Recent advances in macromolecular chemistry have revolutionized the way we perceive the synthesis of polymers. Polymerization, to be modern, must be "controlled", which usually means capable of producing macromolecules of well-defined structure. The purpose of this review is to examine how the chemistry of epoxy resins, an almost century-old chemistry, is also involved in this movement. Epoxy resins are characterized by both the flexibility of implementation and the qualities of the polymers obtained. Key materials in health-, mobility-and energy related technologies, these resins are heavily present in high-performance composites, electronic boards, adhesives and coatings. Currently, a large number of resins and hardeners are available on the market or described in the literature and an interesting point is that almost any combination of the two is possible. Common to all these recipes and processes is that a liquid (or soluble) resin at some point becomes insoluble and solid. It is very important to know how to manage this transition, physically known as the gel point, as it is the point after which the shape of the object is irreversibly set. Taking into account the variety of epoxy polymerization processespolyaddition, anionic or cationic polymerization-we detail a number of methods to program the occurrence of the gel point and how this type of control affects the structure of the growing network.

A lamellar diblock polymer combining a cross-linkable segment with a chemically etchable segment was cross-linked above its order–disorder temperature (TODT) to kinetically trap the morphology associated with the fluctuating disordered state. After removal of the etchable block, evaluation of the resulting porous thermoset allows for an unprecedented experimental characterization of the trapped disordered phase. Through a combination of small-angle X-ray scattering, nitrogen sorption, scanning electron microscopy, and electron tomography experiments we demonstrate that the nanoporous structure exhibits a narrow pore size distribution and a high surface to volume ratio and is bicontinuous over a large sample area. Together with the processability of the polymeric starting material, the proposed system combines attractive attributes for many advanced applications. In particular, it was used to design new composite membranes for the ultrafiltration of water.

Improving the sustainability of polymer networks is a crucial challenge in polymer science due to their important role in industry. Their traditional syntheses conflict with several principles of green chemistry as the employed monomers are petroleum-based, their production involves the use of toxic reagents, and their permanently cross-linked structures impede their chemical recycling and reshaping. The development of vitrimers represents a unique solution to address the issue of polymer network end-of-life by enabling reprocessability while maintaining good thermomechanical properties and solvent resistance. Although over the last decades biomass has proved to be an excellent feedstock for the production of permanently cross-linked polymers, the field of biobased vitrimers is still in its infancy. In this review, a comprehensive overview of vitrimers synthesized from biobased monomers is presented. The emphasis is set on the compatibility of the biomass structure with the nature of the dynamic covalent chemistry, as well as the sustainability of the synthetic approaches. Implementing renewable feedstocks and recyclability in the production of polymer networks paves the way for the development of the next generation of sustainable materials.

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Solution-cast blends of lamellar-forming poly­(styrene-stat-butadiene)-block-poly­(lactide), P­(S-s-B)-b-PLA, and peroxide were heated above their effective order–disorder transition temperature, T ODT, to chemically arrest the locally segregated and bicontinuous domains of the block polymer in the fluctuating disordered state. Selective hydrolysis of the PLA domains produced porous networks characterized by using a combination of small-angle X-ray scattering, scanning electron microscopy, and nitrogen sorption analysis. The location of T ODT varied with parameters of the curing system, including peroxide identity and loading, leading to observable changes in the product morphology and pore characteristics with curing temperature. Disordered, bicontinuous structures exhibiting narrow pore size distributions were generated in several cases, rendering the materials attractive for size-selective membrane applications. The versatility of the radical curing approach is highlighted via extension of the solution-based casting protocol toward the preparation of selective membranes for ultrafiltration.

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The cationic ring-opening polymerization (ROP) of room temperature curable epoxy compositions was investigated in the presence of protic (alcohols), weakly chelating (linear polyethers), and strongly chelating (crown ethers) species. Epoxide conversion and gelation were monitored through infrared and rheological measurements. We demonstrate that the propensity of hydroxyl moieties to promote the activated monomer (AM) mechanism and the chelating ability of polyether groups toward the cationic species involved in this propagation mode can be combined to control two fundamental parameters of the gelation process of epoxy resins, the gel time (t gel) and the critical conversion (conversion at the gel point, x gel), by adequately adapting the amount of these additives. In the case of crown ether, a strong synergy between these two control tools was found and interpreted by the prolonged stabilization of protons involved in chain transfers, in the form of dormant supramolecular host–guest complexes. These results underline the potential of this new approach to control both the kinetic and architecture of epoxy growing network.

The carbonation of biosourced 1,2-diols is a sustainable avenue for the synthesis bis-five-membered cyclic carbonates (bis-5CCs), the precursors of a valuable class of polymers, for example, polyhydroxyurethanes (PHUs). In this work, we performed the direct carbonation of optically pure sugar-based butadiene tetraols, namely, (i) meso-erythritol and (ii) its (S,S) diastereoisomer, (L)-threitol. The corresponding vicinal bis-5CCs, erythritol dicarbonate (EDC) and threitol dicarbonate (TDC), respectively, retain the stereochemistry of the starting tetraols. The comprehensive study of their aminolysis reaction, in DMSO and at room temperature, indicates that the kinetics and the regio-orientation of the ring opening of the 5CC are very much dependent on their stereochemistry. The total aminolysis of EDC results in the formation of hydroxyurethanes with an excess of secondary hydroxyl groups, (OH) II , of about 85%, against 60% for TDC. Moreover, when considering the two consecutive aminolyses of EDC (and TDC, respectively), the kinetic rate constant of the first aminolysis k 1,EDC (and k 1,TDC , respectively) is 1 order of magnitude higher than that of the second aminolysis, k 2,EDC ∼ k 1,EDC /10 (and k 2,TDC ∼ k 1,TDC /10, respectively). We used this feature to develop a onepot, two-step polymerization procedure, offering sequence-controlled PHUs. All the experimental results are well supported by density functional theory calculations. In the end, the comparative study of these two diastereoisomers of simple sugar-based vicinal bis-5CCs provides a new family of PHUs with tunable sequence-and regioregularities.