Synthesis and thermal properties of macrocyclic poly(2-vinylnaphthalene) containing single 1,4-benzylidene or 9,10-anthracenylidene groups

The first synthesis of well-defined narrow molecular weight (MW) distribution macrocyclic poly(2-vinylnaphthalene) (P2VN) containing a single 1,4-benzylidene or 9,10-anthracenylidene unit is reported. The synthesis involves the potassium naphthalide (K-Naph) or potassium 1,1,4,4,7,7,10,10-octamethyl-1,2,3,4,7,8,9,10-octahydronaphthacene (K-OMOHN) initiated polymerization of 2-vinylnaphthalene (2VN) in THF at -78 degreesC, followed by end-to-end coupling of the resulting P2VN dianions under high dilution conditions (10(-6)-10(-4) M). Narrow MW distribution (1.11-1.26) P2VN macrocycles with MW's between 740 and 13 200 have hydrodynamic volumes that are between 5% and 29% smaller than those of the matching linear chains. The glass transition temperatures of macrocyclic P2VN do not deviate from the limiting value (151 degreesC) of the high MW P2VN, decreasing only below a DPn of about 20. Compared to the linear analogues, macrocyclic P2VN shows higher nonoxidative thermal decomposition stability.