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

“…Excited state lifetimes of P(AA-co-ACE) in dilute aqueous solutions typically decrease from 35 to 25 ns as the pH increases, 19 as a result of statistical uncoiling of the polymer backbone. However, as shown in Fig.…”

Poly(acrylic acid) interpolymer complexation: use of a fluorescence time resolved anisotropy as a poly(acrylamide) probe

“…7 In solution alone PAA undergoes a conformational change at low pH, switching from an extended chain to a partially coiled system, and this can be studied by inclusion of a uorescent marker covalently attached along the polymer backbone. 9,10 In this paper we demonstrate how this system can be used as a macromolecular probe to detect IPC formation with PAM via TRAMS, which analyses the rotation of the polymer chain (via the bound uorescent marker) in space. By comparing parallel Fig.…”

Conformational Behavior of a Series of N-Isopropylacrylamide−Bromostyrene Statistical Copolymers via Phosphorescence Measurements

“…(χ 2 should be close to unity for a good fit.) Such behavior is a general feature of stimuli-responsive polymers and is considered to reflect the heterogeneity of local environments extant within the interiors of both the expanded and compact conformations in aqueous media. ,,,,− …”

“…In order to provide a protective environment for the triplet states and generate RTSP, researchers have used guest molecules solubilized in sodium dodecyl sulfate micelles , and methacrylic acid-based polymers ,, in which intersystem crossing (ISC) is enhanced using the external heavy atom effect through replacement of a population of sodium ions by species such as Tl + . In an extension of this theme, the internal heavy atom effect (i.e., an aromatic species containing an intrinsic heavy atom) has been used to promote phosphorescence from probes dispersed in and covalently attached to polyelectrolytes in order to probe the pH-dependent behavior. , If triplet emission can be successfully generated in the current heavy atom modified thermoresponsive polymers, this would provide a novel and unique means of probing the conformational behavior of such materials. Furthermore, invaluable information concerning the “protective nature” of the globular structures created in these systems at temperatures in excess of their respective LCST may be derived.…”

“…Previously, we have modified PNIPAM via simple free radical , and graft copolymerization , to allow control of the conformational switch of the polymer to any desired temperature between 4 and 100 °C. In this paper, as part of an ongoing program, we present results of copolymerization of NIPAM with a comonomer, bromostyrene (BrSTY), and the first observation of phosphorescence in a thermally responsive polymer in aqueous solution: BrSTY was chosen as the chemical modifier, since triplet emission should be stimulated, via the heavy atom effect, in a suitably labeled polymer sample …”