Polyurethane nanocomposites containing the chemically active inorganic Sn-POSS cages

• Published in: Reactive & functional polymers Vol. 143; p. 104338
• Main Authors: Strachota, Beata, Strachota, Adam, Horodecka, Sabina, Steinhart, Miloš, Kovářová, Jana, Pavlova, Ewa, Ribot, François
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01-10-2019; Elsevier BV; Elsevier
• Subjects: Cages; Chemical Sciences; Chemical synthesis; Crosslinking; Elastomers; Homology; Hydrogen bonding; Hydrogen bonds; Hydrogen embrittlement; Nanocomposite; Nanocomposites; NMR; Nuclear magnetic resonance; Organic chemistry; Organic-inorganic hybrid; Oxidation; Polymers; Polyurethane; Polyurethane resins; POSS; Properties (attributes); Stannoxane; Tin; POSS; Organic-inorganic hybrid; Nanocomposite; Stannoxane; Polyurethane
• ISSN: 1381-5148; 1873-166X
• DOI: 10.1016/j.reactfunctpolym.2019.104338

Nanocomposite polyurethane (PUR) elastomers were synthesized, which contained the heavier, tin-based homologues of POSS (“Sn-POSS”). Most remarkable was the tremendous effect of extremely small Sn-POSS concentrations (around 0.05 wt%) on the glass transition (up-shift by 30–60 °C) of the oxidized Sn-POSS/PUR hybrids, which offers the possibility of improving the properties of an important engineering material class (PUR). Important in this context is the hydrogen bonding between the polar segments of Sn-POSS and the carbamate groups of PUR, which was elucidated by NMR. The rigid Sn-POSS cages are of interest due to their specific aggregation behaviour (observed above 5 wt%), and particularly due to their chemical reactivity, which counteracts oxidative degradation of the nanocomposites. This chemical effect of Sn-POSS is strong already at 0.01 wt%. At 0.5 wt%, the properties of the oxidized samples stay close to their initial state before the oxidation. On the other hand, at ‘high’ Sn-POSS loadings (5–25 wt%), oxidative crosslinking of Sn-POSS with matrix becomes excessive and the oxidized samples are brittle, while also specific heat-induced carbamate–Sn-POSS reactions deteriorate the properties of such oxidized nanocomposites.