Control of pH- and temperature-responsive behavior of mPEG-b-PDMAEMA copolymers through polymer composition

ABSTRACT

A series of poly(ethylene glycol) monomethyl ether-block-poly(2-(dimethylamino)ethyl methacrylate) (mPEG-b-PDMAEMA) diblock copolymers were synthesized using atom transfer radical polymerization to achieve controlled polymer molecular weight and narrow molecular weight distribution. The thermoresponsive properties of the mPEG-b-PDMAEMA diblock copolymers in aqueous buffered solutions were determined using UV-Visible spectroscopy and dynamic light scattering. The cloud point, a soluble-to-insoluble transition, was observed for all mPEG-b-PDMAEMA diblock copolymer solutions. Increasing either the mPEG or PDMAEMA molecular weight resulted in a decrease in observed cloud points as a function of pH and polymer concentration. Changing the mPEG molecular weight determined whether a second, higher temperature, thermal transition was observed as a function of pH and polymer concentration. Controlling the thermoresponsive properties of mPEG-b-PDMAEMA diblock copolymers through polymer composition, concentration, and pH enables the tailoring of these copolymers for applications ranging from non-viral gene delivery to use as a strengthening agent in paper.

KEYWORDS:

• Atom transfer radical polymerization
• ATRP
• diblock copolymers
• self-assembly
• stimuli-sensitive polymers

Funding

An acknowledgment is made to the Donors of the American Chemical Society Petroleum Research Fund (Grant #54467-UNI7) for partial support of this research and to the Wisconsin Louis Stokes Alliance for Minority Participation for student support.