The State of the Art in Boron Polymer Chemistry

Abstract

I. INTRODUCTION A. A Brief Historical Perspective on Boron and Its PolymersBoron (Buraq in Arabic/Burah in Persian, which is the word for "white," the color being attributed to borax (sodium tetraborate, Na 2 B 4 O 7 .10H 2 O)) was discovered in 1808 independently by the British Chemist, Sir Humphry Davy, and two French chemists, Joseph Louis Gay-Lussac and Loius Jacques Thenard. 1 They isolated boron in 50% purity by the reduction of boric acid with sodium or magnesium. The Swedish chemist Jons Jakob Berzilius identified boron as an element in 1824. The first pure sample of boron was produced by the American chemist William Weintraub in 1909. Boron does not appear in nature in elemental form, but is found in its compounded

Primary Alkylphosphine–Borane Polymers: Synthesis, Low Glass Transition Temperature, and a Predictive Capability Thereof

“…The vast majority of polymer science comprises materials with carbon-based structures. Polymers based on main group elements are of considerable interest thanks to their wide-ranging chemical, thermal, and mechanical properties. − Much of the research in this field has focused on silicon-based polymers including but not limited to poly­(siloxanes) − and poly­(silanes). , Other more recent areas of interest have included polymers based on elements such as phosphorus, − sulfur, − tin, , and boron. , One interesting class of boron-containing polymers are the poly­(phosphine–borane)­s, [RR′P·BH 2 ] n , which have shown potential use in lithography , and may be useful as pre-ceramic materials . Polymers containing phosphorus or boron have also been shown to be of interest as flame-retardant materials. , …”

“…8,9 Other more recent areas of interest have included polymers based on elements such as phosphorus, 10−12 sulfur, 13−15 tin, 16,17 and boron. 18,19 One interesting class of boron-containing polymers are the poly(phosphine−borane)s, [RR′P•BH 2 ] n , which have shown potential use in lithography 20,21 and may be useful as pre-ceramic materials. 22 Polymers containing phosphorus or boron have also been shown to be of interest as flame-retardant materials.…”

Poly(cyclosiloxane–carborane)s for harsh environments

“…Therefore, boron compounds are usually Lewis acids, which are easy to combine with electron rich substances to make up for their electron deficiency. 9 Based on this principle, the substitution reaction can occur on the C–H and B–H bond of carboranes without destroying the cage structure of carboranes, which provides an effective way for the introduction of carboranes into polymers. In the 1960s, the Olin company found out that o -carborane tends to form cyclic compounds in the polymerization process due to its 1,2-orientation, so it was difficult to form polymers, 10 while m -carborane has little tendency to form a ring structure due to its 1,7-orientation.…”

Alternatives to Thermal Curing in Diacetylene-Containing Carboranylenesiloxanes

“…During the early development of the carboranylenesiloxane chemistry, the available method for the production of a network polymer from a precursor carboranylenesiloxane was by the polymerization in air (at 315°C for 300h) of the vinyl groups of a pendant vinylcontaining carboranylenesiloxane by organic peroxides (2). However, in recent times, research in this area has resulted in the development of extended network systems of carboranylenesiloxanes that were produced either by the thermal polymerization of the diacetylene groups (PCSA networks) (Figure 2) (5) or by the hydrosilation of vinyl or ethynyl groups ( Figure 3) (4). While the hydrosilation reaction proceeded at ambient conditions, the thermal curing required the exposure of the materials to temperatures in excess of 250°C for several hours.…”