Design, synthesis, and characterization of a potential flame retardant poly(lactic acid‐co‐pyrimidine‐2,4,5,6‐tetramine) via direct melt polycondensation

Abstract

Directly starting from d,l‐lactic acid (LA) and pyrimidine‐2,4,5,6‐tetramine (PTA), the copolymer P(LA‐co‐PTA) as a novel potential solid compatible polymeric flame retardant is synthesized as designed via melt polycondensation. When the molar feed ratio LA/PTA is 60/1, the optimal synthetic conditions are discussed. After the prepolymerization at 140°C for 8 h, using 0.5 wt % stannous oxide as the catalyst, the melt copolymerization at 160°C for 4 h gives the copolymer with the biggest intrinsic viscosity 0.88 dL g−1. The structures and properties of P(LA‐co‐PTA)s at different molar feed ratios are characterized by FT‐IR, 1H‐NMR, 13C‐NMR, GPC, XRD, DSC, and TGA. The decomposition temperatures of P(LA‐co‐PTA)s are higher than these of homopolymer poly(d,l‐lactic acid) (PDLLA). All copolymers have higher char yield than PDLLA, and the more PTA in the feed content, the higher char yield. What's more, there are some residues at 700–800°C, indicating that P(LA‐co‐PTA)s have good charring ability. When the monomer PTA is introduced into polylactic acid by chemical bonding as purine (PU) unit formed during the condensation, both the PTA's relatively higher nitrogen content and the PU's similar structure with flame retardant benzimidazole are beneficial to improve the thermal stability and charring ability, especially the latter. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40275.

Effect of lactic acid chain length on thermomechanical properties of star‐LA‐xylitol resins and jute reinforced biocomposites

“…FTIR spectroscopy data of the functional groups of the star ‐LA based thermosettings have been previously reported in the literature and were used for assigning the signals in this study. Figure illustrates the FTIR spectra of the step‐one, step‐two and cured samples for resins with different chain lengths.…”

Synthesis and characterization of a novel drug-loaded polymer, poly(lactic acid-co-aminomethyl benzimidazole)

“…[39,40,[45][46][47] Once the molar feed ratio LA/MA is more than or equal to 80/1, the M NMR is obviously smaller than the M T . As reported before, [29,30,[36][37][38][39][45][46][47] this may be related to the fact that some LA molecules can escape out of the reaction systems as the form of lactide during the direct melt copolycondensation. Therefore, only when the proportion of LA in the feed is large enough (e.g.…”

“…After PLAAMB as shown in Scheme 1 is generated, the less LA can make the copolymer each other further etherified by the dehydration between the terminal hydroxyl groups. [39,45,47] In the end, the copolymer as shown in Scheme 2 may be formed.…”

“…[38][39][40] After LA and AMB were uniformly mixed as preplanned molar feed ratio, the mixture was directly dehydrated for 8 h at 140°C under 4000 Pa in a threenecked flask equipped with a mechanical stirring device and a thermometer. After prepolymerization, the selected catalyst was added as predetermined weight percentage of dehydrated reactants (wt%), then the melt copolymerization was carried out at a certain temperature (140-180°C) and an absolute pressure of 70 Pa for 2-10 h. When the reaction is over, the simple purification via the dissolution in CHCl 3 and the subsequent precipitation by CH 3 OH ordinarily produced a white (or yellowish) powder after drying in vacuo to constant weight.…”

“…[28][29][30][31][32][33][34][35][36][37] However, there is no report about the drug delivery of benzimidazole drugs loaded by PLA materials. Herein, on the basis of our previous studies on lactic acid (LA) direct melt polymerization [35,38,39] and benzimidazole compounds, [3][4][5][6] using AMB [10] as a model of benzimidazole-type drugs, poly(lactic acid-coaminomethyl benzimidazole) (PLAAMB) as a potential biodegradable drug-loaded polymer is designed, and synthesized (Scheme 1). After the discussions on the optimal synthetic conditions, the structures and basic properties of PLAAMBs with different molar feed ratios are systematically investigated by Fourier transform infrared (FT-IR), 1 H NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and X-ray diffraction (XRD).…”