Sustainable branched polylactides with N,N-bis(2-hydroxyethyl)glycine as branching units: Intrinsic photoluminescence, guest encapsulation and multifunctional additive for poly(l-lactide) plastics

Multifunctional branched polylactides (BPLAs) with N,N-bis(2-hydroxyethyl)glycine (BHEG) as branching units were prepared. The as-prepared BPLAs had degree of branching in the range of 5.7–9.1%, number-average molecular weight in the range of 7.4 kDa–9.3 kDa, and dispersity in the range of 1.3–1.7. The tertiary amine groups of BHEG units endowed BPLAs intrinsic photoluminescence (PL) nature with quantum yield (QY) in the range of 1.2–2.0% under the maximum excitation wavelength of 360–370 nm and the maximum emission wavelength of 439–445 nm. Oxidized BPLAs showed the maximum excitation wavelength of ca. 473 nm as well as the maximum emission wavelength of ca. 540 nm, and much higher QYs of 9.1–10.5%. The tertiary amine groups of BHEG units also endowed BPLAs guest-encapsulation capacity. The obtained BPLAs were effective multifunctional additives for poly(l-lactide) plastics, embodied with improved crystallization and mechanical properties, PL property and new functions through hosting functional guest molecules.