Analytical methods for molecular weight determination of poly(p‐xylylidene dialkyl sulfonium halide): Degree of polymerization of poly(p‐phenylene vinylene) precursors

Red Light Emitting “Push−Pull” Disubstituted Poly(1,4-phenylenevinylenes)

“…While it is not clear that the use of polystyrene standards will give a completely accurate determination of the DPs for 11 and 12 , previous molecular weight determinations of functionalized PPV precursor polymers have been in reasonable agreement with the molecular weights determined by independent light scattering studies. The polydispersities of 11 and 12 are in the 2.0−3.5 range, which is not atypical by comparison to previous investigations of Wessling PPV precursors . The observed DPs are not particularly high by comparison to previous reports, but considerable improvement in DPs can be achieved by rigorous purification of starting materials and fine-tuning of polymerization conditions, albeit at a considerable cost in money and effort .…”

Polyion conformation and second virial coefficient dependences on the ionic strength for flexible polyelectrolyte solutions

“…The solubility in water is found to be drastically affected by counterion excess. A precipitation process takes place in these solutions for high ionic strengths, for instance.14, 15,25,26 The dissolution of PPV precursor derivatives (with tetrafluoroborate side groups, for instance) was also found to be fairly poor.26 These properties suggest a rather "bad" solvent quality for the present methanol. The involvement of phenyl rings within the backbone would tend to stretch the chain locally.…”

“…Early GPC measurements on a rather modified PPV precursor compound (tetrafluoroborate side groups instead of sulfonium salt), dissolved in DMF, provided an estimate for the molecular weight:26 Mw =* 106 Mw/M" =* 2 (13) These values are not extremely accurate though, since GPC applied to polyelectrolyte solutions is often associated with difficulties. 26 For our electrolyte, we used sodium chloride (NaCl) from Fisher. All measurements were done at a given constant temperature (room temperature, T a* 25 °C).…”

Elimination of ion-exchanged precursors to poly(phenylenevinylene)

“…Figure4. Thermal gravimetric analysis of PXT films under a nitrogen atmosphere (heating rate of 10 °C min'1): (-) PXT fluoride; (---) PXT chloride; (--) PXT bromide; (--) PXT acetate.…”