Poly(organophosphazenes) with poly(alkyl ether) side groups: a study of their water solubility and the swelling characteristics of their hydrogels

Abstract

Five different poly[(alkyl ether)phosphazenes] were synthesized for studies of their water solubility as well as the swellabilities of their corresponding hydrogels in aqueous media. They are poly-[bis(methoxyethoxy)phosphazene],poly[bis[(aminoethoxy)ethoxy]phosphazene],poly[bis[(methoxyethoxy)ethoxy] phosphazene], poly[bis[(ethoxyethoxy)ethoxy]phosphazene], and poly [bis [ (butoxyethoxy)ethoxy]phosphazene].Lower critical solution temperatures (LCST) were detected for four of the polymers. This phenomenon was independent of polymer concentration. However, poly[bis[(aminoethoxy)ethoxy]phosphazene] possessed no LCST in aqueous media and remained fully soluble at all polymer concentrations. Hydrogels of these polymers were prepared by subjecting them to y radiation (1, 5, and 10 Mrad). The cross-linked polyphosphazenes behaved in a manner similar to that of their soluble counterparts. As the temperature of the aqueous media was increased, the hydrogels became opaque and released water. During these experiments, the percentage of water lost by the hydrogels was independent of both the pH of the aqueous media and the radiation dose received by the gels. No detectable decomposition of the soluble polymers was found nor was any loss of integrity of the hydrogels detected through several heating and cooling cycles. This solubility phenomenon was characteristic only of the interaction with water and was not detected in organic solvents. The potential biomedical applications of these materials are discussed.

A water‐soluble amphoteric copolymer: Synthesis and its dispersion properties on cement particles

“…The synthesis of a mixed‐substituent polyphosphazene PNEG 50 MEEP 50 was confirmed by multinuclear NMR, DSC, and molecular weight determination. The polymer showed a T g of −58°C, which was 26°C higher than that of the single‐substituent MEEP due to the presence of glycine groups 21. Furthermore, the glycine‐based PPHOS have been shown to be highly osteocompatible for bone tissue engineering15, 16 and can provide hydrogen bonding sites when blended with PLAGA to achieve miscible systems with neutral degradation products and controlled degradation rates 13, 16, 17, 19, 20.…”

Crosslinking Reactions for the Conversion of Polyphosphazenes into Useful Materials

“…Table 1, are unusual in the sense that they show a lower critical solution temperature (LCST) in water. 83 This means that the polymers, although soluble in water at room temperature, nevertheless precipitate from solution as the temperature is raised above the LCST (Figure 11). The phenomenon is a consequence of the amphiphilic nature of polymers in which the backbone nitrogen atoms and the side group oxygens are hydrophilic, but the CH 2 groups and terminal CH 3 units are hydrophobic.…”

Ring-Opening Polymerization—An Introductory Review

“…They are thus very suitable for special automotive and aerospace applications [172][173][174][175] and have also been suggested for biostable biomedical devices [176] Polphosphazenes with oligo-ethylene oxy side chains have also been considered for use in lithium-ion polymer batteries [177][178][179] and those with sulfonated aryloxy side groups as membranes for fuel cells [180]. Polyphosphazenes with ethylene oxy side groups can be crosslinked with γ-rays to give hydrogels, which have been investigated as controlled drug release agents [181][182][183][184][185]. Polyphosphazenes with amino acid side chains are biodegradable and can be employed to aid the regeneration of bone tissue in vivo [186][187][188][189].…”