Size-Controllable, Single-Step, and Scalable Synthesis of Hollow Polymer Nanoparticles

Bioactive polymers: A comprehensive review on bone grafting biomaterials

The application of bone grafting materials in bone tissue engineering is paramount for treating severe bone defects. In this comprehensive review, we explore the significance and novelty of utilizing bioactive polymers as grafts for successful bone repair. Unlike metals and ceramics, polymers offer inherent biodegradability and biocompatibility, mimicking the native extracellular matrix of bone. While these polymeric micro-nano materials may face challenges such as mechanical strength, various fabrication techniques are available to overcome these shortcomings. Our study not only investigates diverse biopolymeric materials but also illuminates innovative fabrication methods, highlighting their importance in advancing bone tissue engineering.

Perforin-Mimicking Molecular Drillings Enable Macroporous Hollow Lignin Spheres for Performance-Configurable Materials

Despite the first observations that the perforin can punch holes in target cells for live/dead cycles in the human immune system over 110 years ago, emulating this behavior in materials science remains challenging. Here, a perforin-mimicking molecular drilling strategy is employed to engineer macroporous hollow lignin spheres as performance-configurable catalysts, adhesives, and gels. Using a toolbox of over 20 molecular compounds, the local curvature of amphiphilic lignin is modulated to generate macroporous spheres with hole sizes ranging from 0 to 100 nm. Multiscale control is precisely achieved through noncovalent assembly directing catalysis, synthesis, and polymerization. Exceptional performance mutations correlate with the changes in hole size, including an increase in catalytic efficiency from 50% to 100%, transition from nonstick synthetics to ultrastrong adhesives (adhesion ≈18.3 MPa, exceeding that of classic epoxies), and transformation of viscous sols to tough nanogels. Thus, this study provides a robust and versatile noncovalent route for mimicking perforin-induced structural variations in cells, representing a significant stride toward the exquisite orchestration of assemblies over multiple length scales.

Synthesis of V-notched half-open polymer microspheres via facile solvent-tuned self-assembly

Polymer microspheres with a special V-notched half-open architecture were synthesized in a mixed solvent of water/ethanol (1 : 1 v/v) at room temperature.

Hydrochannel-Containing Hydrophobic Polymers by Inverse Emulsion Polymerization for Moisture-Driven Actuators

Two physical properties in polymers, hydrophobic and water-absorptive, are known to be incompatible. However, human skin in nature has a hydrophobic surface and yet absorbs water throughout hydrophilic amino acid sequences in filaggrin, one of the abundant proteins in our outermost skin layer. Although present in nature, a hydrophilic path network in a hydrophobic polymer is difficult to synthesize because of poor wettability and immiscibility between the two types of materials. Herein, we introduce a novel method for the creation of a hydrophobic absorptive polymer (HPHG), which overcomes the inherent incompatibility by increasing hydrophobicity of reaction sites in hydrophilic monomers. The methacrylate structure in hydrophilic monomers successfully contributes to stabilize reverse emulsions, which consist of polyethyleneglycol (PEG) methacrylate and polyethyleneglycol (PEG) dimethacrylate, in a hydrophobic matrix of polymethylhydrosiloxane and divinylpolydimethylsiloxane (PDMS material sources). The HPHG film (with a 11 weight percent water content) shows water repellency having over 100° contact angle with a water droplet and yet is capable of absorbing water by 19.1 weight percent while maintaining decent hydrophobicity on the surface (78° water contact angle). We have successfully demonstrated a moisture-driven actuator by constructing a bilayer of HPHG and PDMS (or a textile), which is delamination-free and transforms into a curvature geometry by a preferential expansion of the HPHG layer. HPHG is applicable for soft robotics and smart actuators where a hydrophobic artificial skin is needed to protect the surface against hydrophilic invasions of undesirable substances such as metal ions, bacteria, or viruses but absorptive for desirable evaporation and mobility by water migration in the polymer matrix.

Cross-Linker-Controlled Ostwald Ripening in Emulsion Polymerization of Hollow Copolymer Nanoparticles

We propose a synthesis method for hollow copolymer nanoparticles, in which the size is controllable by the wettability of the materials designed by relative energy difference (RED). We investigated the influence of cross-linkers in RED and the hollow polymer nanoparticle synthesis. The size of the nanoparticles was characterized by scanning electron microscopy and transmission electron microscopy images. The diameter size of the hollow copolymer (styrene-co-methyl methacrylate) changes from 400 to 141 nm and the average core-vacancy sizes changes from 330 to 71 nm as increasing the feed ratio of the cross-linker, divinyl benzene, from 0.07 to 0.43. Cross-linkers in polymerization precipitates a polymerization reaction to produce seed copolymer particles quickly. The seed copolymer is a more transferrable medium through the surfactants across emulsion droplets and inhibits emulsion growth by unstable concentration variations of seed copolymers in emulsions. Therefore, Ostwald ripening was reduced by a higher feeding ratio of the cross-linker in the copolymer, which tends to produce smaller sized hollow nanoparticles.