The titration of polymeric acids

Arnold, Richard T.

doi:10.1016/0095-8522(57)90060-0

Cited by 117 publications

(107 citation statements)

References 9 publications

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“…It was realized only much later that the behavior of PMA is anomalous. Whereas the pK of PAA rises monotonously with increasing ionization, the pK of PMA passes, after an initial rise, through a plateau before resuming its increase (18). Mandel et al interpreted this behavior as reflecting a local conformation transition from a more contracted, less ionized to a more expanded, more highly ionized sequence with the same linear charge density (19).…”

Section: Ionization Equilibriamentioning

confidence: 99%

Polyelectrolyte Solutions: Phenomena and Interpretation

Morawetz¹

2006

ACS Symposium Series

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Section: Ionization Equilibriamentioning

confidence: 99%

Polyelectrolyte Solutions: Phenomena and Interpretation

Morawetz¹

2006

ACS Symposium Series

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“…5 Also, the pK remains constant over a range of pH after an initial increase before resuming its rise with further increase in pH. 6 This has been interpreted 7 as indicating that within the pH range of the pK plateau there is a gradual transition from one to another local conformation with no significant change in the overall expansion of the polyion. Only when this transition is complete does the long-range Coulombic repulsion between the ionic charges with increasing pH lead to the large expansion of the PMA.…”

Section: Introductionmentioning

confidence: 99%

Chemically Induced Dynamic Electron Polarization Studies of a pH-Dependent Free Radical Cage Formed in a Photoinitiator Labeled Poly(methacrylic acid)

Maliakal¹,

Weber²,

Turro³

et al. 2002

Macromolecules

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Time-resolved electron spin resonance (TR-ESR) has been used to investigate the effect of pH-dependent poly(methacrylic acid) clustering on the radical pair generated from photolysis of a poly(methacrylic acid) acid sample randomly labeled with the common R-hydroxy ketone photoinitiator 1. The TR-ESR spectra for the ketyl radical show a dramatic change in electron spin polarization mechanism, from a predominantly triplet mechanism (TM) at low pH (below 6) to a predominantly radical pair mechanism (RPM) at high pH (above 7). The ratio of RPM/TM polarization exhibits a sigmoidal behavior as a function of pH which passes through an inflection point at pH 6.9 ( 0.1. The inflection point agrees well with previous estimates for pH-dependent cluster opening in poly(methacrylic acid). These results indicate that the pH-dependent cluster is capable of forming a cage around the geminate radical pair which restricts its motion at low pH. At higher pH, the cluster opens, allowing the ketyl radical to escape the pair. Studies of the benzoyl partner in the radical pair, which is attached covalently to the polymer backbone, indicate differing environments within the cluster even at pH below cluster opening. This study represents the first application of TR-ESR and electron spin polarization (ESP) to the problem of pH-dependent clustering and reveals new features of the pH-dependent poly(methacrylic acid) cluster.

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“…Where's that, Sir?" Arnold's interest in polyelectrolytes (Arnold, 1957) and ion-exchangers (Hanley et al, 1967) led to papers in collaboration with research students Churms, Ticktin and Monseair. Hotz, a well-liked lecturer and research worker from 1958 to 1963, left for Ottawa (Hotz & Spong, 1962;Brookes et al, 1971).…”

Section: Appointments and Activities In The 1960s; The New Building mentioning

confidence: 99%

A history of the Chemistry Department, University of Cape Town

Stephen¹

2005

Transactions of the Royal Society of South Africa

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includes material from its inception in 1876 until the closing years of the millennium preceding 1999. Several phases of growth are presented: first, as a one-man enterprise, Professor Paul Daniel Hahn introduced the teaching of Chemistry and fostered both pure and applied research; this developed with the founding of the University of Cape Town at the end of World War 1. A move into the new building at Groote Schuur followed, with a rapid expansion on many fronts after World War II. Apart from a brief interlude as a School comprising four separate Departments (1974)(1975)(1976)(1977)(1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988), the Department of Chemistry continued to grow in terms of student numbers, courses offered, and productivity of its research groups, until the present time. The Department has occupied a large building, named after its first full-time professor, since 1972. Advances in performance, consequent on improved, computerised instrumentation and teaching techniques, are evident.

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The titration of polymeric acids

Cited by 117 publications

References 9 publications

Polyelectrolyte Solutions: Phenomena and Interpretation

Polyelectrolyte Solutions: Phenomena and Interpretation

Chemically Induced Dynamic Electron Polarization Studies of a pH-Dependent Free Radical Cage Formed in a Photoinitiator Labeled Poly(methacrylic acid)

A history of the Chemistry Department, University of Cape Town

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