• Palmans, Ara Anja
• Sawamoto, M.
• Artar, Müge
• Ogura, Y.
• Terashima, T.
• Meijer, Ew Bert

Abstract

<p>Chiral 1,3,5-tricarboxamide (BTA)-functionalized copolymers with gradient, bidirectional gradient, and random sequence distributions were synthesized via tandem living radical polymerization (LRP) with in situ monomer transesterification to investigate the effects of the BTA sequence on self-folding/aggregation properties in organic media. Here, 2-ethylhexyl methacrylate (EHMA) as a starting monomer was polymerized with a ruthenium catalytic system in the presence of a chiral BTA-bearing alcohol (BTA-OH) and Ti(Oi-Pr)₄. By tuning the concentration and time of addition of the Ti catalyst, the transesterification rate of EHMA into a chiral BTA-functionalized methacrylate (BTAMA) was synchronized with LRP to produce EHMA/BTAMA gradient or bidirectional gradient copolymers. In contrast, faster transesterification than LRP gave the corresponding random copolymer. Circular dichroism spectroscopy and dynamic light scattering performed on solutions of all BTA-functionalized copolymers indicated that the chiral BTA pendants self-assemble helically via hydrogen-bonding interaction in 1,2-dichloroethane, methylcyclohexane (MCH), and their mixtures to form single-chain or multichain polymeric nanoparticles. The temperature-dependent self-assembly behavior of the BTA pendants was virtually independent of the sequence distribution, whereas the size of the resultant nanoparticles depended on the sequence as follows: random &lt; gradient &lt; bidirectional gradient in MCH.</p>

Topics

• nanoparticle
• Hydrogen
• random
• copolymer
• alcohol
• self-assembly
• dynamic light scattering
• Ruthenium
• random copolymer
• gradient copolymer
• circular dichroism spectroscopy