Two-Way Conversion between Hard and Soft Properties of Semicrystalline Cross-Linked Polymer

A semicrystalline cross-linked polymer exhibiting two-way conversion between totally different mechanical properties was obtained. Furyl-telechelic poly(1,4-butylene succinate-co-1,3-propylene succinate) prepolymer (PBPSF2) was prepared and polymerized with tris-maleimide linker (M3) by the Diels−Alder (DA) reaction in the bulk state. The DA reactions with M3 above and below the melting temperature of PBPSF2 gave network polymers with relatively soft and hard properties, respectively, though the degrees of crystallinity of them were very similar. The large difference in mechanical properties was attributed to the difference in size of crystallites. By combining the two dynamic processes of melt−recrystallization and depolymerization−repolymerization, we can freely convert the PBPSF2 + M3 system back and forth between hard and soft materials

Computer-Aided Design of Copolymers with Controlled Comonomer Distributions

The sequence distribution of comonomer units in copolymers drastically affects the properties of the polymeric materials; the prediction and control of the sequence distribution are challenging when there is a significant reactivity difference among the comonomers. In this study, we established a computer-aided design (CAD) framework to rationally design and synthesize copolymers with the desired comonomer distributions by using the scheduled comonomer addition strategy. We developed a simulation method that predicted the living copolymerization process with the scheduled addition of comonomers into the reaction mixture. The simulation quantitatively reproduced the real-world copolymerization results. The comonomer addition schedule was designed for a given target comonomer distribution with the aid of simulation; this process was then used to experimentally produce the copolymer. With this method, we successfully synthesized random copolymers via the ring-opening metathesis copolymerization of two norbornene derivatives with an approximately 25-fold difference in their propagation rate constant; this was impossible with a simple batch addition strategy. Copolymers with much more complicated comonomer distributions could also be designed. Our CAD framework will promote the development of a vast diversity of polymers with various properties, even from a limited set of monomers

Computer-Aided Design of Copolymers with Controlled Comonomer Distributions

The sequence distribution of comonomer units in copolymers drastically affects the properties of the polymeric materials; the prediction and control of the sequence distribution are challenging when there is a significant reactivity difference among the comonomers. In this study, we established a computer-aided design (CAD) framework to rationally design and synthesize copolymers with the desired comonomer distributions by using the scheduled comonomer addition strategy. We developed a simulation method that predicted the living copolymerization process with the scheduled addition of comonomers into the reaction mixture. The simulation quantitatively reproduced the real-world copolymerization results. The comonomer addition schedule was designed for a given target comonomer distribution with the aid of simulation; this process was then used to experimentally produce the copolymer. With this method, we successfully synthesized random copolymers via the ring-opening metathesis copolymerization of two norbornene derivatives with an approximately 25-fold difference in their propagation rate constant; this was impossible with a simple batch addition strategy. Copolymers with much more complicated comonomer distributions could also be designed. Our CAD framework will promote the development of a vast diversity of polymers with various properties, even from a limited set of monomers

Seawater-Assisted Self-Healing of Catechol Polymers via Hydrogen Bonding and Coordination Interactions

It is highly desirable to prevent crack formation in polymeric materials at an early stage and to extend their lifespan, particularly when repairs to these materials would be difficult for humans. Here, we designed and synthesized catechol-functionalized polymers that can self-heal in seawater through hydrogen bonding and coordination. These bioinspired acrylate polymers are originally viscous materials, but after coordination with environmentally safe, common metal cations in seawater, namely, Ca²⁺ and Mg²⁺, the mechanical properties of the polymers were greatly enhanced from viscous to tough, hard materials. Reduced swelling in seawater compared with deionized water owing to the higher osmotic pressure resulted in greater toughness (∼5 MPa) and self-healing efficiencies (∼80%)

Computer-Aided Design of Copolymers with Controlled Comonomer Distributions

The sequence distribution of comonomer units in copolymers drastically affects the properties of the polymeric materials; the prediction and control of the sequence distribution are challenging when there is a significant reactivity difference among the comonomers. In this study, we established a computer-aided design (CAD) framework to rationally design and synthesize copolymers with the desired comonomer distributions by using the scheduled comonomer addition strategy. We developed a simulation method that predicted the living copolymerization process with the scheduled addition of comonomers into the reaction mixture. The simulation quantitatively reproduced the real-world copolymerization results. The comonomer addition schedule was designed for a given target comonomer distribution with the aid of simulation; this process was then used to experimentally produce the copolymer. With this method, we successfully synthesized random copolymers via the ring-opening metathesis copolymerization of two norbornene derivatives with an approximately 25-fold difference in their propagation rate constant; this was impossible with a simple batch addition strategy. Copolymers with much more complicated comonomer distributions could also be designed. Our CAD framework will promote the development of a vast diversity of polymers with various properties, even from a limited set of monomers

Morphology-Retaining Carbonization of Honeycomb-Patterned Hyperbranched Poly(phenylene vinylene) Film

Ordered porous materials are of great technological interest for use as separation, catalysis, adsorbents, and electronic devices. We report here a fabrication of honeycomb-patterned porous films from fluorescent hyperbranched poly(phenylene vinylene) (hypPPV) by breath figure method and the thermal conversion of this film to macroporous carbon. This hexagonal porous film is very thermally stable and retained its structure at up to >600 °C. After the heating, carbonization of hypPPV occurred, and black porous carbon film was obtained. Additionally, because π-conjugated hypPPV has many vinylene moieties at its terminus, the photo-cross-linking reaction easily proceeds without the collapse of the honeycomb structures. This cross-linking reaction rendered the honeycomb films completely insoluble in organic solvents. Because of the provided high thermal and chemical stability, the honeycomb films are a new class of microstructured materials that is promising for many applications such as durable electroluminescence devices, bandgap materials, adsorbents, electrodes, and solvent-resistant porous membranes

Tunable Mechanical Properties in Microphase-Separated Thermoplastic Elastomers via Metal–Ligand Coordination

Inspired by the structure of tough biological tissues of mussel byssus cuticles, the incorporation of weak reversible bonds in multiphase thermoplastic elastomers (TPEs) has shown promise for enhancing mechanical performance. However, the effects of the reversible bond distribution on the mechanical properties of TPEs warrant further investigation. Here, a novel design strategy was proposed and demonstrated to improve the toughness of TPEs by introducing metal–ligand coordination bonds in all phases of a TPE with a microphase-separated structure. An ABA-type triblock copolymer was designed, with varying ligand density in the A and B blocks. Based on the immiscibility of two blocks, the A blocks aggregated to form hard phases with a high density of metal–ligand bonds, dispersed within the soft matrix phase consisting of the B block and spare metal–ligand bonds. Metal–ligand coordination bonds in the hard and soft phases, as well as at their interface, played crucial roles in the dynamic mechanical properties of the TPE. Furthermore, the mechanical properties of this TPE could be easily and extensively adjusted by manipulating the parameters associated with the metal–ligand coordination bonds. Our design strategy provides insights into the relationship between metal–ligand coordination bonds and multiphase structures and their combined effects on the bulk mechanical properties of TPEs

Computer-Aided Design of Copolymers with Controlled Comonomer Distributions

The sequence distribution of comonomer units in copolymers drastically affects the properties of the polymeric materials; the prediction and control of the sequence distribution are challenging when there is a significant reactivity difference among the comonomers. In this study, we established a computer-aided design (CAD) framework to rationally design and synthesize copolymers with the desired comonomer distributions by using the scheduled comonomer addition strategy. We developed a simulation method that predicted the living copolymerization process with the scheduled addition of comonomers into the reaction mixture. The simulation quantitatively reproduced the real-world copolymerization results. The comonomer addition schedule was designed for a given target comonomer distribution with the aid of simulation; this process was then used to experimentally produce the copolymer. With this method, we successfully synthesized random copolymers via the ring-opening metathesis copolymerization of two norbornene derivatives with an approximately 25-fold difference in their propagation rate constant; this was impossible with a simple batch addition strategy. Copolymers with much more complicated comonomer distributions could also be designed. Our CAD framework will promote the development of a vast diversity of polymers with various properties, even from a limited set of monomers

Antioxidant and Adsorption Properties of Bioinspired Phenolic Polymers: A Comparative Study of Catechol and Gallol

Polyphenols, which by the Quideau definition are plant-derived chemicals with two or more phenolic groups, have attracted interest because of their antioxidant activity, adsorption on universal substrates, and biocompatibility. Most polyphenols include gallol groups in their chemical structures, which has inspired us to synthesize gallol-functionalized polymers. We report the reversible addition–fragmentation chain transfer polymerization of 3,4,5-trimethoxystyrene using cyanomethyl dodecyl trithiocarbonate as the chain transfer agent. This method produces well-defined polymers with a wide range of molecular weight (from 5.4 to 53.4 kg mol^–1) and low polydispersity index (<i>M</i>_w/<i>M</i>_n < 1.3). Subsequent demethylation of poly­(3,4,5-trimethoxystyrene) (PTMS) yields poly­(3,4,5-trihydroxystyrene) (polyvinylgallol, PVGal). These newly synthesized polymers exhibit greater antioxidant activities than widely used catechol-functionalized polymers based on the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), 2,2′-azinobis­(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and oxygen radical absorbance capacity (ORAC) methods. Also, PVGal showed better adsorption properties on metals and SiO₂ substrates than those of the other phenolic polymers. Given these high antioxidant and adsorption properties, the effective use of gallol-funcationalized polymers in biomaterials is expected

Polymers with Multishape Memory Controlled by Local Glass Transition Temperature

A multishape memory polymer with flexible design capabilities is fabricated by a very simple method. Local glass transition temperatures of a loosely cross-linked polymer film are changed by immersing sections of the film in a cross-linker solution with a different concentration. Each section memorizes a temporary shape, which recovers its permanent shape at a different recovery temperature depending on the local glass transition temperature. As a base polymer, we chose a network polymer prepared by a Diels–Alder reaction between poly­(2,5-furandimethylene succinate) (PFS) and 1,8-bis-maleimidotriethyleneglycol (M₂). Quintuple shape memory behavior was demonstrated by a PFS/M film with four sections with distinct glass transition temperatures. The number of temporary shapes was determined by the number of different M₂ solutions. Furthermore, owing to the reversibility of the Diels–Alder reaction, the permanent shape was rewritable