Effect of Covalent Intramolecular Crosslinks on Polymer Mechanical Response
Alisa Bouketov
Single chain nanoparticles (SCNPs) are nanoscale architectures formed through intramolecular crosslinking of individual polymer chains, inspired by biomacromolecules.[1] Their compact architecture have attracted significant interest for variety of applications including catalysis[2] and drug delivery.[3] In this work, we studied SCNP systems in solution and in solid state, to understand the role of covalent intramolecular crosslinking on polymer mechanical response.
In solution, we show that mixing linear or SCNPs with complementary hydrogen bonding motifs on their surfaces leads to a significant and differential increase in viscosity.[4] This effect is more pronounced for SCNPs than for linear polymers, indicating that the compact nanoparticle architecture promotes more effective surface to surface interactions. These findings demonstrate that complementary non-covalent interactions can partially compensate for the loss of chain-chain entanglements in compact polymer architecture.
In the solid state, we investigate how intramolecular crosslinking affect mechanochemical stability under ball mill grinding. Using a series of alkyl methacrylate based linear polymers and SCNPs, we demonstrate that polymer degradation rates depend on an interplay between glass transition temperature (Tg) and chain architecture. While increasing side chain length lowers Tg and enhances segmental mobility, intramolecular crosslinking raises Tg and restrict chain mobility, resulting in distinct mechanochemical behavior: SCNPs exhibit accelerated degradation in glassy systems, while showing complete suppression of scission in rubbery system.
Together, these results demonstrate that intramolecular crosslinking governs mechanical response of SCNP based materials in both solution and solid states. These findings establish general design rules and providing a framework for designing advanced functional polymer materials.