Molar‐Mass Analysis of Dendrigraft Poly(l‐lysine) (DGL) Polyelectrolytes by SEC‐MALLS: The "Cornerstone" Refractive Index Increment. Issue 1 (15th October 2014)

• Record Type: Journal Article
• Authors: Maret, Barbara; Crépet, Agnès; Faye, Clément; Garrelly, Laurent; Ladavière, Catherine
• Is Part Of: Macromolecular chemistry and physics. Volume 216:Issue 1(2015:Jan.)
• Page Start: 95
• Page End: 105
• Publication Date: 2014-10-15
• Subjects: Polymers -- Periodicals; Polymerization -- Periodicals; Synthetic products -- Periodicals; Macromolecules -- Periodicals; 547.7
• DOI: 10.1002/macp.201400400
• Languages: English
• ISSNs: 1022-1352

Abstract

<abstract abstract-type="main" xml:lang="en"> <title> <x xml:space="preserve">Abstract</x> </title> <p>Dendrigraft poly(<sc>l</sc>‐lysine) (DGL) polyelectrolytes, obtained by iterative polycondensation of <italic>N</italic>‐trifluoroacetyl‐<sc>l</sc>‐lysine‐<italic>N</italic>‐carboxyanhydride, constitute very promising candidates in many biomedical applications. In order to get a better understanding of their structure–property relationships in these applications, their absolute average molecular weights have to be accurately measured. Size‐exclusion chromatography coupled to a multi‐angle laser‐light‐scattering detector (SEC‐MALLS) is known to be the most appropriate analytical tool. These measurements require the determination of the refractive index increment, d<italic>n</italic>/d<italic>c</italic>, of these highly branched polycationic macromolecules in aqueous solution. This optical property has to be measured in the same aqueous conditions as SEC‐MALLS eluents. Consequently, data are determined and discussed as a function of different aqueous SEC‐MALLS eluents, as well as different counter‐ions of the many ammonium groups of DGL (generation 3, DGL‐3, used as a model herein). The resulting number‐average molecular weights, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh30w8zkh8" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:dummy:macp201400400:equation:macp201400400-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mover accent="true"><mml:mi>M</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi mathvariant="normal">n</mml:mi></mml:msub></mml:mrow></mml:math></alternatives></inline-formula>, are found to be very dissimilar when the measured d<italic>n</italic>/d<italic>c</italic> values are directly considered. In contrast, very close <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh30w8zkgq" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:dummy:macp201400400:equation:macp201400400-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mover accent="true"><mml:mi>M</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi mathvariant="normal">n</mml:mi></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> values are obtained (average <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgh30w8zkp1" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="inline" altimg="urn:x-wiley:dummy:macp201400400:equation:macp201400400-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mover accent="true"><mml:mi>M</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi mathvariant="normal">n</mml:mi></mml:msub></mml:mrow></mml:math></alternatives></inline-formula> = 18 700, standard error of 1110 g mol<sup>−1</sup>) with a low coefficient of variation for such data (ca. 6% for six analyses), when the d<italic>n</italic>/d<italic>c</italic> are corrected by the exact lysine amount (measured by the total Kjeldahl nitrogen method). <boxed-text content-type="graphic" position="anchor" orientation="portrait"><graphic position="anchor" mimetype="image" xlink:href="ark:/27927/pgh30w8zcvp" orientation="portrait" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /></boxed-text></p> </abstract>