Synthesis and thermal and spectroscopic properties of macrocyclic vinyl aromatic polymers

Abstract

Well-defined and narrow molecular weight distribution macrocyclic poly(2vinylnaphthalene) (P2VN) and poly(2-vinyl-9,9-dimethylfluorene) (PDMVF) containing a single 1,4-benzylidene or 9,10-anthracenylidene unit have been synthesized via the potassium naphthalide initiated polymerization of the monomers followed by the endto-end coupling of the resulting P2VN dianions under high-dilution conditions with 1,4-bis(bromomethyl)benzene or 9,10-bis(chloromethyl)anthracene. Molecular characterization has been carried out by size exclusion chromatography, nuclear magnetic resonance, differential scanning calorimetry, ultraviolet-visible spectroscopy, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The thermal properties show distinct differences between the cyclic and matching linear polymers, with the macrocycles showing much higher glass-transition and decomposition temperatures. The absorption bands are both hyperchromic and hypochromic with respect to the model aromatic compounds, and this is consistent with intensity borrowing.

Cyclic polymers: Synthetic strategies and physical properties

“…[64][65][66] Thermogravimetric measurements conducted in an atmosphere of helium revealed for poly(2-vinyl pyridine), poly(2-vinyl naphthalene), and poly(9,9-dimethyl-2-vinyl fluorine) the same trend. In all cases, the cyclic polymers were slightly more thermostable than the linear analogues.…”

“…This combination of properties allowed for a separation of the quasi monomeric cycles (containing one PS chain) from the higher cyclic or linear polycondensation products by means of size-exclusion chromatography (SEC). [10][11][12][13][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] The optimum iMC was calculated via eq 5, 13 which correlates the molecular weight of the bifunctional polymer chains with a concentration (C eq ) where rates of cyclization and chain growth are equal C eq ¼ a ¼ 1 in eq 3. For bisanionic PS of M n 10 kDa a C eq value around 10 À3 mol/L was calculated.…”

“…[62][63][64][65][66][67][68][69][70] The formulas of these monomers are summarized in Scheme 14. However, in all cases, living anionic polymerizations were used to control the molecular weight and to keep the polydispersities low.…”

“…The bulk of cyclic polymers studied by numerous research groups [57][58][59][62][63][64][65][66]73,74,89,95,253, comprised glass transition temperatures (T g s), melting temperatures (T m s), morphologies, melt viscosities, thermostabilities, and compatibilities. Cyclic PS, cyclic PEOs, and cyclic polysiloxanes were again the most widely studied cyclic polymers.…”

Experimental techniques in high‐vacuum anionic polymerization

“…8 In a similar manner, macrocyclic vinyl aromatic polymers [viz., both poly(2-vinylnaphthalene) and poly(2-vinyl-9,9-dimethylfluorene)] were prepared with the same strategy. 9 Pitsikalis and coworkers synthesized block copolymers of styrene and either stearyl methacrylate 10 or decyl methacrylate. 11 Vazaios and coworkers 12 prepared triblock copolymers and pentablock terpolymers of nhexyl isocyanate with styrene and/or isoprene.…”