In the present paper, four fully biobased homopolyesters of 2,5-furandicarboxylic acid (2,5-FDCA) with a high molecular weight have been successfully synthesized by two-stage melt polycondensation, starting from the dimethyl ester of 2,5-FDCA and glycols of different lengths (the number of methylene groups ranged from 3 to 6). The synthesized polyesters have been first subjected to an accurate molecular characterization by NMR and gel-permeation chromatography. Afterward, the samples have been successfully processed into free-standing thin films (thickness comprised between 150 to 180 μm) by compression molding. Such films have been characterized from the structural (by wide-angle X-ray scattering and small-angle X-ray scattering), thermal (by differential scanning calorimetry and thermogravimetric analysis), mechanical (by tensile test), and gas barrier (by permeability measurements) point of view. The glycol subunit length was revealed to be the key parameter in determining the kind and fraction of ordered phases developed by the sample during compression molding and subsequent cooling. After storage at room temperature for one month, only the homopolymers containing the glycol subunit with an even number of −CH 2 – groups (poly(butylene 2,5-furanoate) (PBF) and poly(hexamethylene 2,5-furanoate) (PHF)) were able to develop a three-dimensional ordered crystalline phase in addition to the amorphous one, the other two appearing completely amorphous (poly(propylene 2,5-furanoate (PPF) and poly(pentamethylene 2,5-furanoate) (PPeF)). From X-ray scattering experiments using synchrotron radiation, it was possible to evidence a third phase characterized by a lower degree of order (one- or two-dimensional), called a mesophase, in all the samples under study, its fraction being strictly related to the glycol subunit length: PPeF was found to be the sample with the highest fraction of mesophase followed by PHF. Such a mesophase, together with the amorphous and the eventually present crystalline phase, significantly impacted the mechanical and barrier properties, these last being particularly outstanding for PPeF, the polyester with the highest fraction of mesophase among those synthesized in the present work.

Article title: Evidence of a 2D-ordered structure in biobased poly(pentamethylene furanoate) responsible for its outstanding barrier and mechanical properties 5 Pages 6 Figures S2 Figure S1. dP vs. time for O 2 Figure S2. dP vs. time for CO 2 Sample Data Sample No. Order No. Sample Type Sample Name Received Tested by Request°C % Rel. Humidity Pre-conditioning Hrs.°C % Rel. Humidity Room Conditions Test Temperature°C mm³ Volume Device Number cm³/min % Rel. Humidity Gas Stream cm² Layer Sample Area Mask Test Gas Solubility cm³/cm³ bar Diff. Coeff.

Isodimorphic random copolyesters are intriguing polymeric materials that can crystallize in their entire composition range, despite the random distribution of comonomer units along their chains. This behavior stems from the relatively similar chemical repeating units of the parent homopolymers. In this feature article, we review our recent works on isodimorphic aliphatic copolyesters, and extract general trends in the framework of the literature. Isodimorphic behavior is a complex phenomenon driven by comonomer partition within the crystalline unit cells formed. These copolyesters crystallize in the entire composition range displaying a pseudo-eutectic behavior when their melting points are plotted as a function of composition. Two crystalline phases, which resembled the crystalline structures of the parent homopolymers, are formed, depending on the considered composition range. The unit cell dimensions of the parent homopolymers change, as a consequence of the inclusion of co-units. At the pseudo eutectic point or pseudo-eutectic region, two crystalline phases can co-exist and their formation strongly depends on thermal history. In this case, double crystalline random copolyesters with two melting points and mixed double-crystalline spherulites can be obtained. The exact composition of the pseudo-eutectic point, the level of comonomer inclusion and the crystallinity degrees cannot be easily predicted by the copolyester chemical structure and composition. These are important issues for further future studies, as well as the quantitative determination of comonomer inclusion in the generated crystalline phases. The extraordinary variation of thermal properties, morphology and crystallinity that isodimorphic random copolyesters display as a function of composition, allows to conveniently tailor their biodegradation, permeability to gases and mechanical properties.

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Both academia and industry are currently devoting many efforts to develop high gas barrier bioplastics as substitutes of traditional fossil-based polymers. In this view, this contribution presents a new biobased aromatic polyester, i.e., poly(propylene 2,5-thiophenedicarboxylate) (PPTF), which has been compared with the furan-based counterpart (PPF). Both biopolyesters have been characterized from the molecular, thermo-mechanical and structural points of view. Gas permeability behavior has been evaluated with respect to 100% oxygen, carbon dioxide and nitrogen at 23 • C. In case of CO 2 gas test, gas transmission rate has been also measured at different temperatures. The permeability behavior at different relative humidity has been investigated for both biopolyesters, the thiophen-containing sample demonstrating to be better than the furan-containing counterpart. PPF's permeability behavior became worse than PPTF's with increasing RH, due to the more polar nature of the furan ring. Both biopolyesters under study are characterized by superior gas barrier performances with respect to PEF and PET. With the simple synthetic strategy adopted, the exceptional barrier properties render these new biobased polyesters interesting alternatives in the world of green and sustainable packaging materials. The different polarity and stability of heterocyclic rings was revealed to be an efficient tool to tailor the ability of crystallization, which in turn affects mechanical and barrier performances.

In this work, we report on the surface patterning of semiconducting Poly(3-hexylthiophene) (P3HT) thin films by means of Laser Induced Periodic Surface Structures (LIPSS). Two different laser wavelengths, 266 nm and 532 nm, and a broad range of fluences and number of pulses have been used in order to optimize the LIPSS morphology. Ripples period and depth can be tuned by laser parameters. In particular, the high optical absorption of P3HT at 532 nm enables the formation of well-ordered nanostructures with periodicities around 460 nm. Near Edge X-ray Absorption Fine Structure (NEXAFS) and Raman spectroscopy reveal a good chemical stability of P3HT thin films during LIPSS formation. Conducting Atomic Force Microscopy (C-AFM)

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