Temperature-Responsive Lactic Acid-Based Nanoparticles by RAFT-Mediated Polymerization-Induced Self-Assembly in Water

Sarah E Woods; James David Tinkler; Nabil Bensabeh; Marc Palà; Simon J Martin; Ignacio Martin-Fabiani; Gerard Lligadas; Fiona L Hatton

doi:10.1021/acssuschemeng.3c01112

Temperature-Responsive Lactic Acid-Based Nanoparticles by RAFT-Mediated Polymerization-Induced Self-Assembly in Water

ACS Sustain Chem Eng. 2023 Jun 26;11(27):9979-9988. doi: 10.1021/acssuschemeng.3c01112. eCollection 2023 Jul 10.

Authors

Sarah E Woods¹, James David Tinkler¹, Nabil Bensabeh², Marc Palà², Simon J Martin¹, Ignacio Martin-Fabiani¹, Gerard Lligadas², Fiona L Hatton¹

Affiliations

¹ Department of Materials, Loughborough University, Loughborough LE11 3TU, United Kingdom.
² Laboratory of Sustainable Polymers, Department of Analytical Chemistry and Organic Chemistry, University Rovira i Virgili, 43007 Tarragona, Spain.

Abstract

This work demonstrates for the first-time biobased, temperature-responsive diblock copolymer nanoparticles synthesized by reversible addition-fragmentation chain-transfer (RAFT) aqueous emulsion polymerization-induced self-assembly (PISA). Here, monomers derived from green solvents of the lactic acid portfolio, N,N-dimethyl lactamide acrylate (DMLA) and ethyl lactate acrylate (ELA), were used. First, DMLA was polymerized by RAFT aqueous solution polymerization to produce a hydrophilic PDMLA macromolecular chain transfer agent (macro-CTA), which was chain extended with ELA in water to form amphiphilic PDMLA-b-PELA diblock copolymer nanoparticles by RAFT aqueous emulsion polymerization. PDMLA_x homopolymers were synthesized targeting degrees of polymerization, DP_x from 25 to 400, with relatively narrow molecular weight dispersities (Đ < 1.30). The PDMLA₆₄-b-PELA_y diblock copolymers (DP_y = 10-400) achieved dispersities, Đ, between 1.18 and 1.54 with two distinct glass transition temperatures (T_g) identified by differential scanning calorimetry (DSC). T_g(1) (7.4 to 15.7 °C) representative of PELA and T_g(2) (69.1 to 79.7 °C) of PDMLA. Dynamic light scattering (DLS) studies gave particle z-average diameters between 11 and 74 nm (PDI = 0.04 to 0.20). Atomic force microscopy (AFM) showed evidence of spherical particles when dispersions were dried at ∼5 °C and film formation when dried at room temperature. Many of these polymers exhibited a reversible lower critical solution temperature (LCST) in water with a concomitant increase in z-average diameter for the PDMLA-b-PELA diblock copolymer nanoparticles.