RESEARCH
Polymer Prospects Seen Why bother when
Aromatic fluorocarbons may lead to heat- and radiationstable polymers
you c a n g e t it from Eastman?
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cently a m o n g the neglected compounds of organic chemistry, a r e being studied as starting materials for preparing heat- a n d radiation-stable pol\ mers. I util now, these compounds eoukl he prepared onl\ by tedious, dangerous, and expensive techniques. But now. chemists at the National Bureau of Standards have developed new tech niques a n d modified old ones which ma\ push the compounds into the torefront of polymer chemistrv. • Hexafluorobenzene. The bureau's Walter J. Pummer, Leo A. Wall, and H. E. Florin believe that hexafluorob e n / e n e promises to b e an extremck useful compound since it can be used as a starting material for synthesizing new monomers or compounds having the peifkiorophemi group ( F makes bond stronger; aroinatics are more heat resistant). Earlier syntheses produced hcxafluoroben/ene in only small yields. But t h e \ B S chemists have modified a method developed by Désirant in Belgium. Discovered in 1935 ( b u t not published until 1 9 5 5 ) , the procedure is to pyrolyze tribromofluoromethane at 540° C . in a platinum furnace. T h e \ B S group uses pressures from 5 0 to 265 p.s.i., gets yields better than 5 5 ' , . They get smaller yields (20 to 5 0 ' r ) using furnaces m a d e of borosilicatc glass, graphite, or nickel. P u m m e r and his coworkers get an S()'< yield of pentafluorophenol using hexafluorobenzene and potassium hydroxide in a pyridine medium. They have also reduced hexafluorobenzene with hydrogen. T h e chemists use platinum or palladium mounted on activated charcoal pellets as a catalyst. The yields range from 40 to 60% pentafluorobenzene. • Low Weight Polymers. Though the X B S workers have not yet made any high molecular weight polymers, they have produced low molecular weight polymers that distill out at 350° C. T h e starting material for these polymerizations is sodium pentafluorophenolate. This is thermally decomposed to make t h e polymer.
The NBS chemists h a v e partiallv fluoritiated sty rem» monomer, are n o w fixing to m a k e a completely fluorinated stxrene ring monomer. They're also w orking on the siloxane polymers. They start with t h e pentafluoroniagncsium Grignard. let it react with silicon tetrachloride, a n d get a 3 0 ' ^ yield of tetra-riv-fluorophenylsilane. This c o m p o u n d is used as a precursor for t h e siloxane polymers. • Not b y Choice. P u m m e r says t h a t the aromatic fluorocarbons have b e e n neglected by chemists, not by choice but because of convenience—svn theses were too complicated a n d d a n g e r o u s . L'util recently, he says, it w a s virtually impossible to prepare perfluoroaromatic materials without using these inconvenient methods. Aromatic fluorocarbons, he points out. m a k e u p one of the remaining families of c o m p o u n d s that otter much promise for s y n t h e sizing new t.iermallv stable polvmers.
• National
B u r e a u o f S t a n d a r d s has
developed a photoelectric device t h a t automatically and continously indicates the position of t h e swinging b e a m in a high-precision balance. T h e device is used as a research tool so that scientists can get a better u n d e r s t a n d i n g of balance error. • The Nutrition Foundation has g r a n t e d an additional S 128,000 to 12 universities a n d medical schools for research in the nutritional sciences. Total foundation grants are n o w over $5.2 million. • A missile (the Hare) propelled by energy from o x \ g e n in t h e a t m o s p h e r e is being studied b y Air Force scientists. T h e proposed missile would b e propelled by recombination of ox\ gen atoms on a catalytic surface inside the missile. T h e a t m o s p h e r e would be scooped in, heated, a n d rush out t h e tail, propelling the missile forward. T h e Hare would fly at an altitude of about 59 miles a n d at a speed of a b o u t 1326 feet p e r second. • Vitro Laboratories will study the chemistry of the long-lived radioactive isotopes under a contract from Phillips Petroleum's atomic energy division. Aim of t h e research: t o develop safe and effective storage methods for "hot" fission products.
