Single Chain Characterization of Hydrophobically Modified Polyelectrolytes Using Cyclodextrin/Hydrophobe Complexes

Abstract

The characterization of hydrophobically modified alkali-soluble emulsions (HASE) using conventional techniques such as gel permeation chromatography or static light scattering is difficult because of the hydrophobic association. Two different approaches were taken to prevent the hydrophobic association of HASE polymers in aqueous solution: (1) hydrolyze the polymer to dislodge the hydrophobic constituents, and (2) use methyl-β-cyclodextrin, which has a hydrophobic cavity and a hydrophilic outer shell, to shield the hydrophobes from associating. Using these two approaches, the molecular weight (M w), hydrodynamic radius (Rh), and radius of gyration (Rg) of single chains of these polymers were determined using gel permeation chromatography (GPC) and dynamic (DLS) and static (SLS) light scattering techniques. The molecular weight of the control polymer (i.e., polymers with similar composition but with no hydrophobe) is found to be ∼7.0 × 10 5 g/mol. The molecular weights of these polymers with C8, C16, and C20 hydrophobes were found to be ∼2.0 × 10 5 g/mol. By comparing GPC and SLS results, we were able to determine that, except for one chemical site, branching or grafting did not occur in the polymer chain during synthesis.

Relaxation Spectra and Viscoelastic Behavior of a Model Hydrophobically Modified Alkali-Soluble Emulsion (HASE) Polymer in Salt/SDS Solutions

“…Synthesis procedure and GPC output of the macromonomer can be found elsewhere (13,25). For RDJ31-5, the molecular weight as determined by static light scattering is ∼180,000 (27). The result agrees with that determined from intrinsic viscosity for the polymers in 0.01 and 0.1 M NaCl solution, where the molecular weight was estimated to be in the range of 170,000 to 190,000 Da.…”

Aqueous solutions of HEC and hmHEC: effects of molecular mass versus hydrophobic associations on hydrodynamic and thermodynamic parameters

“…Aqueous size exclusion chromatography could not be used for hmHEC as a result of supramolecular aggregation (Islam et al 2000). The molecular mass according to literature (Gonzalez et al 2005) is M W = 3.0 9 10 5 Da, with MS = 2.5 ethylene oxide groups per sugar unit, while hydrophobic pendant groups have been reported as hexadecyl chains with approximately 0.01 molar substitution (Gonzalez et al 2005).…”

Rheological properties of hydrophobically modified polyelectrolyte systems: Concentration effects

“…It has an average molecular weight of $ 200,000-250,000 determined by intrinsic viscosity 8 and static light scattering measurements. 23,24 The polymer examined is designated as HASE05-20, and HASE15-20, where the ethylene-oxide spacer chain length of HASE15-20 is 15 mol while HASE05-20 is 5 mol. The hydrophobes of the polymers consist of the C 20 H 41 alkyl chain.…”

“…Although the distribution of the molecular weights of the model associative polymer remains unknown, the molecular weight and monomer sequence distribution of these polymers are believed to be quite similar, since the process used to produce them was held constant. 23 Recently, Sprong et al synthesized HASE polymers with well-controlled molar masses and narrow molar mass distributions using the reversible additionfragmentation chain transfer polymerization of methyl methacrylate, and methacrylic acid. Molecular weights ranging from 27,000 to 50,000 g/mol with polydispersity index of 1.2-1.5 were reported.…”