Postpolymerization Modification of Poly(dihydropyrimidin-2(1H)-thione)s via the Thiourea-Haloalkane Reaction to Prepare Functional Polymers

Ferrocene-Based Antioxidant Self-Healing Hydrogel via the Biginelli Reaction for Wound Healing

The development of antioxidant wound dressings to remove excessive free radicals around wounds is essential for wound healing. In this study, we developed an efficient strategy to prepare antioxidant self-healing hydrogels as wound dressings by combining multicomponent reactions (MCRs) and postpolymerization modification. A polymer containing ferrocene and phenylboronic acid groups was developed via the Biginelli reaction, followed by efficient modification. This polymer is antioxidant due to its ferrocene moieties and can rapidly cross-link poly(vinyl alcohol) to realize an antioxidant self-healing hydrogel through dynamic borate ester linkages. This hydrogel has low cytotoxicity and is biocompatible. In in vivo experiments, this hydrogel is superior to existing clinical dressings in promoting wound healing. This study demonstrates the value of the Biginelli reaction in exploring biomaterials, potentially offering insights into the design of other multifunctional polymers and related materials using different MCRs.

Superhydrophobic Coatings Composed of Multifunctional Polymers Synthesized Using Successive Modification of Dihydropyrimidin-2(1H)-thione

Polymer synthesis via multicomponent reactions (MCRs) has opened avenues in polymer chemistry and led to the development of various types of functional polymers. Herein, we developed a strategy to prepare multifunctional polymers via the successive modification of dihydropyrimidin-2(1H)-thione (DHPMT), which can be generated by the tricomponent Biginelli reaction. Four hydrophobic polymers were efficiently prepared by using DHPMT derivatives. These polymers can be dip-coated onto the oxidized copper mesh to obtain superhydrophobic meshes because of the strong attractive forces between the DHPMT derivatives and Cu(II). The optimized mesh has self-cleaning properties and outstanding stability in various liquid environments; it has also been successfully applied for oil/water separation with high separation efficiency and good durability. These results demonstrate that successive modification of DHPMT is a promising method for fabricating multifunctional polymers, which may have applications in polymer chemistry and materials science.

Stepping Further from Coupling Tools: Development of Functional Polymers via the Biginelli Reaction

Multicomponent reactions (MCRs) have been used to prepare polymers with appealing functions. The Biginelli reaction, one of the oldest and most famous MCRs, has sparked new scientific discoveries in polymer chemistry since 2013. Recent years have seen the Biginelli reaction stepping further from simple coupling tools; for example, the functions of the Biginelli product 3,4-dihydropyrimidin-2(1H)-(thi)ones (DHPM(T)) have been gradually exploited to develop new functional polymers. In this mini-review, we mainly summarize the recent progress of using the Biginelli reaction to identify polymers for biomedical applications. These polymers have been documented as antioxidants, anticancer agents, and bio-imaging probes. Moreover, we also provide a brief introduction to some emerging applications of the Biginelli reaction in materials and polymer science. Finally, we present our perspectives for the further development of the Biginelli reaction in polymer chemistry.

Introducing the aza-Michael addition reaction between acrylate and dihydropyrimidin-2(1H)-thione into polymer chemistry

The aza-Michael addition reaction between dihydropyrimidin-2(1H)-thione and acrylate has been used to fabricate new polymers through different synthesis routes.

Fluorescent polymers via post-polymerization modification of Biginelli-type polymers for cellular protection against UV damage

Biocompatible fluorescent polymers with UV-protective capability have been developed by the combination of the Biginelli reaction and the postpolymerization modification method.

The solvent-free one-pot multicomponent tandem polymerization of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) catalyzed by ionic-liquid@Fe3O4 NPs: the development of polyamide gels

Solvent-free MCTP via Biginelli DHPMs catalyzed by a non-toxic magnetic catalyst (IL1–2@ Fe₃O₄) in a one-pot reaction was illustrated for the development of fluorescent non-conjugated polyamide gels.

Multicomponent Reactions in Polymer Chemistry Utilizing Heavier Main Group Elements

Herein, a concise overview of the use of heavier main group elements in multicomponent reactions and their use in polymer chemistry is provided. Incorporating heavier elements into macromolecular structures via multicomponent reactions allows for the rapid development of materials with unique properties that are not readily achieved using carbon, nitrogen, and/or oxygen. Elements in Group 13, Group 14, Group 15, and Group 16 are specifically covered examining both the familiar and unfamiliar properties of these elements and how they are used in multicomponent chemistry. Furthermore, elements that both take part in the reaction mechanism and remain in the macromolecular structure upon completion are only briefly explored. Some of the state-of-the-art work going into developing these heavier element multicomponent reactions are highlighted and it is hoped to inspire other polymer chemists to explore other parts of the periodic table.

Multicomponent Radziszewski Emulsion Polymerization toward Macroporous Poly(ionic liquid) Catalysts

Interconnected macroporous imidazolium-based monoliths are produced via the modified Radziszewski multicomponent reaction (MCR) applied to triamines under high internal phase emulsion (HIPE) conditions. This straightforward one-pot synthesis combines the efficiency and versatility of MCRs with the ease of implementation of the emulsion templating polymerization process. The characterization of the chemical structure and morphology of the resulting materials confirms the formation of the expected macroporous poly(ionic liquid)s (PILs) networks. The promising catalytic activity and recyclability of these porous PIL monoliths are illustrated for the transesterification reaction and the decarboxylation of caffeic acid. In these cases, almost complete conversion is reached while benefiting from the advantages associated with a heterogeneous catalyst.

Amide transformation as an efficient postpolymerization modification approach for the synthesis of functional polyacetylenes

Modification of a precursor polyacetylene with various amines and alcohols through amide transformation gives access to a series of functional polymers showing nonlinear optical, luminescence, enhanced surface energy, and redox active properties.

Ugi Three-Component Polymerization Toward Poly(α-amino amide)s

Due to their great modularity, ease of implementation, and atom economy, multicomponent reactions (MCRs) are becoming increasingly popular macromolecular engineering tools. In this context, MCRs suitable in polymer synthesis are eagerly searched for. This work demonstrates the potential of the Ugi-three component reaction (Ugi-3CR) for the design of polymers and, in particular, of poly(α-amino amide)s. A series of polymers containing amino and amido groups within their backbone were obtained through a one-pot process by reacting aliphatic or aromatic diamines, diisocyanides, and aldehydes. The impact of temperature, concentration, catalyst loading, and substrates on polymerization efficiency is discussed. A preliminary study on the thermal properties and the solution behavior of these poly(α-amino amide)s was carried out. An aliphatic-rich derivative notably showed some pH-responsiveness in water via protonation-deprotonation of its amino groups.

Chemoselective and living/controlled polymerization of polar divinyl monomers by N-heterocyclic olefin based classical and frustrated Lewis pairs

Chemoselective and living/controlled polymerization of polar divinyl monomers by N-heterocyclic olefin based classical and frustrated Lewis pairs.

The multicomponent Debus–Radziszewski reaction in macromolecular chemistry

The well-known Debus–Radziszewski reaction is over one century old. However, this reaction has only been considered very recently as a new tool to design original imidazole and imidazolium-containing polymers by direct formation of the imidazole ring during the polymerization process. This article reports recent advances concerning the use of this newly emerging reaction in macromolecular chemistry.

Chemoselective Lewis pair polymerization of renewable multivinyl-functionalized γ-butyrolactones

Multivinyl-functionalized γ-butyrolactones, γ-vinyl-γ-methyl-α-methylene-γ-butyrolactone (γVMMBL) and γ-allyl-γ-methyl-α-methylene-γ-butyrolactone (γAMMBL), have been synthesized from biorenewable ethyl levulinate and effectively polymerized by Lewis pairs consisting of an organic N-heterocyclic carbene Lewis base and a strong organo-Lewis acid E(C6F5)3 (E = Al, B). This Lewis pair polymerization is quantitatively chemoselective, proceeds exclusively via polyaddition across the conjugated α-methylene double bond without participation of the γ-vinyl or γ-allyl double bond, and produces high-molecular-weight functionalized polymers with unimodal molecular-weight distributions. The Al-based Lewis pair produces a polymer with approximately 5.5 times higher molecular weight than that produced by the B-based Lewis pair. The resulting vinyl-functionalized polymers are soluble in common organic solvents and stable at room temperature, and can be thermally cured into crosslinked materials.This article is part of the themed issue 'Frustrated Lewis pair chemistry'.

Polymer synthesis by mimicking nature's strategy: the combination of ultra-fast RAFT and the Biginelli reaction

A two-stage method has been developed by mimicking nature's protein synthesis strategy to prepare plenty of polymers using limited monomers.

The Hantzsch reaction in polymer chemistry: synthesis and tentative application

The recent utilization of the tetra-component Hantzsch reaction in polymer chemistry has been summarized.

Multicomponent Combinatorial Polymerization via the Biginelli Reaction

A multicomponent combinatorial polymerization method has been exploited as a new intersection between combinatorial chemistry, polymer chemistry, and organic chemistry. The tricomponent Biginelli reaction has been employed as a model multicomponent reaction (MCR) to efficiently prepare a library of polycondensates with continuously changed chain structure but different physical properties. The naturally increased reaction modules (monomers) directly doubled the number of polymers in the library, effectively improving the efficiency of polymer preparation. The glass transition temperatures (Tg) of those homologous polymers have been mapped for the first time to predict the Tg values of absent polymer homologues with good to excellent accuracy. Meanwhile, the Tg maps have also been used to reveal the regular change in Tg according to the polymer structure (linking group, monomer chain length, etc.), initially suggesting the academic significance of the multicomponent combinatorial polymerization system. We believe that the current research paves a straightforward way to synthesize new libraries of polymers via MCRs and might prompt the broader study of MCRs in interdisciplinary fields.

Organocatalytic and Chemoselective Polymerization of Multivinyl-Functionalized γ-Butyrolactones

Achieving complete chemoselectivity in the polymerization of multivinyl polar monomers is an important yet challenging task, currently achievable only by metal- or metalloid-mediated polymerization processes but in a noncatalytic fashion. Now this work shows that organic N-heterocyclic carbene (NHC) catalysts effect rapid, chemoselective, and catalytic polymerization of multivinyl-functionalized γ-butyrolactones, particularly γ-vinyl-α-methylene-γ-butyrolactone (VMBL). Thus, the NHC-catalyzed polymerization of VMBL not only is quantitatively chemoselective, proceeding exclusively via polyaddition across the conjugated α-methylene double bond while leaving the γ-vinyl double bond intact, but also requires only an exceptionally low catalyst loading of 50 ppm, thus, exhibiting a remarkably high catalyst turnover frequency of 80000 h^-1 and producing on average 33.6 polymer chains of M_n = 73.8 kg/mol per NHC molecule. The resulting PVMBL can be either thermally cured into cross-linked materials or postfunctionalized with the thiol-ene "click" reaction to achieve complete conversion of the pendant vinyl group on every repeat unit into the corresponding thioether.

Lighting up the PEGylation agents via the Hantzsch reaction

PEG chain ends have been modified with a protein reactive-group through the Hantzsch reaction to in situ achieve fluorescent PEGylation agents for protein conjugation.

Multicomponent Copolycondensates via the Simultaneous Hantzsch and Biginelli Reactions

The tricomponent Biginelli reaction and the tetracomponent Hantzsch reaction which share the same reaction modules (aldehyde and β-ketone ester) have been found compatible. Therefore, a series of copolycondensates containing both 1,4-dihydropyridine (1,4-DHP) and 3,4-dihydropyrimidin-2(1H)-one (3,4-DHPM) in the main chains via the simultaneous Hantzsch and Biginelli reactions have been facilely synthesized. The ratio of 1,4-DHP and 3,4-DHPM in the polymer congeners could be easily tuned by changing the feeding ratio of reactants, and the thermal properties of the obtained polymers are thereby adjusted. As the first attempt to prepare copolycondensate through the combination of two multicomponent reactions (MCRs), the current method revealed and utilized the interesting compatibility between MCRs, providing a new strategy to prepare multicomponent functional polymers.