*4.3. PLA*/γ*-Cyclodextrins*

A poly(lactic acid) and γ-cyclodextrin inclusion complex was obtained by ultrasonic co-precipitation and used as a precursor for the preparation of its benzyl-hydrazide derivative that was subsequently applied as a nucleating agen<sup>t</sup> for PLA composites [123]. PLA chains penetrated into the cavity of the γ-CD cone, which resulted in a tunnel-shaped crystalline structure. For PLA/γ-CD IC, two prominent X-ray di ffraction peaks were formed (2θ = 7.5◦ and 19.6◦). The latter indicated the channel-like structure characteristic of crystalline necklace-like IC with a fingerprint di ffraction feature at 2θ = 7.5◦. The comparative FTIR analysis of PLA-IC and neat PLA and γ-CD showed that the interactions between those two components were strong. The peak corresponding to symmetric and antisymmetric O-H stretching modes of γ-CD (3405 cm<sup>−</sup>1) was shifted to 3415 cm<sup>−</sup><sup>1</sup> in PLA-IC. This confirmed a non-covalent nature of the interactions between the γ-CD and PLA backbones in the inclusion complex. Moreover, the carbonyl stretching (<sup>ν</sup>, C=O) appeared at 1760 cm<sup>−</sup><sup>1</sup> in the neat PLA and at 1768 cm<sup>−</sup><sup>1</sup> in the IC (noticeably weakened). Calorimetric studies of PLA/PLA-IC showed that Tc and T m trended towards lower-temperature regions. It suggested that PLA-IC could form hydrogen bonds with PLA and break the intermolecular interactions in PLA. PLA/γ-CD IC was also modified via surface-initiated atom transfer radical polymerization to obtain poly(lactic acid)-γ-cyclodextrin inclusion complex-poly(glycidyl methacrylate) (PLA-IC-PGMA) [124].
