China 
Africa 
Explore chapters and articles related to this topic
Novel Elastomers for Biomedical Applications
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
The physical properties of polyphosphazene depend on the nature and the number of substitutes. However, the flexibility of the P–N backbone is the property in common. Because of the weakness of the rotation energy around the N–P bond (3.38 and 21.8 kJ/mol, respectively for polyditrifluoroethoxy and polydiphenoxyphosphazene),148 the structure of polyphosphazene has a high degree of freedom and a low glass transition temperature. Small and unhindered substituents such as alkoxys give very low Tg, below –60°C (–105°C for n-butyl). Aromatic rings give more stiffness, leading to a transition temperature of between –34°C and 0°C with one ring and between 0°C and 100°C with two rings.149 The freedom of movement of the chains can also be limited by interatomic interactions. This is particularly true of primary amine substituted polymers which exhibit a Tg about 100°C higher than for polymers substituted with the corresponding alcohols. This effect is explained by segment immobilization due to hydrogen bonding. The P–N backbone flexibility can also make these polymers undergo structure changes in the solid state.150
Biodegradable Hydrogels: Tailoring Properties and Function through Chemistry and Structure
Published in Joyce Y. Wong, Joseph D. Bronzino, Biomaterials, 2007
Andrew T. Metters, Chien-Chi Lin
As a degradable synthetic hydrogel for biomedical applications, polyphosphazene has gained much attention for controlled drug release. Readers are referred to recent review articles for a more in-depth discussion of polyphosphazene polymers [Andrianov and Payne, 1998]. Unlike most of the other synthetic polymers with carbon–carbon backbones, polyphosphazene, on the other hand, possesses a backbone with alternative phosphorus and nitrogen atoms and two substitutive groups on phosphorus atoms. Polyphosphazenes can be synthesized from precursor macromers poly(dichlorophosphazene) into water soluble polyphosphazene polyacid. The resulting polyacid can then be cross-linked into ionic hydrogels (Figure 5.20) [Andrianov et al., 1998, 2004]. The degradation rate of polyphosphazene has been shown to depend on the degree of substitution of the pendant groups. Specifically, the degradation rate decreases with a decreasing degree of substitution [Andrianov et al., 2004].
Intumescent FRs (IFRs)
Published in Asim Kumar Roy Choudhury, Flame Retardants for Textile Materials, 2020
While polyphosphazene exhibits some level of flame retardancy, its performance is not enough to fulfill the requirements of the FAA for aircraft interiors. In order to make ultra-fire-resistant elastomers, the use of expandable graphite was investigated by Lyon et al. (2003).
Controlled biointerfaces with biomimetic phosphorus-containing polymers
Published in Science and Technology of Advanced Materials, 2021
Suphatra Hiranphinyophat, Yasuhiko Iwasaki
The second category of phosphorus-containing polymers (Figure 1) includes polymers with phosphorus in the main chain. Polyphosphazene is one of the most historical phosphorus-containing polymers and was originally synthesized by Stokes [40,41]. Polyphosphazene is known as inorganic rubber, which is a type of organic-inorganic hybrid high-molecular polymer whose main chain contains alternating single and double bonds of phosphorus and nitrogen and is endowed with excellent flame-retardant synergies. In recent years, polyphosphazene has attracted interest not only in the industrial field but also in the biomedical field, such as matrices for drug delivery [42], tissue engineering [43], and immune adjuvant [44].