*Review* **Supramolecular Interactions in Hybrid Polylactide Blends—The Structures, Mechanisms and Properties**

## **Anna Kowalewska \* and Maria Nowacka**

Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łód ´z, Poland; mnowacka@cbmm.lodz.pl

**\*** Correspondence: anko@cbmm.lodz.pl; Tel.: +48-42-680-3350

Academic Editor: Sylvain Caillol Received: 19 June 2020; Accepted: 20 July 2020; Published: 23 July 2020

**Abstract:** The conformation of polylactide (PLA) chains can be adjusted by supramolecular interactions (the formation of hydrogen bonds or host-guest complexes) with appropriate organic molecules. The structures formed due to those intermolecular interactions may act as crystal nuclei in the PLA matrix ("soft templating"). In this review, the properties of several supramolecular nucleating systems based on synthetic organic nucleators (arylamides, hydrazides, and 1,3:2,4-dibenzylidene-d-sorbitol) are compared to those achieved with biobased nucleating agents (orotic acid, humic acids, fulvic acids, nanocellulose, and cyclodextrins) that can also improve the mechanical properties of PLA. The PLA nanocomposites containing both types of nucleating agents/additives are discussed and evaluated in the context of their biomedical applicability.

**Keywords:** polylactide; composites; supramolecular interactions; crystallization
