Field poly

In Industrial Chemicals. Recendy, as some amino acids (eg, L-glutamic acid, L-lysine, glycine, DL-alanine, DL-methionine) have become less expensive chemical materials, they have been employed in various appHcation fields. Poly(amino acid)s are attracting attention as biodegradable polymers in connection with environmental protection (236). 

Electric field Poly(2-hydroxyethyl methacry- Propranolol... 

At first, diarsenic triselenide was used as the photoconducting material. Poly(A -vinyl carbazole) is now used. This polymer absorbs ultraviolet light, producing an exciton, which ionizes in an electric field. Poly(vinyl carbazole) behaves as an insulator in visible light, but can, however, be sensitized with certain electron donors to form a charge transfer complex. 

Stimuli-responsive polymers have been attracting a lot of attention and have been applied to a variety of fields. Poly(vinyl methyl ether) (PVME) undergoes a phase transition at around 38 °C, going from a fully hydrated water soluble polymer at... 

It is not the purpose of this book to discuss in detail the contributions of NMR spectroscopy to the determination of molecular structure. This is a specialized field in itself and a great deal has been written on the subject. In this section we shall consider only the application of NMR to the elucidation of stereoregularity in polymers. Numerous other applications of this powerful technique have also been made in polymer chemistry, including the study of positional and geometrical isomerism (Sec. 1.6), copolymers (Sec. 7.7), and helix-coil transitions (Sec. 1.11). We shall also make no attempt to compare the NMR spectra of various different polymers instead, we shall examine only the NMR spectra of different poly (methyl methacrylate) preparations to illustrate the capabilities of the method, using the first system that was investigated by this technique as the example. 

PPO poly(phenyl oxide) SCF self-consistent field ... 

Polymer Ferroelectrics. In 1969, it was found that strong piezoelectric effects could be induced in the polymer poly(vinyhdene fluoride) (known as PVD2 or PVDF) by apphcation of an electric field (103). Pyroelectricity, with pyroelectric figures of merit comparable to crystalline pyroelectric detectors (104,105) of PVF2 films polarized this way, was discovered two year later (106.)... 

Poly(ethylene oxide). The synthesis and subsequent hydrolysis and condensation of alkoxysilane-terniinated macromonomers have been studied (39,40). Using Si-nmr and size-exclusion chromatography (sec) the evolution of the siUcate stmctures on the alkoxysilane-terniinated poly(ethylene oxide) (PEO) macromonomers of controlled functionahty was observed. Also, the effect of vitrification upon the network cross-link density of the developing inorganic—organic hybrid using percolation and mean-field theory was considered. 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

Poly(vinyl cinnamate) is not used in the traditional areas of plastics technology but its ability to cross-link on exposure to light has led to important applications in photography, lithography and related fields as a photoresist. 

The first methacrylic esters were prepared by dehydration of hydroxyisobutyric esters, prohibitively expensive starting points for commercial synthesis. In 1932 J. W. C. Crawford discovered a new route to the monomer using cheap and readily available chemicals—acetone, hydrocyanic acid, methanol and sulphuric acid— and it is his process which has been used, with minor modifications, throughout the world. Sheet poly(methyl methacrylate) became prominent during World War II for aircraft glazing, a use predicted by Hill in his early patents, and since then has found other applications in many fields. 

The chemical name for such materials is poly(bisbenzimid-azobenzophenan-throlines) but they are better known as BBB materials. Such polymers have a Tg in excess of 450°C and show only a low weight loss after aging in air for several hundred hours at 370°C. Measurements using thermal gravimetric analysis indicate a good stability to over 600°C. The main interest in these materials is in the field of heat-resistant films and fibres. 

By 1988, a number of devices such as a MOSFET transistor had been developed by the use of poly(acetylene) (Burroughes et al. 1988), but further advances in the following decade led to field-effect transistors and, most notably, to the exploitation of electroluminescence in polymer devices, mentioned in Friend s 1994 survey but much more fully described in a later, particularly clear paper (Friend et al. 1999). The polymeric light-emitting diodes (LEDs) described here consist in essence of a polymer film between two electrodes, one of them transparent, with careful control of the interfaces between polymer and electrodes (which are coated with appropriate films). PPV is the polymer of choice. 

A number of examples have been studied in recent years, including liquid sulfur [1-3,8] and selenium [4], poly(o -methylstyrene) [5-7], polymer-like micelles [9,11], and protein filaments [12]. Besides their importance for applications, EP pose a number of basic questions concerning phase transformations, conformational and relaxational properties, dynamics, etc. which distinguish them from conventional dead polymers in which the reaction of polymerization has been terminated. EP motivate intensive research activity in this field at present. 

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