Vibrational spectroscopy in the development of surface hydrophilic elastomer latex (SHEL)

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• 作者：Isao Noda ; ^{noda@udel.edu" class="auth_mail}
• 关键词：Vibrational spectroscopy ; Materials development ; Photoacoustic spectroscopy ; Raman process monitoring ; Two-dimensional correlation analysis
• 刊名：Vibrational Spectroscopy
• 出版年：March, 2014
• 年：2014
• 卷：71
• 期：Complete
• 页码：70-75
• 全文大小：980 K

文摘

An illustrative example is given to show how various vibrational spectroscopy techniques coupled with two-dimensional (2D) correlation analysis can be effectively utilized in the development of a novel and functional material. Surface-hydrophilic elastomer latex (SHEL) is a material exhibiting rather unusual permanently water-wettable surface feature despite having a soft and rubbery bulk property, which can be successfully analyzed with vibrational spectroscopy. 2D photoacoustic (PAS) IR spectra of a SHEL film indicate the localized surface segregation of long-chain ethoxylate moiety of the oligomeric surfactant used in the preparation of this material. The accumulation of the hydrophilic long-chain ethoxylate produces the high energy polar surface over the hydrophobic bulk phase of SBR copolymer. The persistence of very low water contact angle, even after repeated washing of a SHEL film with an excess amount of water, indicates permanent covalent attachment of long-chain ethoxylate group to the SBR copolymer. 2D Raman spectra generated from the process monitoring of the emulsion copolymerization of SHEL reveal the mechanism of the covalent attachment of long-chain ethoxylate. The reaction involves a separate step of oleyl moiety of the block surfactant reacting with 1,3-butadiene prior to the onset of copolymerization to produce the SBR latex product.