Effects of Lithium Bromide on the Glass Transition Temperatures of Linear and Macrocyclic Poly(2-vinylpyridine) and Polystyrene

Synthesis and characterization of macrocyclic poly(.-methylstyrene)

“…At lower DP's the T g values rapidly decrease below a DP of about 40 although the T g 's of the macrocycles are still between 7 and 20ºC higher than those of the corresponding isobaric linear polymers [10].…”

“…We [10], and others [1,11] have shown that, above a degree of polymerization (DP) in excess of about fifty, the glass transition temperatures (T g 's) of macrocyclic PS and poly(2-vinylpyridine) are molecular weight independent and identical to that of high MW PS. At lower DP's the T g values rapidly decrease below a DP of about 40 although the T g 's of the macrocycles are still between 7 and 20ºC higher than those of the corresponding isobaric linear polymers [10].…”

“…The synthesis and properties of macrocyclic polymers, macrocyclic polystyrene (PS) in particular, has been a topic of increased interest in recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Thus the synthesis of macrocyclic PS by cyclization of hetero-bifunctional end functionalized linear precursors has been reported [10][11][12][13][14].…”

“…Thus the synthesis of macrocyclic PS by cyclization of hetero-bifunctional end functionalized linear precursors has been reported [10][11][12][13][14]. We have recently reported that low molecular weight (M n < 5000) macrocyclic PS prepared at -100 ºC by the lithium naphthalide initiated polymerization of styrene and cyclized with 1,4-bis(bromomethyl)benzene (DBX) or dibromomethane (DBM) [10,15] shows an enhanced near UV emission the origin of which is being studied [15,16]. Thus the synthesis and properties of the analogous but sterically more encumbered poly(.-methylstyrene) (PAMS) is of interest.…”

“…Most well defined macrocyclic vinyl polymers have been synthesized via coupling of two-ended living polymer dianion precursors at low anion concentrations with difunctional electrophiles at ambient temperatures [1][2][3][4][5][6][7][8][9][10]. Although the anionic polymerization/cyclization method is rapid and synthetically convenient, one of the main difficulties with this method is the presence of highly reactive dianion polymer precursors that, at least at ambient temperatures, may be partially protonated or otherwise terminated.…”