Biodegradable poly(ethylene succinate) (PES). 2. Crystal morphology of melt-crystallized ultrathin film and its change after enzymatic degradation

Preparation of Keggin-type monosubstituted polyoxometalate ionic liquid catalysts and their application in catalyzing the coupling reaction of ethylene carbonate and dimethyl succinate to synthesize poly(ethylene succinate)

A series of Keggin-type monosubstituted polyoxometalate-ionic liquids catalysts (POM-ILs) were synthesized. The chemical structure, crystal structure, catalyst morphology, elemental and thermal stability properties of POM-ILs were characterized and analyzed. And...

Renewable polymers and plastics: Performance beyond the green

Renewable bio-based polymers are one of the effective answers that the bioeconomy offers to solve the environmental emergency connected to plastics and more specifically fossil-based plastics. Previous studies have shown that more than 70 % of the natural capital cost associated with plastic derives from the extraction and processing of fossil raw materials and that the price of fossil plastic would be on average 44 % higher if such impact was fully paid by businesses. The disclosure of the hidden costs of plastics will contribute to dispelling the myth of the expensiveness of renewable polymers. Nevertheless, the adoption of bio-based plastics in the market must be motivated by their functional properties and not merely by their green credentials. This article highlights some successful examples of synergies between chemistry and biotechnology in achieving a new generation of bio-based monomers and polymers. Their success is justified by the combination of scientific advances with positive environmental and social fallouts.

Structure and Dynamics of Biobased Polyester Nanocomposites

The structure and the dynamics of two bio-based polyester polyols are investigated in the bulk and close to surfaces in polymer/layered silicate nanocomposites. The morphology of the neat polymers as well as the structure of the nanohybrids are investigated with X-ray diffraction and their thermal properties are studied by differential scanning calorimetry. One of the investigated polyesters is amorphous, whereas the second one is a semicrystalline polymer with intriguing thermal behavior. Hybrids have been synthesized over a broad range of compositions and intercalated structures are always obtained. The thermal transitions in the nanocomposites are observed only when the polymers are in excess outside the completely filled galleries. The glass transition, whenever it can be resolved, appears insensitive to the presence of the inorganic material, whereas the way the crystallization takes place depends on the composition of the nanohybrid. Dielectric relaxation spectroscopy was utilized to study the polymer dynamics. It revealed multiple relaxation processes for the neat polymers both below and above their glass transition temperatures, whereas in the nanocomposites, similarities and differences are observed depending on the specific mode of the dynamic process.

Effect of Hydroxyl Monomers on the Enzymatic Degradation of Poly(ethylene succinate), Poly(butylene succinate), and Poly(hexylene succinate)

Poly(ethylene succinate) (PES), poly(butylene succinate) (PBS), and poly(hexylene succinate) (PHS), were synthesized using succinic acid and different dihydric alcohols as materials. Enzymatic degradability by cutinase of the three kinds of polyesters was studied, as well as their solid-state properties. The biodegradation behavior relied heavily on the distance between ester groups, crystallinity, and the hydrophilicity-hydrophobicity balance of polyester surfaces. The weight loss through degradation of the three kinds of polyesters with different hydroxyl monomers took place in the order PHS > PBS > PES. The degradation behavior of the polyesters before and after degradation was analyzed by scanning electron microscopy, differential scanning calorimetry, powder X-ray diffraction, Fourier transform infrared spectroscopy, gel permeation chromatography, and thermogravimetric analysis. The decrease in relative intensity at 1800–1650 estedpolyesters were degraded simultaneously. The frequencies of the crystalline and amorphous bands were almost identical before and after degradation. Thus, enzymatic degradation did not change the crystalline structure but destroyed it, and the degree of crystallinity markedly decreased. The molecular weight and polydispersity index only changed slightly. The thermal stability of the three kinds of polyesters decreased during enzymatic degradation.

Incorporation of inorganic fullerene-like WS2 into poly(ethylene succinate) to prepare novel biodegradable nanocomposites: a study on isothermal and dynamic crystallization

Novel biodegradable nanocomposites based on PES and environmentally-friendly IF-WS₂ were prepared with enhanced crystallization behavior in isothermal and non-isothermal modes.

Synthesis and properties of novel poly(ethylene succinate-co-decamethylene succinate) copolymers

The tensile properties of poly(ethylene succinate-co-decamethylene succinate) copolymers may be well regulated by the decamethylene succinate contents.

Enhanced crystallization rate of biodegradable poly(butylene succinate-co-ethylene succinate) by poly(butylene fumarate) as an efficient polymeric nucleating agent

PBF may significantly enhance the nonisothermal melt crystallization behavior of biodegradable PBES by acting as an efficient polymeric nucleating agent.

Synthesis, properties and applications of biodegradable polymers derived from diols and dicarboxylic acids: from polyesters to poly(ester amide)s

Poly(alkylene dicarboxylate)s constitute a family of biodegradable polymers with increasing interest for both commodity and speciality applications. Most of these polymers can be prepared from biobased diols and dicarboxylic acids such as 1,4-butanediol, succinic acid and carbohydrates. This review provides a current status report concerning synthesis, biodegradation and applications of a series of polymers that cover a wide range of properties, namely, materials from elastomeric to rigid characteristics that are suitable for applications such as hydrogels, soft tissue engineering, drug delivery systems and liquid crystals. Finally, the incorporation of aromatic units and α-amino acids is considered since stiffness of molecular chains and intermolecular interactions can be drastically changed. In fact, poly(ester amide)s derived from naturally occurring amino acids offer great possibilities as biodegradable materials for biomedical applications which are also extensively discussed.

Urethane Ionic Groups Induced Rapid Crystallization of Biodegradable Poly(ethylene succinate)

Novel urethane ionic groups were incorporated into biodegradable poly(ethylene succinate) (PES) by chain extension reaction of PES diol (HO-PES-OH) and diethanolamine hydrochloride (DEAH) using hexamethylene diisocyanate (HDI) as a chain extender. The synthesized polymer was a novel segmented poly(ester urethane) ionomer (PESI) in which the soft segments were formed by reaction of HO-PES-OH with HDI and the hard segments that contained ionic groups were derived from reaction of DEAH with HDI. The crystallization rate of PESI was dramatically accelerated when 3 mol % urethane ionic groups were incorporated. However, the crystallization mechanism did not change. The significant acceleration in crystallization rate was attributed to the improved nucleation efficiency by incorporation of the urethane ionic group, because PESI showed significantly enhanced nucleation density but slightly slowed spherurlitic growth rate in comparison with PES which was synthesized by chain extension reaction of HO-PES-OH with HDI. The increased nucleation efficiency was ascribed to the aggregation of hard segments of PESI induced by the ionic interactions.

Crystalline Structure of Poly(hexamethylene adipate). Study on the Morphology and the Enzymatic Degradation of Single Crystals

The crystalline structure of polyester 6 6 was studied by means of X-ray and electron diffraction and real-space electron microscopy. An orthorhombic unit cell containing eight chain segments with a quasi planar zigzag conformation was derived. The chain axis projection could be defined by a small rectangular cell containing only two molecular segments. Simulation of electron diffraction patterns indicates that molecular segments were arranged with azimuthal angles close to +/-46 degrees . X-ray diffraction patterns suggested that the large dimensions of the unit cell were a consequence of a slight shift between neighboring chains that improved the electrostatic interactions. Chain-folded lamellar crystals were obtained by isothermal crystallization of dilute n-hexanol or n-octanol solutions. The crystalline habit was studied, and the influence of temperature was evaluated. A regular folding surface was observed by using polyethylene decoration techniques. Lamellar crystals were easily degraded with different lipases. A preferential enzymatic attack was, in some cases, observed to occur in the crystal edges, giving rise to highly irregular borders with a fringed texture.