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Unformatted post-print version of the accepted article, A series of aliphatic polyethers with different chain lengths (nCH2= 6 to 12, and 16) is studied employing differential scanning calorimetry and X-rays scattering. The calorimetric and structural behavior of samples crystallized from the melt is divided into the odd-even and saturation regions. In the odd-even region (nCH2 = 6 to 10), the odd samples (nCH2 = 7, and 9) show enhanced calorimetric properties (e.g., higher transition temperatures) and faster crystallization kinetics than the even ones (nCH2 = 6, 8 and 10). The odd samples crystallize in orthorhombic unit cells and the even ones in monoclinic unit cells. In the saturation region (nCH2 = 11 to 16), the calorimetric properties increase as nCH2 increases without alternation. However, unexpectedly, the nCH2 = 12 displayed a mixed structure (monoclinic + orthorhombic) instead of an orthorhombic one. Thus, a structural saturation effect (i.e., an orthorhombic unit cell) is not reached. This particular structural feature was investigated under varied thermal histories, induced by different cooling rates. The samples as synthesized (i.e., crystallized during precipitation from solution) exhibited a structural saturation effect since both nCH2 = 10 and 12 display an orthorhombic unit cell. But, the nCH2 = 10 exhibits a monoclinic unit cell, and the nCH2 = 12 a mixed structure when the samples crystallize from the melt at different rates. Only the nCH2 = 16 crystallizes in an orthorhombic unit cell, independently of the thermal history. Thus, the complex odd-even effects in these aliphatic polyethers are a function of the cooling rate from the melt and sample preparation procedures (solution or melt crystallization).

Two series of partially biobased ABA triblock copolyesters were successfully prepared by ring-opening polymerization (ROP) of L-lactide initiated by two telechelic polyester polyols using an organic catalyst. B blocks were made of telechelic poly(hexamethylene terephthalate) (PHT) and poly(hexamethylene 2,5-furandicarboxylate) (PHF), respectively, with average molar masses of around 3500¿g¿mol-1 and A blocks were made of poly(lactic acid)s (PLA) of different block lengths. For each series, four copolymers with different PHT/PLA and PHF/PLA compositions were prepared by varying the feed molar ratios. The triblock structure of the obtained copolymers was ascertained by 13C NMR, which confirms that the organic catalyst employed does not promote transesterification reactions at the low temperatures used for the reaction. All copolyesters were thermally stable under inert atmosphere up to around 300¿°C. For all synthesized copolyesters, the PLA blocks were unable to crystallize, mainly due to racemization reactions taking place during L-lactide ROP. Both, PHT and PHF blocks were able to crystallize and their thermal and structural properties (Tm, Tc, Xc and lamellar thickness) were independent on PLA content until its concentration was very high and topological restrictions difficulted crystallization. According to SAXS, most copolymers were found to be miscible in the melt. Both PLA-b-PHT-b-PLA or PLA-b-PHF-b-PLA triblock copolymers showed a single Tg indicating that the components are miscible in the amorphous state, Peer Reviewed, Postprint (author's final draft)

Two series of partially biobased ABA triblock copolyesters were successfully prepared by ring-opening polymerization (ROP) of L-lactide initiated by two telechelic polyester polyols using an organic catalyst. B blocks were made of telechelic poly(hexamethylene terephthalate) (PHT) and poly(hexamethylene 2,5- furandicarboxylate) (PHF), respectively, with average molar masses of around 3500 g mol-1 and A blocks were made of poly(lactic acid)s (PLA) of different block lengths. For each series, four copolymers with different PHT/PLA and PHF/PLA compositions were prepared by varying the feed molar ratios. The triblock structure of the obtained copolymers was ascertained by 13C NMR, which confirms that the organic catalyst employed does not promote transesterification reactions at the low temperatures used for the reaction. All copolyesters were thermally stable under inert atmosphere up to around 300 °C. For all synthesized copolyesters, the PLA blocks were unable to crystallize, mainly due to racemization reactions taking place during L-lactide ROP. Both, PHT and PHF blocks were able to crystallize and their thermal and structural properties (Tm, Tc, Xc and lamellar thickness) were independent on PLA content until its concentration was very high and topological restrictions difficulted crystallization. According to SAXS, most copolymers were found to be miscible in the melt. Both PLA-b-PHT-b-PLA or PLA-b-PHF-b-PLA triblock copolymers showed a single Tg indicating that the components are miscible in the amorphous state.

Double crystalline multi-block copolymers exhibit two well-defined melting temperatures associated with the two phases formed by their constituent blocks. The crystalline superstructure formed in these copolymers is complex and depends on the miscibility of both comonomers. In this work, an innovative series of double crystalline Poly(ethylene terephthalate)-mb-poly(oxyhexane) multiblock copolymers were prepared in one pot. Previously synthesized low molecular weight poly(oxyhexane) telechelic diol and poly(ethylene terephthalate) oligomers were reacted by transesterification using an organic catalyst (DBU:BA), in a solvent-free process. The copolymerization was demonstrated by 1H NMR and 13C NMR spectroscopies and the random distribution of poly(oxyhexane) chains was confirmed. We found that all compositions exhibited double crystallinity, but the crystallization of the copolymers was strongly affected by PET/poly(oxyhexane) composition. When PET content in the copolymer decreases, the crystallization and melting temperatures of the poly(oxyhexane) phase decrease as well as its crystallization rate. Poly(oxyhexane) content increases induce similar changes in the PET phase. PET and poly(oxyhexane) chain segments form a one-phase melt according to SAXS. When the material is cooled from the melt, the PET phase crystallizes first (at higher temperatures) forming superstructural (micron size spherulites) templates. Upon further cooling, the crystallization of poly(oxyhexane) lamellae occurs, within the interlamellar regions of PET spherulitic templates. Furthermore, during crystallization of the copolymer, the amorphous regions of both components undergo phase separation, as evidenced by the presence of two Tgs. PLOM/AFM studies were performed and demonstrated the presence of micro-spherulitic morphology in the whole composition range. Considering all results, including temperature-dependent synchrotron SAXS/WAXS, we demonstrate the ability of poly(oxyhexane) to crystal

Isomorphism in random copolymers occurs when comonomer units can crystallize within a single crystalline lattice in the entire composition range. This ideal behavior is rare in random copolymers and only a few examples of isomorphism are found in copolyesters and copolycarbonates. In this work, we show a series of polyoxyalkylenes copolyethers obtained by copolymerization of 1,6-hexanediol and 1,12-dodecanediol which are able to crystallize in the entire composition range and display an isomorphic behavior. The copolymers were synthesized via a bulk self-condensation method at high temperature, using a thermally stable Non-Eutectic Mixture Organocatalyst (NEMO) prepared from methanesulfonic acid (MSA) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The final molar ratios of the copolyethers were calculated by 1H NMR spectroscopy and the random distribution of the two monomeric units was confirmed by 13C NMR spectroscopy. The effect of the composition of comonomer units on the crystalline structure was investigated by DSC and WAXS. The two comonomeric units along the chain can co-crystallize regardless of the composition, while displaying melting point values that vary linearly in between those of the parent homopolymers (54,9 and 84,7 °C). The crystalline reflections given by WAXS demonstrated that the two comonomers are miscible in the crystalline state and meet the general criteria to be regarded isomorphic random copolymers. Finally, a random terpolymer was synthetized from 1,6-hexanediol, 1,10-decanediol and 1,12-dodecanediol, which also shows a single melting temperature, thus demonstrating the versatility of the polymerization route employed.

Polyethers constitute a well-established class of polymers covering a wide range of applications from industrial man-ufacturing to nanomedicine. Nevertheless, their industrial implementation is limited to short chain aliphatic polyethers such as poly-ethyeleglycol (PEO or PEG), polypropyleneglycol (PPG) or polytetramethylenglycol (PTMG) produced by the ring-opening polymerization of the corresponding cyclic ethers. Herein we report a sustainable and scalable approach for the preparation of medium and long chain aliphatic polyethers by the melt self-polycondensation of aliphatic diols in the presence of non-eutectic acid base mixtures as organocatalyst. These organocatalysts were prepared by forming stoichiometric and non-stoichiometric complexes of methanesulfonic acid (MSA) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as confirmed by NMR spectroscopy and DFT calcula-tions. The non-stoichiometric 2:1 and 3:1 MSA:TBD molar complexes showed superior thermal stability. These non-eutectic acid base mixtures were tested in the bulk-self condensation of 1,6-hexanediol leading to telechelic hydroxy-poly(oxyhexane). The optimized polymerization conditions involved the use of MSA:TBD (3:1) catalyst in a three step polycondensation process at 130 oC - 180 °C and 200 °C respectively. These conditions were applied to the synthesis of a wide range of aliphatic polyethers with a number of methylene units ranging from 6 to 12 units and molecular weights between 5,000 and 22,000 g mol-1. The aliphatic polyethers were highly semicrystalline with melting temperatures ranging from 55 to 85 °C. The synthesis approach was extended to the prepa-ration of value-added copolymers from different lenght chain diols and different functionality, giving rise to different copolymer architectures from linear copolyethers to polyether thermosets. Altogether, this straightforward polymerization strategy enables the access to medium-long chain and cross-linked aliphatic polyethers using easily p

Cyclic oligomers of hexamethylene furanoate and hexamethylene terephthalate were obtained from 1,6-hexanediol and the corresponding methyl esters using Candida antarctica lipase B (CALB) enzyme catalyst. HPLC, MALDI-TOF MS, and NMR analyses showed that mixtures composed from cyclic dimer up to heptamer were obtained almost quantitatively. Subsequently, these cycles were polymerized by ring opening polymerization (ROP) mediated by CALB to obtain semicrystalline polymers. In addition, we demonstrated that the polymers obtained from the ROP process could be transformed into cyclic oligomers in high yields using enzymatic cyclodepolymerization, thereby recycling the polymer in a circular biosynthetic path., Postprint (author's final draft)