Novel Periodic Copolymers Consisting of Ester and Amide Units with the Same Carbon Numbers:  Effects of Comonomeric and Sequential Structures on Crystalline Structures and Physical Properties

Abstract

Four novel series of periodic copolymers composed of ester and amide units with the same carbon numbers were synthesized by two-step polycondensation reactions using adipate, linear aliphatic diols, and diamines with various chain lengths, ranging from 3 to 6 methylene groups. Effects of the comonomeric and sequential structures on the physical properties and crystalline structures were investigated for the obtained copolymer series by means of differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and tensile testing. The thermal properties of obtained periodic copolymer series were found to be strongly dependent on both comonomeric and sequential structures, and the values showed remarkable differences between neighboring methylene numbers in the comonomer units. Such thermal behavior was strongly correlated to the wide-angle X-ray diffraction patterns, with some copolymers displaying patterns similar to homopolyesters, while other copolymers had diffraction patterns that were very different than the homopolyester, dependent on the comonomeric and sequential structures. These results suggest that the molecular chain arrangements and their intermolecular hydrogen bond interactions based on the ester-amide sequential structure play an important role in the formation of a thermally stable crystalline region. Furthermore, the mechanical properties of periodic copolymers were determined from the stress-strain curves of film samples.

Poly(ester-amide)s Derived From Adipic Acid, 1,4-Butanediol and β-Alanine: Synthesis and Characterization

“…The 1 H-NMR, 13 C-NMR, and FTIR spectroscopic data of all the poly(esteramide)s were in total agreement with their anticipated chemical constitution.…”

“…(7) A wide range of PEA based amino acids was mostly tested and found to be biodegradable. Therefore, PEAs have found a wide range of applications, such as agricultural films, drug carriers, drug delivery systems or hydrogels for biomedical materials (8)(9)(10)(11)(12)(13)(14).…”

Synthesis and characterization of the biomaterial poly(lactic acid‐co‐Nε‐carbobenzoyloxy‐L‐lysine) via direct melt copolymerization

“…Similarly, because of the deprotection of Lys(Z) during the melt copolycondensation under high temperatures, 27 with the introductions of ACONHA linkages 21,22,35,36 and Lys(Z) with a big aromatic ring into the copolymer, no diffraction peak was observed (Fig. 6), and all of the copolymers with different molar feed ratios were amorphous.…”

“…31,32 This was similar with reported data. 33 At the same time, the deprotection of Lys(Z) during the melt copolycondensation under high temperatures 27 and the introductions of ACONHA linkages 21,22,35,36 and Lys(Z) with a big aromatic ring into the copolymer made the structure of the resulting polymer more complex, 33 and the alignment of the polymer chains was disturbed. Therefore, T m of the relatively complex products was not observed, and no T m data are shown in Table I.…”

Inversion of crystallization rates in miscible block copolymers of poly(lactide)-block-poly(2-isopropyl-2-oxazoline)

“…31,[35][36][37] Furthermore, in poly(ester amides) with a backbone of a defined and periodic sequence of ester-and amide-groups the intermolecular interactions between esters and amides contribute considerably to thermal and mechanical stability. 38 It is thus reasonable to assume attractive dipole-dipole interactions between PLA and PiPOx and these interactions favour miscibility. IR-spectroscopy is a sensitive method to probe the molecular environment and changes of the chain conformation due to intermolecular interactions.…”