Ionization, polymer-bearing

Conjugated polymers are powerfiil fluorescent materials, which makes them suitable for applications as chemical sensors. Chart 13.1 presents the structures of some typical polymers that are applicable for the detection of analytes at low concentrations. These polymers include poly(p-phenylene ethynylene), PPE poly(p-phenylene vinylene), PPV polyacetylene and polyfluorene. Those polymers bearing ionizable pendant groups are water-soluble polyelectrolytes. 

A common behavior in biopolymers is the pH-responsive conformation change. The pH-responsive polymers can accept and donate protons in response to environmental pH changes. The degree of ionization alters dramatically upon pH change in a polymer bearing weakly ionizable groups, causing the transfer of the hydrodynamic volume of the polymer chains. There are two types of pH-responsive polymers weak... 

In the absence of free water, pure sulfuric and phosphoric acids undergo self-ionization. Addition of water, as a proton receptor, promotes the dissociation of the acids. Polymers bearing basic sites, such as ether, alcohol, imine, amide, or... 

In both cataphoretic and anaphoretic resists an ionized polymer acts as a surfactant to emulsify itself and the other resist ingredients in water. The resulting micelles are typically of the order of 50-200 nm in diameter and bear a surface charge. A typical micelle in a cataphoretic emulsion, surrounded by a diffuse layer of counter-ions, is shown in Fig. 2.1. 

Very recently, a polymer-supported construct for quantifying the reactivity of monomers involving multicomponent Ugi strategies was reported [53]. The authors investigated the Ugi four-component condensation of a set of aldehydes, acids, and isonitriles. The amine compound used was bound to a specially modified Rink amide polystyrene resin bearing an ionization leveler and bromine functionality as a mass splitter for accurate analysis by positive electrospray ionization mass spectrometry. The microwave-assisted experiment was performed with a set of ten carboxylic acids, hydrocinnamaldehyde, and cyclohexyl isonitrile in DCM-... 

A series of star DHBCs were evaluated for their ability to transfect hmnan cervical HeLa cancer cells with the modified plasmid pRLSV40, bearing the enhanced green fluorescent protein as the reporter gene [55]. The copolymers utilized were composed of PDMAEMA and PHEGMA blocks (where PDMAEMA is an ionizable block, while PHEGMA is a non-ionic water soluble block). The experimental data indicate a decreased toxicity for the star copolymer, compared to a reference PDMAEMA star homopolymer, for the same amounts of star polymer tested. Moreover, it has been found that the architecture of the star copolymer, i.e. star block, miktoarm star etc, plays a decisive role on the transfection efficiency. The best performance, for all star copolymers tested, was observed for a star block copolymer with... 

In the early stages of ESR application to polymer research, many studies on the identification of free radicals produced by irradiation with ionizing radiation, x-ray, and ultraviolet light were made. Some of the irradiation effects in polymeric materials were considered to originate from the radical processes and, therefore, clear identification of the radicals trapped in irradiated polymers was one of the most important problems at that stage. In this meaning, ESR application was considered to be a very convenient technique for this purpose, because detection and identification of the free radicals bearing unpaired electrons in principle can be done easily by the ESR method without any chemical modification of the materials. 

---