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1615439 
Journal Article 
Thermoreversible crosslinking of polyethylene enabled by free radical initiated functionalization with urethane nitroxyls 
Chaudhary, BI; Peterson, TH; Wasserman, E; Costeux, S; Klier, J; Pasztor, AJ, Jr 
2010 
1 
Polymer
ISSN: 0032-3861 
51 
1 
153-163 
WOS:000273439500020 
This paper describes the functionalization of polyethylene
with urethane derivatives of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO), resulting in
thermoreversible crosslinking of the polymer, which exhibits thermoplastic characteristics at
sufficiently elevated temperatures. The urethane TEMPO adducts were synthesized by the reaction
of 4-hydroxy TEMPO with various diisocyanates using appropriate catalysts, and were subsequently
grafted to polyethylene using free-radical chemistry. A model study conducted on urethane
isopropanol adducts confirmed that endothermic urethane reversion occurred with aromatic and
alkyl diisocyanates at temperatures greater than 170 degrees C, and no exothermic urethane
decomposition was observed. In contrast, urethane TEMPO adducts underwent exothermic
decomposition at elevated temperatures, probably because of participation of the free nitroxyl
species in urethane decomposition. Hence, the urethane TEMPO adducts were most effective when
used as crosslinkers below their decomposition points. (C) 2009 Elsevier Ltd. All rights
reserved. 
Thermoreversible; Crosslinking; Polyethylene