There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Hydrogels for tissue engineering.

https://yunus.hacettepe.edu.tr/~damlacetin/kmu407/index_dosyalar/4.%20makale.pdf

Biodegradable polymers as biomaterials

Hydrogels in pharmaceutical formulations.

Lithium (Li) metal is an ideal anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g−1), low density (0.59 g cm−3) and the lowest negative electrochemical potential (−3.040 V vs. the standard hydrogen electrode). Unfortunately, uncontrollable dendritic Li growth and limited Coulombic efficiency during Li deposition/stripping inherent in these batteries have prevented their practical applications over the past 40 years. With the emergence of post-Li-ion batteries, safe and efficient operation of Li metal anodes has become an enabling technology which may determine the fate of several promising candidates for the next generation energy storage systems, including rechargeable Li–air batteries, Li–S batteries, and Li metal batteries which utilize intercalation compounds as cathodes. In this paper, various factors that affect the morphology and Coulombic efficiency of Li metal anodes have been analyzed. Technologies utilized to characterize the morphology of Li deposition and the results obtained by modelling of Li dendrite growth have also been reviewed. Finally, recent development and urgent need in this field are discussed.

Lithium metal anodes for rechargeable batteries

We report here the first examples of poly(organophosphazenes) with side groups derived from the purines guanine and adenine and the pyrimidine cytosine. Polymers with these purines or pyrimidines as the only side groups proved difficult to synthesize by macromolecular substitution techniques because of the insolubility of the intermediate products. Therefore, cosubstitution reactions of the poly(dichlorophosphazene) with glycine ethyl ester, alanine ethyl ester, or diethylene glycol methyl ether, followed by the respective purine or pyrimidine, were utilized. Each pair of side groups was incorporated into the polyphosphazene in a 1:1 ratio. 31P NMR spectroscopy verified the replacement of all the chlorine atoms, while 1H and 13C NMR techniques confirmed the presence and ratio of the different side group. DRIFT spectroscopy indicated that the attachment of the purines or pyrimidines was via the primary amino functionality. Glass transition temperatures ranged from −28 to −15 °C for the mixed-substituent po...

Synthesis of Purine- and Pyrimidine-Containing Polyphosphazenes: Physical Properties and Hydrolytic Behavior

Structure of a new isopolymolybdate-cyclophosphazene complex

Reactions of steroid salts with hexachlorocyclotriphosphazene

Layer-by-layer (LbL) assembled films of poly[bis(methoxyethoxyethoxy) phosphazene] (MEEP) and poly (acrylic acid) (PAA) are demonstrated by utilizing the hydrogen bonding between these two polymers. These films show controlled thickness growth, high ionic conductivity, and excellent hydrolytic stability. The ionic conductivity of these films is studied by changing the assembly pH of initial polymer solutions and thereby controlling the hydrogen bonding characteristics. MEEP/PAA LbL films assembled at higher pH values have enhanced water uptake and transport properties, which play a key role in increasing ion transport within the films. At fully humidified conditions, the ionic conductivity of MEEP/PAA is 7 × 10−4 S cm−1, more than 1 order of magnitude higher than previously studied hydrogen-bonded LbL systems. Finally, free-standing films are isolated from low-energy surface substrates, which allows for bulk characterization of these thin films.

Harry R. Allcock

Papers

Synthesis of Purine- and Pyrimidine-Containing Polyphosphazenes: Physical Properties and Hydrolytic Behavior

Structure of a new isopolymolybdate-cyclophosphazene complex

Reactions of steroid salts with hexachlorocyclotriphosphazene

Ion conduction and water transport in polyphosphazene-based multilayers

Organosilicon derivatives of cyclic and high polymeric phosphazenes