The intrinsic conflicts between mechanical performances and processability are main challenges to develop cost‐effective impact‐resistant materials from polymers and their composites. Herein, polyhedral oligomeric silsesquioxanes (POSSs) are integrated as side chains to the polymer backbones. The one‐dimension (1D) rigid topology imposes strong space confinements to realize synergistic interactions among POSS units, reinforcing the correlations among polymer chains. The afforded composites demonstrate unprecedented mechanical properties with ultra‐stretchability, high rate‐dependent strength, superior impact‐resistant capacity as well as feasible processability/recoverability. The hierarchical structures of the hybrid polymers enable the co‐existence of multiple dynamic relaxations that are responsible for fast energy dissipation and high mechanical strengths. The effective synergistic correlation strategy paves a new pathway for the design of advanced cluster‐based materials.

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Three-dimensional (3D) printing has had a large impact on various fields, with fused deposition modeling (FDM) being the most versatile and cost-effective 3D printing technology. However, FDM often requires sacrificial support structures, which significantly complicates the processing and increase the cost. Furthermore, poor layer-to-layer adhesion greatly affects the mechanical stability of 3D-printed objects. Here, we present a new Print-Healing strategy to address the aforementioned challenges. A polymer ink (Cu-DOU-CPU) with synergetic triple dynamic bonds was developed to have excellent printability and room-temperature self-healing ability. Objects with various shapes were printed using a simple compact 3D printer, and readily assembled into large sophisticated architectures via self-healing. Triple dynamic bonds induce strong binding between layers. Additionally, damaged printed objects can spontaneously heal, which significantly elongates their service life. This work paves a simple and powerful way to solve the key bottlenecks in FDM 3D printing, and will have diverse applications.

Acting as soft-nanoparticles, series of microgels are microemulsion polymerized and investigated for their dynamics in the melt state. Each series is kept at the same average number of repeating units between crosslinking points, in short, the crosslinking degree. The relaxation time increases at the 30th power of their diameters or 10th power of their molecular weights or volume and then diverges upon approaching the critical diameter. Our proposed equation describes their relaxation time as a function of diameter and crosslinking degree and unifies both our and literature data. Soft-nanoparticles larger than the critical diameter cannot relax in the melt state within the experimental limits. This may serve as the boundary between thermal molecular or macromolecular domains and the athermal colloidal domain. This critical diameter obeys 1/3 power of the crosslinking degree. This agrees with the Hertzian contact model and the stress originates from elastic deformation. This scaling also implies that the boundary is where SNPs contain a constant number of crosslinking points, around 200. Our equation foresees that for the same molecular weight while changing the topology from linear chains to more and more elastic soft-nanoparticles the relaxation time should first decrease and then increase to infinity. The initial decrease is more dramatic for lower molecular weights.

Telechelic associating polymers, TAPs, have numerous industrial applications and are typically evaluated at different concentrations and by their shear viscosity. Here, in situ UV irradiation is added to a dripping-onto-substrate rheometer. TAPs with telechelic coumarin end groups would undergo UV-induced coupling, leading to additional step polymerization of TAPs. This enables us to in situ increase the molecular weight of TAPs without changing concentrations. Their extensional rheology is studied from the recorded pinching process. Extensional viscosities in the elastocapillary state are 10 times higher than those in the viscocapillary state, indicating significant chain stretching. With increasing molecular weights or degrees of coupling, the evolution of capillarity, inertia, viscous, and elastic behaviors is captured by the dimensionless Ohnesorge number and intrinsic Deborah number. The narrow region of a beads-on-a-string structure is also mapped experimentally. Using telechelic associating and coupling polymers as a model system, we have illustrated the evolution of their extensional behaviors as the molecular weight increases.

Rheological measurements typically require at least 20–50 mg of sample. We set up a miniaturized sliding-plates shear rheometer (mgRheo) that requires only 2 mg sample or even less. We designed a flexure-based force-sensing device that could measure force ranging from the micronewton to millinewton scale, e.g., 40 μN–400 mN for one particular spring constant. The setup was strain-controlled by a piezostage and could perform standard rheological tests such as small amplitude oscillatory shear, step strain, and stress relaxation. The accuracy and consistencies were evaluated on polydimethylsiloxane viscoelastic standard, entangled poly(hexyl methacrylate), and polystyrene. The obtained phase angles quantitatively agreed with those from commercial rheometers. The exact values of the modulus are prone to the overfilling of the sample. The storage G′ and loss G″ moduli from the mgRheo were systematically higher than those from commercial rheometers (i.e., within 5% with careful trimming or 30% with excessive overfilling). Between 102 and 106 Pa, G′ and G″ were in good agreement with commercial rheometers. Such a setup allowed for general rheometric characterizations, especially obtaining linear viscoelasticity on soft matters that are synthetically difficult to obtain in a large quantity.

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