Luminescence techniques and characterization of the morphology of polymer latices

The pH-responsive behaviour of poly(acrylic acid) in aqueous solution is dependent on molar mass

“…Assuming that this occurs via a simple relaxation mechanism and that the fluorophore is in a homogeneous state, it can be modelled using an exponential decay with time constant t c . 13 Polymers obtained by RAFT are susceptible to fluorescence quenching, 17 but the PAA used here exhibited no luminescence, as determined by steady state measurements (recorded using a Fluoromax-4 spectrofluorometer in ultra-pure water) at these excitation and emission wavelengths, even with the large amounts of chain transfer agent used in the RAFT synthesis.…”

“…RAFT polymerization [11][12][13][14] was used to synthesize a series of poly(acrylic acid) samples with a range in (number average) molar mass from 6.6 to 63.2 kDa. Most of the samples were copolymerized so that approximately 1% of the monomers contained an acenaphthylene (ACE) unit.…”

“…Conformational changes in polymers can be observed using luminescent labelling techniques, by attaching an aromatic label and observing the lifetime and anisotropic response of the excited state. 4,13 Excited state lifetime and time resolved anisotropy measurements (TRAMS) were recorded using an Edinburgh Instruments 199 fluorescence spectrometer at l ex = 295 nm and l em = 350 nm on dilute solutions of PAA, dissolved in ultrapure water at 1 mg ml À1 . The aromatic label (ACE) can be covalently bound to the PAA backbone, giving a direct measure of the polymer segmental motion.…”

Optical Properties of Polyelectrolytes

“…The sensitivity of the fluorescence lifetime (t f ) of a fluorescent label or probe to its environment can often yield important information concerning the conformation of a polyelectrolyte in aqueous solution [12,[19][20][21][22]26,46,60,61,[87][88][89].…”

“…[12,[19][20][21][22]26,46,[60][61][62][87][88][89]). [12,[19][20][21][22]26,46,[60][61][62][87][88][89]).…”