Long chain branches (LCB) affect the rheology, nucleation, and crystallization of polymers. We have studied the role of LCB in isotactic polypropylene (iPP) under shear-free conditions on the primary nucleation and overall crystallization of iPP. Samples were prepared by solution casting to eliminate any shear effects. The iPP nucleation density increased with branching content, as demonstrated by Polarized light optical microscopy (PLOM) and scanning electron microscopy (SEM). Standard differential scanning calorimetry (DSC) and ultra-fast scanning chip calorimetry (or FSC, Fast Scanning Calorimetry) allowed covering a wide temperature range for isothermal crystallization in the entire crystallization window (5-136°C). Above 95°C, only the α-phase of iPP formed, with an increasing crystallization rate with branching content. In addition to the typical heterogeneous nucleation, the LCBs provoke a significant increase in the homogeneous nucleation process triggered by topological constraints of the chain segments linked to the branch point. These constraints stabilize the PP chain's helical structure and induce the self-assembly of these neighboring chains into primary nuclei. Homogeneous nucleation became dominant below 45°C, where the supercooling was high. Similar results have been found in Poly(lactic acid) containing LCB. Our results indicate that the overall crystallization kinetics of LCB-containing polymers can be significantly influenced by homogeneous nucleation processes that depend on the crystallization temperature.

The even-odd effect in polymers refers to an alternating (zig-zag) behavior of physical properties with the number of CH2 in the main chain depending on whether the polymer has an even or an odd number of CH2 groups in its repeating unit. Usually those polymers have strongly interacting functional groups within polymer repeating units. The even-odd effect has been reported for several polymer families including polyesters, polyurethanes, or polyamides and properties such as thermal behaviour, mechanical performance or optical properties can be affected.
Nevertheless, there is still a lack of in-depth studies that establish relationship between the even-odd effect with the structural changes. In order to asses this knowledge gap, we have investigated poly(ester amide)s containing long alkyl chain lengths correlating its structure with the thermal properties. The materials display an even odd effect in the thermal properties including melting temperature and crystallinity degree and in the spherulitic morphology with odd samples showing banding. The even odd effect persist in poly(ester amide)s even with 27 CH2 groups in the repeating unit, which arises from the strong hydrogen groups from amide group. The X ray studies show that the even-odd effect results from the modification of the crystalline structure of the polymer.
Overall, this work shows that by designing carefully polymer systems with tailored intermolecular interactions considering the alkyl chain length, it is possible to fine-tune the thermal properties opening the door to control the final performance of semicrystalline materials.

Random copolymers crystallize in three modes according to the comonomer inclusion/exclusion balance during crystallization: isodimorphism, isomorphism, and comonomer exclusion. (1,2) Considering a PAxBy copolymer, in the comonomer exclusion case, the B co-units are excluded from PA crystals, limiting their crystallization to a narrow composition range and vice-versa, leaving a wide intermediate composition range without crystallization. In contrast, in isomorphic copolymers, total comonomer inclusion leads to the formation of a new phase, PA-B, in all composition ranges, that differs from that of the homopolymers. As a result, the properties, such as the melting temperature (Tm), vary linearly with composition. Finally, isodimorphism can be regarded as an intermediate case (with a comonomer inclusion/exclusion balance) in which partial comonomer inclusion leads to crystallization for all compositions. But, due to the excluded co-units, there is a Tm depression as a function of the composition, resulting in a pseudo-eutectic behavior, also extrapolated to other properties. Recently, in copolycarbonates (3,4), we have found that even though they show the main features of isodimorphism, they display atypically high crystallinity degrees and the formation of a new crystalline phase in a limited composition range. Therefore, they can be considered as a new mixed isodimorphic/isomorphic crystallization mode. Similarly, in copolyesters,(5) we found the absence of comonomer inclusion on one side of the pseudo-eutectic, thus defining another new mixed comonomer exclusion/isodimorphism crystallization. These findings represent two novel crystallization modes for random copolymers.

Achieving controlled and reversible covalent bond manipulation is critical for advancing recyclable and reprocessable materials. Our work establishes quinolinone motifs as highly versatile, multi-stimuli-responsive building blocks for orthogonal covalent-gated chemistry, leveraging a reversible [2π+2π] cycloaddition mechanism activated by light and/or heat.
A systematic evaluation of photocycloadditions and cycloreversions across various wavelengths and conditions identifies optimal parameters for highly effective, orthogonal photoreactions, achieving nearly 100% yield. When combined, these photoprocesses exhibit exceptional cyclability, sustaining performance over eight cycles—an outcome rarely observed in similar systems. Further integration of quinolinones into oligomers enables catalyst-free, fully reversible photopolymerization in solution. This process yields polymers with molecular weights up to 60 kDa, which can fully depolymerize back into their monomeric building blocks over multiple cycles. A key discovery reveals the tunable influence of oxygen, which redshifts the reversion process while preserving high conversion and cyclability, greatly expanding the system's versatility.
Further studies at the molecular level demonstrate, for the first time, that quinolinone dimers undergo quantitative thermal cycloreversion, achieving over 99% monomer recovery within just 10 minutes at 210 °C in the solid state. Incorporating these motifs as pendant groups in polymers enables light-induced crosslinking and thermally triggered cleavage of solid-state polymer networks, offering a novel approach to recycling polymer networks. Beyond its recycling potential, this study demonstrates the ability of this system to precisely tune material properties by adjusting processing times, allowing for controlled crosslinking and deconstruction. This capability supports the development of advanced functional materials, such as coatings with customizable debonding properties.