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Article

On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes

Actinium Chemical Research Institute, Via Casilina 1626a, 00133 Rome, Italy
Int. J. Mol. Sci. 2021, 22(1), 8; https://doi.org/10.3390/ijms22010008
Received: 23 November 2020 / Revised: 16 December 2020 / Accepted: 20 December 2020 / Published: 22 December 2020
(This article belongs to the Special Issue Molecular Nano-Architectures: Chemistry and Physics)
Optical rotatory dispersion (ORD) is a beautiful analytical technique for the study of chiral molecules and polymers. In this study, ORD was applied successfully to follow the degree of polycondensation of l-(+)-lactic acid toward the formation of poly(lactic acid) oligomers (PLAO) and high molecular weight poly(l-lactic acid) (PLLA) in a simple esterification reaction equipment. PLLA is a biodegradable polymer obtainable from renewable raw materials. The racemization of the intrinsically isotactic PLLA through thermal treatment can be easily followed through the use of ORD spectroscopy. Organic or molecular electronics is a hot topic dealing with the combination of π-conjugated organic compounds and polymers with specific properties (e.g., chirality) which can be exploited to construct optoelectronic devices, such as organic light-emitting diodes (OLEDs), organic photovoltaic (OPV) high efficiency cells, switchable chirality devices, organic field-effect transistors (OFETs), and so on. ORD spectroscopy was applied to study either the gigantic optical rotation of PLLA films, as well as to detect successfully the excitonic coupling, occurring in thin solid PLLA green film loaded with a combination of two dyes: SY96 (a pyrazolone dye) and PB16 (the metal-free phthalocyanine pigment). The latter compound PLLA loaded with SY96 and PB16 shows a really gigantic optical activity in addition to typical ORD signal due to exciton coupling and may be considered as a simple and easily accessible model composite of a chiral polymer matrix combined with π-conjugated dyes for molecular electronics studies. View Full-Text
Keywords: poly(l-lactic acid) (PLLA); optical rotatory dispersion (ORD); polycondensation; racemization; thin solid film; exciton coupling; organic electronics poly(l-lactic acid) (PLLA); optical rotatory dispersion (ORD); polycondensation; racemization; thin solid film; exciton coupling; organic electronics
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MDPI and ACS Style

Cataldo, F. On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes. Int. J. Mol. Sci. 2021, 22, 8. https://doi.org/10.3390/ijms22010008

AMA Style

Cataldo F. On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes. International Journal of Molecular Sciences. 2021; 22(1):8. https://doi.org/10.3390/ijms22010008

Chicago/Turabian Style

Cataldo, Franco. 2021. "On the Optical Activity of Poly(l-lactic acid) (PLLA) Oligomers and Polymer: Detection of Multiple Cotton Effect on Thin PLLA Solid Film Loaded with Two Dyes" International Journal of Molecular Sciences 22, no. 1: 8. https://doi.org/10.3390/ijms22010008

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