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A catalyst-free and thermal-induced S→O acetyl migration (SOAM) reaction was occasionally found and used to fabricate the polythiol corrosion inhibitor. The route to prepare the polythiols was free of catalyst and side products. Only intramolecular migration process existed, while intermolecular migration was not found. Temperature-dependent 1H NMR experiment showed the conversion rate of the SOAM reaction was 83% at 160 °C. Further heating at higher temperature or for longer reaction time, the conversion rate did not increase. It was speculated that there was equilibrium between two reversible migrations. The prepared polythiol inhibitor contains a large amount of latent thiol groups after the SOAM reaction process. The strong Cu S bonds immediately formed and made the polythiol chains firmly anchored on the copper surface when the copper metal was coated with the polythiols. Also S S bond formation reaction leads to dense crosslinking and film formation. Raman spectrum and SEM were used to characterized the protective film. A smooth and defect-free film with thickness of 1.9 μm was achieved when the copper sample was immersed in the polythiol solution for 60 min. The corrosion performance of the film is obtained by potential and impedance measurements and Tafel curves by immersing in a 3.5 wt% NaCl solution. All of the coated samples exhibited significantly lower corrosion rates than the bare copper sample, and the corrosion rate decreased as the immersion time increased. The inhibtion efficiency of the polythiol inhibitor was up to 99.3%. Neutral salt spray experiments indicated that the polythiol films provided excellent protection for over one week. The polythiols were also very stable in storage and have application in designing various polyacrylate polythiols resins.

Mesoporous nanospheres are of great importance in the cutting-edge fields of energy, catalysis and sensor technology, mainly because of their multilevel architectures, tunable meso-structures, specific compositions and soft-templated synthesis approaches. In this review, the control mechanisms of aqueous polymer self-assembly are first elaborated based on the correlated driving forces, methods, and initial conditions. Then, recent advances of co-assembly-driven nanocomposite formation techniques toward mesoporous nanosphere engineering using amphiphilic block copolymers and low-molecular-weight surfactants as soft templates are systematically reviewed. Here, soft templates and organic or inorganic precursor species as well as their co-assembly processes and formation mechanisms are elaborated to thoroughly understand co-assembly-driven nanocomposite formation techniques. After soft template removal through high-temperature pyrolysis or solvent extraction, mesoporous nanospheres can be obtained. Generally, this review presents insights and a guideline to co-assembly-driven engineering of mesoporous nanospheres and promotes the development of this emerging interdisciplinary research field at the frontier between organic polymer co-assembly and inorganic nanomaterial fabrication.

Hyperbranched star copolymers are important soft materials that have been employed for aqueous self-assembly and bioapplication, but their one-pot one-batch synthesis strategy and relevant topology are rarely discussed. In this contribution, we produce hyperbranched star poly(vinyl ether ester)s (mPEG-hb-PVEEs) amphiphiles with multimodal molecular weight distribution via one-pot one-batch Am+Bn+C1 (m ≥ 2, n ≥ 3) step-growth polymerization. Based on the topological analysis of these hyperbranched star copolymers, a convenient expression of the number ratio of monomeric structural units (NA/NB) is deduced to describe the cyclic defect of intramolecular cyclization only by using proton nuclear magnetic resonance spectroscopy. The introduction of long-chain terminators and the change in the molar feed ratio of A2:B3:C1 considerably affect the NA/NB so as to give rise to increased influence of number of macromolecules and decreased influence of intramolecular cyclization, which are then responsible for an aqueous self-assembly behavior of mPEG-hb-PVEEs amphiphiles. Overall, this study opens new possibilities for the precise description of intramolecular cyclization and controllable synthesis of hyperbranched star copolymers via one-pot Am+Bn+C1 step-growth polymerization.

Synthesizing and characterizing sequence-defined polymers with positively charged backbone are great challenges. By alternately processing Menschutkin reaction and Cu-catalyzed azide-alkyne cycloaddition reaction, we successfully synthesized series of scalable cationic sequence-defined polymers with quaternary ammonium backbone up to 12 repeating units and characterized their precise structures. Due to the dramatic polarity difference between weak polar feed molecules and strong polar target molecules, simple precipitation in weak polar solvents is enough to obtain pure sequence-defined polymers. Such a polar-inverse strategy (PIS), without protecting groups and solid support, offers extremely high yields up to 68% after 12 reaction steps (i.e., average yield95% for each step), favoring cost-effective large-scale production. Because of the independent reactivity of selected functional groups, the cationic sequence-defined polymers are highly programmable, including backbone composition, sequence order, functional side groups, terminal groups and topological structure. Sequence information decoding is easily achieved according to Maldi-Tof mass spectrum without retrospecting its synthetic history, resulting in a great superiority in the field of information transmitting and reading. The resulting multifunctional sequence-defined polymers are water-soluble and positively charged, opening the avenue to bioapplications such as condensing DNA, gene transfection and drug delivery.

We have coined a new term, group interval-controlled polymers (GICPs), to describe the unique structure of macromolecules with a tunable functional group interval. The precise control of a polymer main chain structure itself is still a big challenge, let alone the purposeful control of group interval simultaneously. Here, we successfully synthesized a series of epoxy GICPs via one-step UV-triggered thiol–yne polymerization of commercial glycidyl propargyl ether and dithiols at 0 °C. Subsequently, α,ω-thiols of each epoxy GICP were capped by two allyl glycidyl ethers via a thiol–ene click reaction, affording a stable product. Their unique group interval-controlled chemical structures were confirmed by a combination of nuclear magnetic resonance (NMR), gel permeation chromatography (GPC) and pyrene-fluorescent probe tests. Moreover, the epoxy groups within the GICPs were highly reactive and could be further functionalized and turned into a diverse range of customized groups such as azide, tertiary amino, thioester, and hydroxyl, etc. Therefore, a series of GICPs with designed functional groups are readily achieved on a large scale. Our work presents a reliable synthetic methodology for GICPs, paving a new way for the precise structure control of artificial macromolecules.

Porous polymer microspheres have been widely used in various fields, such as in ion-adsorption and drug release, and as catalyst carriers and so on. However, the facile synthesis of polymer microspheres with various available functional groups is still a challenge. Here, we firstly synthesized epoxy-functionalized porous microspheres via thiol–yne suspension polymerization of glycidyl propargyl ether and 1,3-propanedithiol, using 1,7-octadiyne as a crosslinker and polyethylene glycol (PEG) as a porogen. The epoxy groups on the microsphere surfaces were further modified to tert-amine, thioacetate, and carboxyl groups via thiol–epoxy click reactions. The morphologies of the porous microspheres were investigated using a scanning electron microscope (SEM). When the content of PEG was 35 wt%, porous polymer microspheres with average diameters of ∼70 μm and highest porosities of 62.45% were obtained. Subsequently, diverse modified porous microspheres were used to adsorb copper ions that were dissolved in DMF. Among these as-prepared microspheres, the thioacetate-functionalized one exhibited the highest Cu2+ adsorption capacity (158 mg g−1) at room temperature. Exploration of its adsorption behaviors illustrated that the thioacetate-functionalized microspheres followed a chemically controlled monolayer adsorption mechanism. Our work presents a brand new reliable strategy for the synthesis and functionalization of non-degradable epoxy-containing porous microspheres, which can be used for the adsorption or removal of toxic metal ions (such as copper ions).

Thiol-yne click polymerization (TYCP) is one of the most significant synthetic techniques for artificial polymers, due to its simplicity, efficiency, and functionality tolerance. In nature, it is a classic nucleophilic addition reaction and a step-growth polymerization, which can be initiated or accelerated in the presence of free-radicals, amines, and transition metals, respectively. Its rate is greatly influenced by the structures (i.e., their electrophilicity and steric hindrance) of the used thiols and/or alkynes. With aliphatic monomers being used as feeding materials, the topological architectures (such as linear, branching, and cross-linked network, etc.) and available functional groups (such as hydroxyl, carboxyl, amino, and epoxy groups, and so on) can be facilely tailored via altering the chemical structure and feeding order. In contrast, for aromatic monomers, mono-addition occurs only during the process of thiol-yne click reaction, leading exclusively to linear poly(vinyl thioether)s. These sulfur-containing polymers synthesized by TYCP are promising to be widely utilized as high refractive index materials, photovoltaic materials, drug-delivery vehicles, biomaterials, and hybrid materials, etc.

Graphene oxide (GO) is highly attractive for catalysis because of its large specific surface area and rich chemical structures. However, it has generally been used as a catalyst carrier. Here, we designed a three-dimensional monolith of neat GO aerogel as a fixed-bed carbocatalyst used in the reaction of S → O acetyl migration for the synthesis of thiol compounds, showing the merits of ultrafast catalytic speed (5–8 h), high selectivity (100%), high yields (near 100%), easy isolation of products, and long-life recyclability (>18 times). Particularly, we achieved for the first time thiol compounds containing functional groups of halogen and hydroxyl, which cannot be synthesized using other currently reported catalysts. Control experiments demonstrated that the efficient catalysis mechanism is mainly attributed to the protonic functional groups, ultralarge size, and unpaired electrons of GO, as well as the “cage effect” at nanoscale confined spaces of aerogel cells.

Hyperbranched polymers (HPs) are highly branched three-dimensional (3D) macromolecules. Their globular and dendritic architectures endow them with unique structures and properties such as abundant functional groups, intramolecular cavities, low viscosity, and high solubility. HPs can be facilely synthesized via a one-pot polymerization of traditional small molecular monomers or emerging macromonomers. The great development in synthetic strategies, from click polymerization (i.e., copper-catalyzed azide-alkyne cycloaddition, metal-free azide-alkyne cycloaddition, strain-promoted azide-alkyne cycloaddition, thiol-ene/yne addition, Diels-Alder cycloaddition, Menschutkin reaction, and aza-Michael addition) to recently reported multicomponent reactions, gives rise to diverse HPs with desirable functional/hetero-functional groups and topologies such as segmented or sequential ones. Benefiting from tailorable structures and correspondingly special properties, the achieved HPs have been widely applied in various fields such as light-emitting materials, nanoscience and technology, supramolecular chemistry, biomaterials, hybrid materials and composites, coatings, adhesives, and modifiers. In this review, we mainly focus on the progress in the structural control, synthesis, functionalization, and potential applications of both conventional and segmented HPs reported over the last decade.

We describe a novel triethylamine catalyzed S → O acetyl migration reaction for yielding thiol compounds under mild conditions through the formation of a transitional 5-membered ring. A series of epoxy compounds have been transformed into their thiol counterparts which could be used for construction of topological and functional sulfur-containing polymers. The one-pot two-step processes including the S → O acetyl migration and the following thiol-click reactions avoided separation of thiol intermediates. Applying these processes on a new-type latent polythiols overcomes crosslinking problem usually met in preparation of multithiol compounds due to the formation of disulfide bonds.

This paper firstly revealed the electrophilic effect of thiol groups on thiol–yne polymerization. For this, we designed and synthesized five kinds of α-thiol-ω-alkynyl AB2 type intermediates with thiols with different electrophilicities. The thiol electrophilic effect can be assessed by chemical shift (δ) and measured directly by nuclear magnetic resonance (NMR) spectroscopy. As the evidence from gel permeation chromatography (GPC) and NMR tracking measurements shows, the polymerization rate and molecular weight (MW) were significantly enhanced as the thiol electrophilic effect reduced. On the contrary, with increasing electrophilicity of the thiol, the resultant degrees of branching (DBs) increased. The semiquantitative relation between reactive rate constant (k) and δ (or electrophilicity of thiol) can be expressed by k = 2.41–1.34δ. Therefore, important features of thiol–yne polymerization and HPTEs, such as rate constant (k), MW, DB, etc., can be roughly estimated in advance by the NMR measurement of the thiol's electrophilic effect.

In this work, a novel initiator bearing heptaphenyl polyhedral oligomeric silsesquioxane (POSS) was synthesized via the copper-catalyzed Huisgen 1,3-cycloaddition (i.e., click chemistry). With this initiator, the atom transfer radical polymerization (ATRP) of N -isopropylacrylamide (NIPAAm) was carried out to afford the POSS-capped PNIPAAm. The organic–inorganic amphiphiles were characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Atomic force microscopy (AFM) showed that the POSS-capped PNIPAAm amphiphiles in bulk displayed microphase-separated morphologies. In aqueous solutions, the POSS-capped PNIPAAm amphiphiles were self-assembled into micelle-like aggregates as evidenced by dynamic light scattering (DLS) and transmission election microscopy (TEM). It was found that the sizes of the self-organized nanoobjects decreased with increasing the lengths of PNIPAAm chains. By means of UV–vis spectroscopy, the lower critical solution temperature (LCST) behavior of the organic–inorganic amphiphiles in aqueous solution was investigated and the LCSTs of the organic–inorganic amphiphiles decreased with increasing the percentage of POSS termini. It is noted that the self-assembly behavior of the POSS-capped PNIPAAm in aqueous solutions exerted the significant restriction on the macromolecular conformation alteration of PNIPAAm chains while the coil-to-globule collapse occurred.

Poly(ethylene oxide)-grafted poly(N-isopropylacrylamide) networks (PNIPAAm-g-PEO) were prepared via the reversible addition–fragmentation chain transfer polymerization (RAFT) of N-isopropylacrylamide with trithiocarbonate-terminated poly(ethylene oxide) and N,N′-methylenebisacrylamide as the chain transfer agent and the crosslinking agent, respectively. It was found that the PNIPAAm-g-PEO copolymer networks were microphase-separated and that PEO microdomains were dispersed in the PNIPAAm matrix. The hydrogel behavior of the PNIPAAm-g-PEO networks was investigated using swelling, deswelling and reswelling tests. The PNIPAAm-g-PEO hydrogels displayed faster responses to external temperature changes than did the control PNIPAAm hydrogel.

In this work, the synthesis of 3-methacryloxypropylheptaphenyl POSS, a new POSS macromer (denoted MA-POSS) is reported. The POSS macromer is used to synthesize PEO-b-P(MA-POSS)-b-PNIPAAm triblock copolymers via sequential atom transfer radical polymerization (ATRP). The organic-inorganic, amphiphilic and thermoresponsive ABC triblock copolymers are characterized by means of nuclear magnetic resonance spectroscopy (NMR) and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) and atomic force microscopy (AFM) show that the hybrid ABC triblock copolymers are microphase-separated in bulk. Cloud point measurements show that the effect of the hydrophiphilic block (i.e. PEO) on the LCSTs is more pronounced than the hydrophobic block (i.e. P(MA-POSS)). Both transmission electron microscopy (TEM) and dynamic light scattering (DLS) show that all the triblock copolymers can be self-organized into micellar aggregates in aqueous solutions. The sizes of the micellar aggregates can be modulated by changing the temperature. The temperature-tunable self-assembly behavior is interpreted using a combination of the highly hydrophobicity of P(MA-POSS), the water-solubility of PEO and the thermoresponsive property of PNIPAAm in the triblock copolymers.

Hyperbranched polymers (HPs) are highly branched three-dimensional (3D) macromolecules. Their globular and dendritic architectures endow them with unique structures and properties such as abundant functional groups, intramolecular cavities, low viscosity, and high solubility. HPs can be facilely synthesized via a one-pot polymerization of traditional small molecular monomers or emerging macromonomers. The great development in synthetic strategies, from click polymerization (i.e., copper-catalyzed azide–alkyne cycloaddition, metal-free azide–alkyne cycloaddition, strain-promoted azide–alkyne cycloaddition, thiol–ene/yne addition, Diels–Alder cycloaddition, Menschutkin reaction, and aza-Michael addition) to recently reported multicomponent reactions, gives rise to diverse HPs with desirable functional/hetero-functional groups and topologies such as segmented or sequential ones. Benefiting from tailorable structures and correspondingly special properties, the achieved HPs have been widely applied in various fields such as light-emitting materials, nanoscience and technology, supramolecular chemistry, biomaterials, hybrid materials and composites, coatings, adhesives, and modifiers. In this review, we mainly focus on the progress in the structural control, synthesis, functionalization, and potential applications of both conventional and segmented HPs reported over the last decade.

A series of water soluble octa-functionalized POSSs were facilely synthesized via thiol-ene and Menschutkin click chemistry. Among them, octa-alkynyl POSS further reacted with azide-terminal alkyl long chains, resulting in a well-defined, amphiphilic octopus-like POSS. For the first time it was used for host-guest encapsulation and it exhibited an ultrahigh loading capability.

Sequence-controlled polymers (SCPs) such as DNA and proteins play an important role in biology. Many efforts have been devoted to synthesize SCPs in the past half a century. However, to our knowledge, the artificial sequences containing independently functional groups have never been reported. Here, we present a facile and scalable approach based on radical-initiated step-growth polymerization to synthesize sequence-controlled functional polymers (SCFPs) with various topologies, covering from linear to random and hyperbranched polymers. The functional groups, such as OH/NH2, OH/COOH, and NH2/N3, alternately arranged along the chain, which were further selectively functionalized to achieve DNA-mimic and hetero-multifunctional SCPs. This user-friendly strategy exhibits advantages of commercially available monomers, catalyst-free process, fast reaction, high yield and water solvent, opening a general approach to facile and scalable synthesis of SCFPs.

A novel kind of amphiphilic hyperbranched polymer (AHP), poly(2-(dimethylamino)ethyl methacrylate)-co-polystyrene (HPTAM-co-PS), was synthesized via the combination of reversible addition–fragmentation chain-transfer polymerization and self-condensing vinyl polymerization (RAFT-SCVP). HPTAM-co-PS was functionalized via the highly efficient Menschutkin click reaction, resulting in hyperbranched poly(propargyl quaternary ammonium methacrylate)-co-polystyrene (HPPrAM-co-PS) with a hydrophilic quaternary ammonium salt core and hydrophobic PS shell. The average numbers of dye molecules trapped by each molecule of HPPrAM-co-PS (24.2 kDa) were 24.1 for methyl orange (MO), 22.0 for fluorescein sodium (FS), 24.2 for rose bengal (RB), and 238.4 for Congo red (CR). The polymer–dye complexes show excellent colouring effects for both PS and poly(styrene-b-butadiene-b-styrene) (SBS) membranes; the colour of the membrane containing AHP is very stable and uniform. Our work opens an avenue for the design of efficient dye-colouring additives and for the application of hyperbranched polymers in the field of polymer colouring.