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The polymerization of acrylamide initiated by ceric nitrate and 3‐chloro‐1‐propanol was studied in aqueous solution at 25°C. At constant hydrogen ion and nitrate ion concentration, the rate of polymerization was found to be independent of the ceric ion concentration. The molecular weight of the polymer was very low. To explain the data, a kinetic scheme is proposed whereby ceric ions are responsible for both initiation and termination. The rate constant for oxidative termination was found to be of the order of 105 l. mole−1 sec.−1 and varied with the hydrogen ion and the nitrate ion concentrations.

The rate of reaction of ceric nitrate with the 1,2‐glycol units and the alcohol units of polyvinyl alcohol was determined at 20°C. It was found that the glycol units are oxidized much faster than the alcohol units even though they are outnumbered about one hundred to one in the polymer chain. Under the conditions studied, at least 83 glycol units reacted per 100 hours oxidized. Since the oxidation of the glycol units is accompanied by chain splitting, the free radicals are produced predominantly at the fragments end.

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Triblock copolymers with surface-active properties, referred to as Pluronic, have shown potential medical applications such as drug delivery to selective targets in the human body. In particular, the transport of anti-inflammatory substances to the brain is required for illness treatment, thus the study of delivery agents that cross the blood-brain barrier is relevant. In this article we study the effects of the micelle formation on the morphologic and cytotoxic properties of Pluronic F68. We determinate the critical micellar concentration (CMC) by standard tensiometric and absorbance measurements, and also we analyze the morphology of polymers by atomic force microscopy. Our observations indicate that the morphological properties of F68 are drastically modified in the CMC range, as well as the ability to increase the viability of neuroblastoma cells maintained under culture conditions, as compared with nontreated cells. Our conclusions highlight the close correlation between morphological and physiochemical properties of Pluronic, which must be further understood in order to achieve highly controlled pharmacological uses.

Recent evidence has shown a correlation between the heat diffusion pathways and the known allosteric communication pathways in proteins. Allosteric communication in proteins is a central, yet unsolved, problem in biochemistry, and the study and characterization of the structural determinants that mediate energy transfer among different parts of proteins is of major importance. In this work, we characterized the role of hydrogen bonds in diffusivity of thermal energy for two sets of α-helices with different abilities to form hydrogen bonds. These hydrogen bonds can be a constitutive part of the α-helices or can arise from the lateral chains. In our in vacuo simulations, it was observed that α-helices with a higher possibility of forming hydrogen bonds also had higher rates of thermalization. Our simulations also revealed that heat readily flowed through atoms involved in hydrogen bonds. As a general conclusion, according to our simulations, hydrogen bonds fulfilled an important role in heat diffusion in structural patters of proteins.

A method has been devised for the rapid deposition of vinyl polymers within the fibers of cotton and viscose rayon fabrics. Polymerization is effected by means of a ceric ion-cellulose redox system. Two techniques of polymer deposition are described. A high order of rot and mildew resistance, comparable to that obtained by cyano ethylation, is achieved by polyacrylonitrile deposition. The deposition of polyacryloni trile, polyacrylamide, or polyniethyl acrylate results in no major improvement in the mechanical properties of the fabrics.

Polymerization of acrylonitrile in dilute aqueous solution initiated by the chloratesulfite redox was studied kinetically and with the aid of the electron microscope. Polymerization rate depended on the [ClO 3−] [H2SO3] product, the monomer content and the sodium lauryl sulfate concentration. The rate was depressed by agitation and by salts; it was accelerated by Fe++ and by Cu++ and was only moderately dependent on temperature. Particles of polymer separated from the start as spheroids less than 200 A. across and grew rather uniformly to 2000 to 3000 A. After a short time no new particles formed unless more initiator was added. Rate of polymerization per particle was reasonably constant. Salts and agitation led to aggregation of particles and polymerization rate was reduced. Sodium lauryl sulfate and Methocel had the opposite effect. The system bears a general resemblance to typical emulsion polymerization, and thus treatments based on homogeneous kinetics appear to be inadequate.