Molecular weight distribution characterization of hydrophobe-modified hydroxyethyl cellulose by size-exclusion chromatography

• Published in: Journal of Chromatography A Vol. 1359; pp. 182 - 188
• Main Authors: Li, Yongfu, Meunier, David M., Partain, Emmett M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 12.09.2014; Elsevier
• Subjects: Analytical chemistry; Applied sciences; beta-Cyclodextrins - chemistry; Cellulose - analogs & derivatives; Cellulose - chemistry; Cellulose - isolation & purification; Cellulose ethers; Chemistry; Chromatographic methods and physical methods associated with chromatography; Chromatography, Gel - methods; Cyclodextrin; Exact sciences and technology; Hydrophobe modification; Hydrophobic and Hydrophilic Interactions; Inclusion complex; Molecular Weight; Organic polymers; Other chromatographic methods; Physicochemistry of polymers; Properties and characterization; Size-exclusion chromatography; Structure, morphology and analysis; Hydrophobe modification; Cyclodextrin; Size-exclusion chromatography; Inclusion complex; Cellulose ethers; Molecular weight distribution; Hydrophobic compound; Ethylene oxide copolymer; Gel permeation chromatography; β-Cyclodextrin; Chemical modification; Inclusion compound; Cellulose ether; Cellulose(hydroxyethyl)
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2014.07.042

•Successful SEC conditions for HmHEC are reported for the first time.•β-CD was used to eliminate hydrophobic interactions to enable SEC elution.•The developed SEC conditions were robust for HmHEC having MW up to 2000kg/mol.•Comparison of MW obtained by SEC-MALLS, PEO and HEC calibration is reported. Size-exclusion chromatography (SEC) of hydrophobe-modified hydroxyethyl cellulose (HmHEC) is challenging because polymer chains are not isolated in solution due to association of hydrophobic groups and hydrophobic interaction with column packing materials. An approach to neutralize these hydrophobic interactions was developed by adding β-cyclodextrin (β-CD) to the aqueous eluent. SEC mass recovery, especially for the higher molecular weight chains, increased with increasing concentration of β-CD in the eluent. A β-CD concentration of 0.75wt% in the eluent was determined to be optimal for the HmHEC polymers studied. These conditions enabled precise determinations of apparent molecular weight distributions exhibiting less than 2% relative standard deviation in the measured weight-average molecular weight (MW) for five injections on three studied samples and showed no significant differences in MW determined on two different days. The developed technology was shown to be very robust for characterizing HmHEC having MW from 500kg/mol to 2000kg/mol, and it can be potentially applied to other hydrophobe-modified polymers.