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10The 30th International Conference on Advanced Laser Technologies
ALT'23
B-O-6
Raman study of biodegradable poly(L-lactide-co-s-caprolactone)
materials
V.S. Novikov', S.O. Liubimovskii1, E.A. Sagitova1, S.M. Kuznetsov1, N.G. Sedush2, S.N. Chvalun2,
G.Yu. Nikolaeva'
1-Prokhorov General Physics Institute of the Russian Academy of Sciences, Vavilov St. 38, 119991 Moscow, Russia 2- Enikolopov Institute of Synthetic Polymeric Materials of the Russian Academy of Sciences, Profsoyuznaya 70,
117393 Moscow, Russia
Poly(L-lactide) (PLLA) is biocompatible and biodegradable thermoplastic, which has the highest world consumption volume among bioplastics. PLLA has numerous applications, for example, as filament material in 3D printing, in production of ecologically friendly short-life consumer goods, including food wraps and disposable tableware. Also PLLA is widely used in medicine, in particular, as bioresorbable suture materials. PLLA-based copolymers, composites and blends have great potential for novel applications in production of bioresorbable medical implants, scaffolds and nanocarriers for targeted drug delivery with controlled release of active substances. Thus, analysis of the structure and degradation mechanism of various PLLA-based materials is of significant interest. In this work we applied Raman spectroscopy to study copolymers of L-lactide (LA) and s-caprolactone (CL) with the aim to evaluate the relative contents of the comonomers and the degree of crystallinity.
Fig. 1. Raman spectra of semicrystalline (the degree of crystallinity is 86%) and amorphous PLLA in the most informative spectral regions. In each region the intensity of the spectra was normalized to the intensity of the most intense band. The spectra were recorded using Bruker Senterra II Raman microscope with the spectral resolution of 1,5 cm-1 and laser excitation with wavelength of 532 nm.
We showed that the degree of crystallinity of PLLA areas in the LA/CL copolymers can be evaluated from measurements of the ratio of intensities of the PLLA bands at 411 and 874 cm-1 (Fig. 1A). These bands were assigned to the deformation vibrations of O-C(H)-C(H3) groups and the symmetric stretching vibrations of C-O-C bonds on the base of quantum chemical calculations. The range of the C=O stretching vibrations (Fig. 1B) is not convenient to use in the analysis of the LA/CL copolymers because of the strong influence on this region of both copolymer chemical composition and the degree of crystallinity. The relative contents of comonomers in the LA/CL copolymers can be measured using the intensities ratio of the bands at 2947 and 2914 cm-1, related to the symmetric stretching vibrations of CH3 groups of PLLA monomeric units (Fig. 1C) and the symmetric stretching vibrations of CH2 groups of poly(s-caprolactone) monomeric units. Our Raman data on the contents of the comonomers and the degree of crystallinity of the PLLA areas are in good agreement with the results of X-ray diffraction study of these copolymers.
This study was supported by the Russian Science Foundation under the grant № 23-22-00347, https://rscf.ru/en/proj ect/23-22-00347/.
