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To realize intelligent and low-cost protective materials, the development of compounds with smart stress-responsive properties and self-healing abilities over a wide temperature range is a major research goal. In this study, a series of impact hardening polymers (IHPs) with stress-responsive properties and self-healing ability in low temperature were synthesized via the condensation copolymerization of silicone polymers with various chain lengths and boron contents. The results of rheological analysis indicate that the IHPs have self-healing ability at low temperatures (healing times of less than 30 h and healing efficiencies better than 80% at −25 °C). Moreover, the relative shear stiffening effect (RSTe), which describes the stress-responsive ability of the IHP, exceeded 2000. In addition, the self-healing mechanism of IHP was investigated by Fourier transform infrared spectroscopy microscopy and pulsed 1H-NMR measurements. The results suggested that reversible dynamic cross-linking arising from the boron compound and the reduction in the threshold entanglement density owing to the longer length of the flexible polymeric backbone is crucial to impart low-temperature self-healing ability and stress-responsive properties to IHP.

Adsorptive membranes offer an effective mode to remove heavy metal ions from contaminated water, due to the synergies made possible by low-cost, high-affinity adsorbents and highly scalable filtration in one system. However, the development of adsorptive membranes is hampered by their instability in the aqueous phase and low binding affinity with a broad spectrum of heavy metals in a reasonable flux. Herein, a regenerated cellulose support membrane is strongly grafted with stable and covalent-bonded polyelectrolyte active layers synthesized by a reactive layer-by-layer (LBL) assembly method. The LBL assembled layers have been successfully tested by scanning electron microscopy, Fourier-transform infrared spectroscopy and X-ray photo-electron spectroscopy. The covalent bonding provides the membrane with long-term stability and a tunable water flux compared to a membrane assembled by electrostatic bonding. The maximum adsorption capacity of the membrane active layers can reach up to 194 mg/g, showing more efficient adsorption at lower heavy metal concentration and higher pH value of feed solution. The membrane can remove multiple ions, such as Cu, Pb, and Cd, by adsorption and is easy to be regenerated and recovered. The strong covalent bonding can extend the membrane lifetime in water purification to remove multiple heavy metals at high efficiency.

Nonspherical colloidal particles with various geometries and different compositions have attracted tremendous attention and been widely researched. The preparation of polymer colloidal particles with controlled shapes by seeded polymerization is recognized as the most promising technique owing to the precise control of various morphologies and using non-cross-linked seed particles are of particular interest. Seeds particles derived from natural biopolymers are seldom applied. Hence, non-cross-linked starch-based seed could be used to fabricate the anisotropic particles by soap-free seed polymerization. Non-cross-linked starch-based seed particles were prepared by a nanoprecipitation method. Starch/polystyrene composite colloidal particles with shape-tunable were fabricated by soap-free seeded polymerization using starch-based seed. The effect of the polymerization time, monomer feed ratio and seed type were investigated. The seed particles with a single- or multi-hole structure were obtained after swelling with styrene. The resulting particles including golf-like, raspberry-like, octahedron-like and snowman-like structures, was fabricated on the polymerization process. This study firstly reports that the morphology of composite particles from golf-like to snowman-like at high monomer feed ratio using starch-based seed. At low monomer feed ratio, raspberry-like particles were obtained by surface nucleation increasing process. In addition, seed type also effect the morphology of composite particles.

A series of chemically cross-linked microgel composite hydrogels (MCH gels) with excellent toughness and stretchability were prepared using core–shell polymer microspheres as cross-linking junctions. In our strategy, MCH gels are obtained by connecting microspheres with polyacrylamide (PAAm) chains chemically grafted onto their surfaces, where an organic cross-linking agent is completely unnecessary. The mechanical behavior of the MCH gels was analyzed, and superresolution fluorescence microscopy and scanning electron microscopy were used to investigate their toughening mechanism. The results indicated that the homogeneous network structure resulting from the good compatibility between the core–shell microspheres and matrix was an important reason for the excellent toughness of the MCH gels. In addition to interactions among H bonds in the grafted PAAm chains, reversible deformation of the core–shell microspheres acting as cross-linking junctions, which arises from the flexibility of the microspheres, and the effect of cavitation between the microspheres and matrix could also effectively dissipate energy during deformation of the MCH gels.

We study biosourced core-shell particles with a starch-based core and thermo-responsive polymer brush shell using surface-initiated single-electron transfer living radical polymerization (SI-SET-LRP) as a Pickering stabilizer. The shell endows the Pickering stabilizer with reversible emulsification/demulsification of oil and water properties. The initiator attached to the starch-based nanosphere (Br-SNP) core particle was first fabricated using the precipitation method. Subsequently, dense poly( N-isopropylacrylamide) (PNIPAM) brush graft-modified starch-based nanoparticles (SNP- g-PNIPAM) were obtained via the SI-SET-LRP process. Interfacial properties of the resultant particles were analyzed by interfacial tensiometer measurements, as were the effects of the grafted polymer chain length and temperature on the interfacial activity. Pickering emulsion was obtained using SNP- g-PNIPAM particles as the stabilizer. The effect of the concentration of the Pickering stabilizer on the size of emulsion droplets was analyzed. The emulsification/demulsification process of the Pickering emulsion can be reversed and easily repeated by changing the temperature.

We developed tough, rapid-recovery composite hydrogels that are fabricated via core–shell microgel covalent bonding and Fe3+ dynamic metal coordination cross-linking. First, core–shell microgels are used as cross-linking agents and initiators to prepare homogeneous hydrogel networks with rapid recovery in the absence of an organic cross-linking agent. The toughness and recoverability of the composite hydrogels can be improved by adding the dynamic reversibility of ionic cross-linking. Owing to the synergistic effect of microgel covalent bonding, Fe3+ coordination cross-linking, and H-bond cross-linking, the multi-cross-linked composite hydrogels exhibit excellent toughness and a fast recovery rate. These characteristics demonstrate that the dynamic reversibility of the ionic cross-linking can significantly improve the toughness and recoverability of the hydrogels. In addition, the core–shell microgels play a key role in toughening the hydrogels and accelerating their recovery by transferring stress to grafted polymer chains and homogenizing the hydrogel network.

The convenient synthesis of core-shell nanoparticles containing degradable components is very desirable given the potential applications of such nanoparticles in biomaterials. A facile approach for producing monodisperse starch-polystyrene nanocomposites with well-defined core-shell structures in the absence of a surfactant was developed. The initially-formed Pickering emulsions underwent conversion into seeded emulsions during the polymerization, wherein the amphiphilic starch-based nanospheres (SNPs) serve as stabilizer and seed. A possible mechanism for this transition was explored based on the morphology and size variations of the emulsion droplets and the resultant nanospheres. The effects of the monomer concentration, SNP content and size, and pH on the core-shell nanospheres were investigated. With increasing monomer concentration, the core size of the particles remained almost unchanged, while the shell layer thickness increased almost linearly. The size of the core-shell nanospheres can be regulated by adjusting the pH and the SNP content and size.

Understanding the interfacial activity of polysaccharide nanoparticles adsorbed at oil–water interfaces is essential and important for the application of these nanoparticles as Pickering stabilizers. The interfacial properties of starch-based nanospheres (SNPs) at the interface of an n-hexane–water system were investigated by monitoring the interfacial tension at different bulk concentrations. The three-phase contact angle (θ) and the adsorption energy (ΔE) increased with increasing size and degree of substitution with octenyl succinic groups (OSA) in the particles. Compared with the OSA-modified starch (OSA-S) macromolecule, the SNPs effectively reduced the interfacial tension of the n-hexane–water system at a relatively higher concentration. These results and the method reported herein are useful for selecting and preparing polysaccharide nanoparticles as Pickering stabilizers for oil–water emulsions.

Biodegradable polymer nanocomposites with bioresource starch-based nanoparticles (SNPs) as reinforcing fillers for polycaprolactone (PCL) were prepared by melt blending. Scanning electron microscopy observation revealed that SNPs as spherical particles were evenly dispersed in the PCL matrix without any aggregation even with the content of SNPs increasing to 10wt% in the nanocomposite. Consequently, the rheological performances of PCL have been improved efficaciously after incorporation with SNPs as well as mechanical properties, especially with a percolation network structure of SNPs in the PCL matrix formed. In addition, the enzymatic hydrolysis experiments showed a more interesting behavior that the hydrolysis rates had been accelerated apparently in the nanocomposites than that in the neat PCL as observed. Such high performance nanocomposites may have great potential in expanding the utilization of starch from sustainable resources and the practical application of PCL-based biodegradable materials.