and high purity. The reactions of tetraalkylammonium carboxylates with aliphatic halides were found to be very general and mild reactions for the preparation of esters in high yield and high purity. It was found that these reactions could be utilized for the preparation of esters on polymers even if the carboxylate group was directly attached to the polymer chain. It was also demonstrated that the aliphatic halide group could be on the polymer, as in the case of polyepichlorohydrin. Copolymers of epichlorohydrin and glycidyl N,N-dimethylaminobenzoate with up to 90% glycidyl benzoate as the comonomer were prepared, and poly(tetra-butylammonium methacrylate) was effectively transformed with 4-(2-bromoethoxy)-2-hydroxybenzophenone into the corresponding ester. The products were characterized by the usual spectral means.     

A Practical Synthesis of Tetrachloroethylene Oxide

Tetrachloroethylene oxide has been synthesized by direct oxidation of tetrachloroethylene with oxygen in the presence of ultraviolet light. This preparation resulted in a mixture of tetrachloroethylene oxide and trichloroacetyl chloride in approximately equal amounts under the most favorable conditions. Tetrachloroethylene oxide rearranges readily to trichloroacetyl chloride above 60 C with an activation energy E of 3.0 × 10⁴ cal/mole and a pre-exponential factor A of 1.9 × 10¹³. All attempts to polymerize tetrachloroethylene oxide under a variety of conditions failed.     

In Memoriam: Herman F. Mark. May 3, 1895-April 6, 1992

Abstract

Professor Herman F. Mark died on April 6, 1992, one month before his 97th birthday. For almost 70 years Herman Mark was in the forefront of polymer chemistry. He was an outstanding scientist, a superb teacher, a fascinating lecturer, an excellent organizer, and a remarkable human being. In the early days of his scientific career he determined the crystal structures of cellulose and a number of other natural and synthetic polymers. He also played a leading role in the develop- ment of the kinetic theory of rubber elasticity, and he was responsible for the simple determination of polymer molecular weights based on viscosity measurements, as represented by the Mark-Houwink equation. What Mark did not actively investi- gate himself, he helped disseminate throughout the rapidly developing field of poly- mer science.     

Photochemical Behavior in Copolymers of 2(2-Hydroxy-5-vinylphenyl)2H-benzotriazole and Methyl Methacrylate: Photochemical Processes in Polymeric Systems. 6

The photochemical behavior of poly[2(2-hydroxy-5-vinylphenyl)2H-benzotriazole)]-co-methyl methacrylate was studied by spectroscopic and analytical techniques; no degradation of this copolymer occurred when the bulk polymer was exposed for several thousand hours of accelerated aging by ultraviolet irradiation. However, by the end of the period, surface deterioration became noticeable. Picosecond flash photolysis on copolymer solutions demonstrated that the lowest energy excited singlet state undergoes rapid internal conversion with little or no triplet yield. The observed short singlet lifetime (～25 ps) is undoubtedly responsible for the photostability of this copolymer system. Analysis of the surface exposed to ultraviolet irradiation indicates some photooxidative degradation of the methyl methacrylate portion of the copolymer, but the surface 2(2-hydroxy-5-vinylphenyl)2H-benzotriazoles of the macromolecules remain unchanged.     

Glycosylhydrazides,a New Class of Sugar Surfactant. Preparation and Amphiphilic Properties of 1-Glycosyl-2-Acylhydrazines

ABSTRACT

The synthesis and the amphiphilic properties of 1-glycosyl-2-acylhydrazines are described. This new class of surfactants, referred to as glycosylhydrazides, is easily available from a reducing sugar and hydrazides without protection. Seven hydrazides having an alkyl chain of up to fourteen carbon atoms, are coupled with glucose giving 1-glucosyl-2-acylhydrazines in good yields; 1-maltosyl-2-octanoylhydrazine, as a typical disaccharide-based surfactant, is prepared as well. Critical micellar concentrations of these surfactants range from 0.04 to 252 mM.     

My life with polymer science

This article describes the scientific investigations and accomplishments in the life of the author. After a dissertation on steroids, several years were spent on alkaloids and research on heterocyclic compounds. Much of the author's career was devoted to research on aldehyde polymerization, the discovery of the polymerization of higher aldehydes and their isotactic polymers, and haloaldehyde polymerization. The latter led to our work on the ceiling temperature of polymerization, on new polymerization techniques [involving the ceiling temperature and the concept of macromolecular asymmetry (polymer helicity)], and the genesis of chloral polymerization. Another important period was devoted to functional polymers, polymeric stabilizers, and polymeric drugs. Other research activities included studies of unusual polymers, head-to-head polymers, spacer groups in polymers, and oriental lacquers. Attention was also paid to the use of novel and unusual polymer intermediates, polymerization under extreme conditions and the preparation and behavior of uncommon polymer structures. Finally, it was recognized that macromolecules can be categorized with increasing frequency as polymers with broad and narrow molecular weight distributions and uniform polymers. The ultimate unity is isotopically pure uniform polymers, single macromolecular species. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 795–818, 2004     

Transformations and recognition of platinum-DNA adducts: recent developments

Transition Metal Chemistry -