Biodegradable Star-Shaped Poly(lactic acid): Synthesis, Characterization and Its Reaction Kinetics

Abstract

Biodegradable four-arm star-shaped poly(lactic acid) (4sPLA) was synthesized from L -Lactic acid ( L -LA) and pentaerythritol (PENTA), and the polymerization kinetics was studied. The effects of reaction time, reaction temperature and molar ratio on the polymerization of 4sPLA were discussed. The molecular structure of 4sPLA was characterized by Fourier transform infrared spectroscopy (FTIR) and 1 H nuclear magnetic resonance spectra ( 1 H-NMR). The results showed that the optimum reaction conditions were as follows: the molar ratio of L -LA to PENTA was 12:1, and the polymerization reaction occurred at 160 ℃ for 5 h. Gel permeation chromatography (GPC) method was used to determine the polymerization kinetics of 4sPLA consistent with the first-order reaction kinetics.

Synthesis of multitask star‐shaped oligoaniline: Introducing a novel, efficient epoxy hardener

“…The 1 H‐NMR spectrum (Figure 3C) has confirmed the structure of the star‐shaped biobased core (S‐PL) (Scheme 1C) and the characteristic peaks are in accordance with the reported studies 54,55 . The feature signals in Figure 3C can be summarized as follows: CH adjacent to the hydroxyl group (CH(OH)) at (5.05–5.13) ppm (marked as 1), methylene protons (CH 2 OCO) at (3.93–4.17) ppm (marked as 2), and the methyl group (CH 3 ) assigned to LA at (1.23–1.46) ppm (marked as 4).…”

“…According to Figure 2C, a biobased star‐shaped core can be characterized as follows: a broad peak at 3420 cm −1 attributed to the hydroxyl end‐terminated (OH) groups (which are available for further coupling steps and esterification reaction), and three absorption bands at 2980, 2940, and 2880 cm −1 which are assigned to the stretching of methyl (CH 3 ), methine (CH) groups of lactic segments, and methylene (CH 2 ) group of PEN, respectively 54,55 . Furthermore, the strong peak at 1745 cm −1 represents the carbonyl group (CO) of the formed ester 56 .…”

“…53 According to Figure 2C, a biobased star-shaped core can be characterized as follows: a broad peak at 3420 cm À1 attributed to the hydroxyl end-terminated ( OH) groups (which are available for further coupling steps and esterification reaction), and three absorption bands at 2980, 2940, and 2880 cm À1 which are assigned to the stretching of methyl ( CH 3 ), methine ( CH) groups of lactic segments, and methylene ( CH 2 ) group of PEN, respectively. 54,55 Furthermore, the strong peak at 1745 cm À1 represents the carbonyl group (C O) of the formed ester. 56 The signals that appeared at 1479 and 1375 cm À1 can be ascribed to the bending absorption of methylene (CH 2 ) and the methyl ( CH 3 ) groups 57 and three bands at 1214, 1126, and 1062 cm À1 ascribed to the stretching vibration of (C O C) groups of ester and hydroxyl moieties (Figure 2C, pink circle).…”

“…The 1 H-NMR spectrum (Figure 3C) has confirmed the structure of the star-shaped biobased core (S-PL) (Scheme 1C) and the characteristic peaks are in accordance with the reported studies. 54,55 The feature It should also be added that in all 1 H-NMR spectra, the peaks at $1.76, 2.09, 3.33, and 3.90 were assigned to the residual THF, acetone, water, and DCE in the samples, respectively, and the peak appeared at 2.54 ppm is attributed to DMSO. 63…”

Molecular structure design and epoxy functional modification of star-shaped poly(lactic acid) by a melt polycondensation strategy

“…[8][9][10][11] Compared with linear PLA, branched PLA has multiple topological structures, such as star-shaped, comb-shaped, long chain branched, hyperbranched, H-shaped, and dumbbell-shaped. [12][13][14][15][16] The branched structures endow PLA with special properties, such as having multiple terminal groups, high melt strength, good rheological properties, and excellent processability. Branched PLA can undergo chain entanglement at lower molecular weight.…”