Synthesis, Crystallization, Structure Memory Effects, and Molecular Dynamics of Biobased and Renewable Poly(n-alkylene succinate)s with n from 2 to 10

Abstract

In this article, we synthesize five poly(n-alkylene succinate)s, PnASs, with n = 2, 4, 6, 8, and 10 via multi-step polycondensation methods. Next, we comparatively investigate these renewable and biobased polyesters from the points of view of structure, crystallinity, and molecular mobility, employing 1 H nuclear magnetic resonance spectroscopy, size-exclusion chromatography, viscometry, X-ray diffraction, differential scanning calorimetry (DSC, conventional and temperature modulation modes), polarized optical microscopy (POM), and broadband dielectric relaxation spectroscopy (BDS). Next to the successful synthesis of the materials, we evaluate the characteristics of crystallization (temperature and fraction); moreover, we explore for the first time, on the same type of succinic polyesters, the impact of n on the structure memory related to crystal nucleation as well as the changes in the semicrystalline morphology. We demonstrate that the structure/crystal memory is stronger for the lower n (shorter alkylene succinate monomers) because of more chain−chain associations, the result being independent from the overall length of the polymer chain (molar mass, M n 13−80 kg/mass). The crystalline fraction (CF ∼ 12− 34%) increases with n, also independently from M n ; however, the chain length affects directly the nucleation rate as T c increases with M n . The direct effects of n, in the inter-/intrachain interactions, as well as the indirect ones, on the CF and distribution of crystallites were found to be responsible for the alternations in the static glass transition temperature in DSC (lowering of T g with n) and the dynamic glass transition (α, α c relaxations in BDS). For the sum of these PnASs, the molecular dynamics mapping is shown here, also for the first time. With increasing n, segmental dynamics accelerates, whereas, interestingly, the cooperativity drops (elimination for n = 10). Comparing these results with the recorded alternations in the semicrystalline morphology (POM), we conclude spatial confinement to be imposed on the mobile amorphous polymer by the tightly distributed crystallites when n increases. Overall, these data provide proofs for the potential for tuning of the final polymer properties connected with crystallization (mechanical performance and permeability), envisaging future biomedical, packaging, and other application for these PnASs.

Thermal Stability and Decomposition Mechanism of Poly(alkylene succinate)s

“…All polyesters were semicrystalline materials. PBSu displayed the highest melting point (117.8 • C) while PHSu had the lowest (64.2 • C), which is in good agreement with our previous work [34]. All other polyesters had intermediated melting points, as presented in Table 2.…”

“…These polyesters were previously thoroughly examined and reported from the points of view of structure, crystallinity, and molecular mobility [33,34]. According to the aforementioned studies, it was assumed that the simple manipulation of the monomer structure provokes remarkable alterations in the semi-crystalline structure and tuning of the polymer chains diffusion, while it was clearly evidenced that the final polymeric properties, including for instance mechanical performance, degradation rate, and permeability are strongly affected by the crystallization profile.…”

Direct and indirect effects on molecular mobility in renewable polylactide–poly(propylene adipate) block copolymers as studied via dielectric spectroscopy and calorimetry

“…These interactions are expected to hinder the chain mobility (diffusion and cooperativity) and be pronounced for shorter chains. [55][56][57] Coming to the strength of glass transition, the M n dependence of Dc p is shown in Fig. 4b.…”

Unlayered–Layered Crystal Transition in Recyclable Long-Spaced Aliphatic Polyesters

“…21,25,26 For aliphatic polyesters, ester layer packing is expected to be driven by dipole−dipole interactions. 7,27,28 Interactions between the esters of adjacent chains reduce the enthalpic penalty that occurs as a result of incorporating ester groups into the crystal lattice. Despite the presence of the ester groups within crystallites, LSAPEs maintain a polyethylene-like orthorhombic crystal lattice, 11,17,18 meaning that van der Waals interactions between adjacent CH 2 sequences play the major role in determining the drive for crystallization.…”