Limits to expanding the PN‐F series of polyphosphazene elastomers

Abstract

Mixed‐substituent fluoroalkoxyphosphazene polymers bearing ∼15% 1H,1H,2H,2H‐perfluorooctan‐1‐oxy or 1H,1H,2H,2H‐perfluorodecan‐1‐oxy side groups together with trifluoroethoxy cosubstituent groups were synthesized. The low reactivity of the long‐chain fluoroalkoxides and their limited solubility in organic solvents prevented higher levels of substitution. Moreover, the sodium alkoxides with two methylene residues adjacent to the oxygen proved to be unstable in solution due to elimination of NaF and precipitation of side products, and this limited the time available for chlorine replacement reactions. The resulting cosubstituent polymers were characterized by proton nuclear magnetic resonance (1H‐NMR), 31P‐NMR, 19F‐NMR, gel‐permeation chromatography, and differential scanning calorimetry. Unlike homo‐ or mixed‐substituent fluoroalkoxyphosphazene polymers, such as [NP(OCH2CF3)2]n (a microcrystalline thermoplastic, Tg ∼ −63°C, Tm ∼ 242°C) or [NP(OCH2CF3)(OCH2(CF2)xCF2H)]n (PN‐F, a rubbery elastomer, Tg ∼ −60°C, but no detectable Tm), the new polymers are gums (Tg ∼ −50°C, but no detectable Tm) with molecular weights in the 105 g/mol rather than the 106 g/mol range. POLYM. ENG. SCI., 54:1827–1832, 2014. © 2013 Society of Plastics Engineers

Phosphazene High Polymers and Models with Cyclic Aliphatic Side Groups: New Structure–Property Relationships

“…Moreover, the original sharp crystalline-to-mesophase transition at 80 °C in 16 was absent for all the mixed-substituent polymers due to the decrease in macromolecular symmetry caused by the random disposition of different side groups. Such behavior is consistent with those of other reported mixed substituent poly­(organo­phosphazenes). …”

“…Such behavior is consistent with those of other reported mixed substituent poly(organophosphazenes). 28 Thermal Decomposition Temperatures. Thermogravimetric analysis data are unreliable indicators of the mechanism of thermal breakdown of most polymers.…”

An Unusual Polymer Architecture for the Generation of Elastomeric Properties in Fluorinated Polyphosphazenes

“…If only one type of fluorinated side group is present, the polymers are microcrystalline thermoplastics (Chart , structure 1 ), but the presence of two different fluoroalkoxy groups in roughly equal amounts lowers the symmetry, eliminates the crystallinity, and allows low- T g elastomeric properties to emerge. The best-known example of this class is “PN-F” or “Eypel-F” (Chart , structure 2 ), an elastomer developed originally for use in challenging automotive and aerospace environments but also studied for cardiovascular applications and commercialized as a dental material. − …”

Dynamic Polyphosphazene Networks with Modulating Shape Memory and Self‐Healing Capacity by Double Coordination Interactions

“…Polyphosphazene is a unique class of hybrid polymers with an amazing structural design. [ 1,2 ] It has a wide range of applications in high‐performance elastomers such as low‐temperature elastomers, [ 3–5 ] flame‐retardant materials, [ 6–8 ] stretchable electronics, [ 9,10 ] bionic muscles, [ 11,12 ] super‐hydrophobic materials, [ 13,14 ] and biodegradable materials. [ 15–17 ] However, there are few reports about recyclable and self‐healing polyphosphazene, while similar studies are popular in polysiloxane.…”