Multistimuli-Responsive Emulsifiers Based on Two-Way Amphiphilic Diblock Polymers

Yeong-Tarng Shieh; Yao-Chuan Yeh; Chih-Chia Cheng

doi:10.1021/acsomega.9b01728

Multistimuli-Responsive Emulsifiers Based on Two-Way Amphiphilic Diblock Polymers

ACS Omega. 2019 Sep 12;4(13):15479-15487. doi: 10.1021/acsomega.9b01728. eCollection 2019 Sep 24.

Authors

Yeong-Tarng Shieh¹, Yao-Chuan Yeh¹, Chih-Chia Cheng²

Affiliations

¹ Department of Chemical and Materials Engineering, National University of Kaohsiung, No. 700, Kaohsiung University Road, Nanzih District, Kaohsiung 81148, Taiwan.
² Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Da'an District, Taipei 10607, Taiwan.

Abstract

Diblock copolymers of poly(tert-butyl methacrylate) (PtBuMA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) of four different block lengths were prepared by sequential two-step reversible addition-fragmentation chain transfer radical polymerization, followed by hydrolysis of the PtBuMA blocks to obtain poly(methacrylic acid)-b-PDMAEMA (PMAA-b-PDMAEMA). The effect of the PDMAEMA block length on the multistimuli-responsive amphiphilic features of both types of diblock copolymers was investigated as CO₂-switchable emulsifiers for emulsification/demulsification of n-octane (an oil) in water in response to CO₂/N₂ bubbling. The amphiphilicity of PtBuMA-b-PDMAEMA was switched on, and the amphiphilicity of PMAA-b-PDMAEMA was switched off by CO₂ bubbling at pH 12 and 25 °C to achieve emulsification/demulsification. A longer PDMAEMA block length in PMAA-b-PDMAEMA conferred more sensitive CO₂-responsive amphiphilicity but reduced the extent of recovery of emulsification ability on N₂ bubbling. This newly developed diblock copolymer system could potentially serve as a "multifunctional surfactant" for CO₂-switchable emulsification/demulsification of oil-in-water and water-in-oil mixtures.