Themed collection Polymer Networks

Yukikazu Takeoka introduces the Soft Matter and Polymer Chemistry cross-journal themed collection on polymer networks.

By classifying stretchable ionic materials into three types of components (ionic conductors, ionic semiconductors, and ionic insulators), we summarized materials development in stretchable iontronics in terms of molecular interactions.

A newly designed azo-PI, without pre-stretching or polarized-light irradiation, exhibits reversible bending behaviors under alternate UV and visible light irradiation, providing a facile route to deformable 2D/3D structure actuators.

We report a thermoresponsive ionogel with switchable adhesion both in air and aqueous environments, which can be utilized for the underwater on demand capture and release.

Ultrahigh thermoresistant polybenzimidazole films with uniform pores and hard craters on the surface were prepared by a silica template method. The pore and crater formation enhanced elongation and Young's modulus.

A method for lowering the activation energy of melting while improving the mechanical robustness of an elastomer was achieved using bottlebrush topologies. This system has the potential to realize self-healing materials with enhanced processability.

The real-time visualization via high-speed atomic force microscopy revealed that single microgel exhibit heterogeneous degradation behavior.

DLS measurements revealed that temperature-responsive gels prepared by ATRP have more homogeneous networks than those by free radical polymerization. The standard deviation of the scattered intensity is used to quantify the network inhomogeneity.

Environmentally responsive hydrogel composites embedded with submicron-sized spherical silica particles for the modulation of the mid-infrared radiation derived from the Bragg reflection are therein designed for personalized body thermoregulation.

We propose a strategy based on athermal photo-welding to construct 3D actuators assembled by azobenzene-containing linear liquid crystal polymers with different orientations, which demonstrate diverse deformations of curling, winding, and unwinding.

The effect of ionic liquid and monomer structures on the mechanical properties of ultrahigh molecular weight ion gels was investigated.

A bio-printable hydrogel of regenerated silk fibroin with high-molecular-weight was prepared from its aqueous solution with the help of urea involvement, and the gelation process and properties of the hydrogel was investigated.

Using RheoSAXS, the change in microstructure of PMMA-PnBA-PMMA triblock gels in 2-ethyl-1-hexanol subjected to oscillatory shear and temperature has been characterized.

The wearable shape memory multifunctional sensor array is capable of sensing both direction and quantity of bending displacement and velocity.

pH-regulated release of antibiotics is achieved by conjugation with the hydrogel matrix through the reversible imine bond.

Molecular architecture of nanogel particle.

TetraPEG hydrogels cross-linked via both boronic acid ester and acylhydrazone dynamic covalent bonds were developed. Adjustment of the fraction of each type of cross-link allows the fine-tuning of hydrogel behavior between self-repair and stability.

In chaotropic solution, the different lower critical solution temperature (LCST) increments of two structural isomers, namely, poly(N-isopropylacrylamide) (PNIPAAm) and poly(2-isopropyl-2-oxazoline) (PiPOx), is studied.

This work utilizes a combined effort of experiment and theory to report a new mechanism and scaling law to account for extreme toughening of diverse soft materials.

The effect of crosslinker content and core size on the interfacial self-assembly of batch-type PNIPAM@SiO₂ core–shell particles was studied, revealing parameter windows for chain phases, rhomboid packing and stable d = 448 nm non-close packed cores.

Design strategies of phosphonic acid polymers established advanced ion gels with high ionic conductivity, mechanical strength, and self-healing ability via a configurable balance of ionic and hydrogen bonding interactions at the molecular level.

Small structural changes to side chain groups have large consequences to the structures and dynamics of corresponding polysiloxane-based ionomers.

The simultaneous use of metal Lewis acids and photo-radical generators for dithioesters, which are the common dormant species for cationic and radical polymerization, made it possible to convert a cationic species into a radical by photoirradiation.

The effects of monomer arrangement and composition for star-shaped polymers composed of N-isopropylacrylamide and N,N-dimethylacrylamide on the shrinkage behavior of the gels is studied, to increase their shrinkage rates without reducing the network densities of the gels.

The synergetic effect of the movable crosslinking and the hydrogen bonds in γCDMe(x)PU contributed to the simultaneous increase in the mechanical properties such as Young’s modulus and toughness.

Time and strain effects on stress are not separable in supramolecular gels utilizing host–guest interactions in contrast to a dual cross-link gel with covalent and transient cross-links in which the separability was validated by the same assessment.

This work utilizes in situ crosslinked dynamic networks to show differences in stress-relaxation behavior depending on the bond strength of the metal–ligand crosslinker used.

Bio-based hydrogel films are fabricated by reacting a glycerol ethoxylate-based triazide and an isosorbide-based dialkyne via Cu(I)-catalyzed photo-click reaction. These materials are suitable candidates for the delivery of therapeutic molecules.

This work probes the mechanical strength of composite hydrogels as the assembly size scale of the hydrophobic secondary phase transitions across the elastofracture length.

Using Brownian dynamics simulations, we studied the mechanical properties of tetra-gel-type networks with varying arm length contrast of prepolymers to modulate the number of double linkages.

Biodegradable double network (DN) gels with remarkably high mechanical strength and toughness were synthesised. The biodegradable DN gels can be potentially applied in biomedical applications such as cartilage regeneration.

In situ oxidative polymerization of polydopamine in a hydrogel matrix enables tunable photothermal actuation of a hydrogel actuator.

Structural changes and mechanical responses of a model bottlebrush elastomer with a controlled network structure were investigated by small-angle X-ray scattering coupled with uniaxial tensile testing.

Triply interpenetrated networks were made with a unique dynamic linker in each network. The linkers were hydrogen bonds, boronic esters and Diels–Alder adducts. Triply dynamic materials had superior properties compared to doubly dynamic analogues.

A smart gel material exhibiting a simultaneous change in mechanical properties and photoluminescence is developed.

The temperature-responsive core–shell microgels comprising PMPC core and side-chain oligo(ethylene glycol) polymer shell were prepared via inverse miniemulsion RAFT polymerization using a water-soluble emulsifier with RAFT agent terminus.

Needle-induced cavitation is performed on model end-linked gels to experimentally determine when soft solids will fail through either cavitation or fracture. Attention is also paid to when cavitation damages the network structure.

We investigated the effect of ion pairs on the structure of complex coacervate core hydrogels (C3Gs) using small-angle X-ray/neutron scattering. The ratio between ammonium and guanidinium groups modulates both structure and salt-responsiveness of C3Gs as stimuli-responsive materials.

Mechanochromic elastomers with different thermo- and mechano-responsive radical-type mechanophores are prepared and their sensitivity to heat and mechanical force is investigated.

A strain-stiffening seal is soft to accommodate installation but stiff to block fluid flow. Leak by elastic deformation or rupture? We construct diagrams in which the two modes of leak are demarcated.

Biodegradable disulfide-crosslinked hydrogels were constructed via the visible light triggered thiol–disulfide exchange reaction under mild gelation conditions, and the hydrogel coatings could be rapidly self-healed in 10 min under ambient conditions.

D-Phenylalanine-based (DPFEG) hydrogel co-assembled with GO and its handedness reversal induced the selective delivery of chiral anticancer drugs under IR irradiation for tumor therapy.

We describe a strategy to improve information security by combining shape morphing and patterned fluorescence in a bilayer hydrogel. The information concealed in the hydrogel becomes readable after shape recovery and under UV light irradiation.

Vitrimers, dynamic polymer networks with topology conserving exchange reactions, can lead to unusual evolution of the melting temperature and crystal structure of ethylene networks.