Radical entry mechanisms in redox-initiated emulsion polymerizations

Lamb, David; Fellows, Christopher M.; Gilbert, Robert G.

doi:10.1016/j.polymer.2005.06.078

Cited by 32 publications

(20 citation statements)

References 52 publications

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“…This decreases the radical mobility and termination rate which leads to an acceleration of the reaction and to higher polymer molecular weights. $ \bar n $ comes back to zero when the reaction stops, that is, when the conversion does not increase any more (even if it is lower than 100%) 57, 58. Note that $ \bar n $ is estimated from the reaction rate (see Supporting Information) and is not modeled as a function of radical entry, desorption, and termination.…”

Section: Resultsmentioning

confidence: 99%

Native American breast cancer survivors' physical conditions and quality of life

Burhansstipanov¹,

Krebs²,

Seals³

et al. 2010

Cancer

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BACKGROUND:Based on Survivors' Guidance, an interactive, Web‐based, culturally relevant Native American cancer survivorship program, Native American Cancer Education for Survivors (NACES), was developed. The focus of the program is to improve quality of life (QOL) for Native American breast cancer survivors.METHODS:NACES is a community‐driven research and education project, based on the Social Cognitive Theoretical Model. Participants complete a QOL survey that includes physical, psychosocial, spiritual, and social components. This publication focuses on the physical component of the survey collected by trained Native American patient advocates, and compares physical conditions among Native American breast cancer survivors who were diagnosed within 1 year, those diagnosed between 1 and 4 years, and those who are long‐term survivors (diagnosed ≥5 years ago).RESULTS:For the first time, survivorship issues are reported specifically for Native American breast cancer patients (n = 266). Selected access issues document situations that contribute to disparities. Comorbidities such as high blood pressure and arthritis are common in the survivors, with more than a third having diabetes, in addition to breast cancer. Numerous side effects from cancer treatments are experienced by these survivors.CONCLUSIONS:These data describe what Native American breast cancer patients are experiencing based on self‐reported information. Clearly there is need for much more work and long‐term tracking of Native American patients to begin to document if or how the severity of physical symptoms lessens over time and if their experiences are significantly different from non‐Native Americans. Cancer 2010. © 2010 American Cancer Society.

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Section: Resultsmentioning

confidence: 99%

Native American breast cancer survivors' physical conditions and quality of life

Burhansstipanov¹,

Krebs²,

Seals³

et al. 2010

Cancer

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“…Thus, radicals are generated in the aqueous phase, and a crucially important aspect of the process is the passage of these radicals into the particles, which is where polymerization occurs [105]. In another study, Lamb et al tackled the topic of radical entry mechanisms in redox-initiated EP [108]. In many ways these investigations could be classified as ones into initiation, but it seems prudent to give EP its own section rather than to include these works in Section 10.3.…”

Section: Emulsion Polymerizationmentioning

confidence: 99%

Elucidation of Reaction Mechanisms: Conventional Radical Polymerization

Buback

Russell

Vana

2011

Mass Spectrometry in Polymer Chemistry

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It is often remarked that the molar mass distribution (MMD) of a polymer contains the entire history of its synthesis. It is because of this truism that those interested in the kinetics of polymerization are driven to understand polymer MMDs. As will be seen in this chapter, in the case of (conventional) radical polymerization (RP), this quest has been enormously advanced by the advent of large-molecule mass spectrometry (MS), for it is a characterization technique that furnishes hitherto unimaginable detail about the MMD of a polymer, and thus it may be used to elucidate or confirm the mechanisms of RP in many ways that simply were not previously possible.What is it that is so special about an MMD yielded by MS? It is not the distribution amount, for size exclusion chromatography (SEC) already makes a superior fist of measuring that, mostly through the use of refractive-index (RI) detection. Admittedly there can be issues with this, for example, that RI is molar mass dependent for oligomers [1]. However, such issues apply only in particular circumstances, and they pale beside the general uncertainty one must attach to polymer amounts as returned via MS: there is no doubt that SEC is a vastly superior technique in this respect. Rather, what is so special about MS is its delivery of the MMD variable, namely molar mass, M. The two important aspects here are mass accuracy and mass resolving powerFor many large-molecule studies, it is the mass accuracy of MS that is revolutionary. Indeed, the knee-jerk reaction of most RP workers would be that this is also the case in their field. In fact, the matter is not so straightforward. A good illustrative example of this is the pulsed-laser polymerization (PLP) method for measuring propagation rate coefficients, k p [3, 4], which requires knowledge of absolute values of M. By now an enormous quantity of accurate k p data has been yielded by this method, almost all of it through the use of SEC [5,6]. This evidences that for the study of RP kinetics and mechanisms, accurate SEC calibration is commonly possible, either directly through the use of standards, or indirectly through the additional use of Mark-Houwink parameters (so-called universal calibration). So, it is not this aspect alone that makes MS so useful.In fact what is so groundbreaking about MS for the study of RP mechanisms is its mass resolving power, that is, the ability of mass analyzers to separate and measure small differences in M, by now to well under 1-Dalton level with most instruments. As Barner-Kowollik et al. expressed it, this gives the power to visualize the individual polymer chains present in a given sample [7]. Thus, for example, polymer chains of identical degree of polymerization but with a different end group can be resolved, something of which SEC will never (in general) be capable. Because of the accurate determination of the M of the resolved species, their precise chemical composition may be deduced, and from this the mechanism of polymer formation can be inferred. Numerous examples of this ge...

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“…One such complicated reaction system investigated in the authors' lab is the free radical redox emulsion polymerization of methyl acrylate (MA). (76,77) The monomer was dissolved in water at approximately 1-10 wt% concentration and a redox couple composed of t-butyl hydroperoxide (tBHP) and sodium metabisulfite (SMBS) was used to initiate the polymerization (Figure 19). It was found that the property of the final poly(methyl acrylate) (PMA) latex products could be significantly affected by the reaction conditions used even if exactly the same concentrations of MA, tBHP, and SMBS were used.…”

Section: Free Radical Emulsion Polymerization Of Methyl Acrylatementioning

confidence: 99%

Raman Spectroscopy of Polymers

Paradkar

Leugers

Patel

et al. 2009

Encyclopedia of Analytical Chemistry

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Raman spectroscopy is a vibrational spectroscopic technique that can provide detailed information about reaction chemistry, structure, chemical composition, and morphology of the chemical species under investigation. Owing to its ease of sampling, Raman spectroscopy is particularly well suited for in situ monitoring and to study polymers and solid samples that are less amenable to other analytical techniques. Polymer powers, pellets, molded articles, fibers, and films can be probed by simply illuminating them with a laser beam and analyzing the backscattered radiation. The primary goal of this article is to provide potential Raman practitioners a high level overview of the technique and instrumentation and different types of polymer‐related applications using some real‐world examples. These applications will generally take advantage of the sampling ease or unique structural information available from Raman spectroscopy. It is not our intention to discuss the theory or present an exhaustive review of the existing Raman literature in any detail. Instead a comprehensive list of references is provided for readers interested in acquiring additional information on specific topics.

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Radical entry mechanisms in redox-initiated emulsion polymerizations

Cited by 32 publications

References 52 publications

Native American breast cancer survivors' physical conditions and quality of life

Native American breast cancer survivors' physical conditions and quality of life

Elucidation of Reaction Mechanisms: Conventional Radical Polymerization

Raman Spectroscopy of Polymers

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