Phase-Separated Conetwork Structure Induced by Radical Copolymerization of Poly(dimethylsiloxane)-α,ω-diacrylate and N,N-Dimethylacrylamide

Organic-inorganic covalent-ionic molecules for elastic ceramic plastic

Although organic-inorganic hybrid materials have played indispensable roles as mechanical^1-4, optical^5,6, electronic^7,8 and biomedical materials^9-11, isolated organic-inorganic hybrid molecules (at present limited to covalent compounds^12,13) are seldom used to prepare hybrid materials, owing to the distinct behaviours of organic covalent bonds¹⁴ and inorganic ionic bonds¹⁵ in molecular construction. Here we integrate typical covalent and ionic bonds within one molecule to create an organic-inorganic hybrid molecule, which can be used for bottom-up syntheses of hybrid materials. A combination of the organic covalent thioctic acid (TA) and the inorganic ionic calcium carbonate oligomer (CCO) through an acid-base reaction provides a TA-CCO hybrid molecule with the representative molecular formula TA₂Ca(CaCO₃)₂. Its dual reactivity involving copolymerization of the organic TA segment and inorganic CCO segment generates the respective covalent and ionic networks. The two networks are interconnected through TA-CCO complexes to form a covalent-ionic bicontinuous structure within the resulting hybrid material, poly(TA-CCO), which unifies paradoxical mechanical properties. The reversible binding of Ca²⁺-CO₃^2- bonds in the ionic network and S-S bonds in the covalent network ensures material reprocessability with plastic-like mouldability while preserving thermal stability. The coexistence of ceramic-like, rubber-like and plastic-like behaviours within poly(TA-CCO) goes beyond current classifications of materials to generate an 'elastic ceramic plastic'. The bottom-up creation of organic-inorganic hybrid molecules provides a feasible pathway for the molecular engineering of hybrid materials, thereby supplementing the classical methodology used for the manufacture of organic-inorganic hybrid materials.

Designing Nanostructured 3D Printed Materials by Controlling Macromolecular Architecture

Nanostructured polymeric materials play important roles in many advanced applications, however, controlling the morphologies of polymeric thermosets remains a challenge. This work uses multi-arm macroCTAs to mediate polymerization-induced microphase separation (PIMS) and prepare nanostructured materials via photoinduced 3D printing. The characteristic length scale of microphase-separated domains is determined by the macroCTA arm length, while nanoscale morphologies are controlled by the macroCTA architecture. Specifically, using 2- and 4- arm macroCTAs provides materials with different morphologies compared to analogous monofunctional linear macroCTAs at similar compositions. The mechanical properties of these nanostructured thermosets can also be tuned while maintaining the desired morphologies. Using multi-arm macroCTAs can thus broaden the scope of accessible nanostructures for extended applications, including the fabrication of actuators and potential drug delivery devices.

Facile and Safe Synthesis of Novel Self-Pored Amine-Functionalized Polystyrene with Nanoscale Bicontinuous Morphology

The chloromethyl-functionalized polystyrene is the most commonly used ammonium cation precursor for making anion exchange resins (AER) and membranes (AEM). However, the chloromethylation of polystyrene or styrene involves highly toxic and carcinogenic raw materials (e.g., chloromethyl ether) and the resultant ammonium cation structural motif is not stable enough in alkaline media. Herein, we present a novel self-pored amine-functionalized polystyrene, which may provide a safe, convenient, and green process to make polystyrene-based AER and AEM. It is realized by hydrolysis of the copolymer obtained via random copolymerization of N-vinylformamide (NVF) with styrene (St). The composition and structure of the NVF-St copolymer could be controlled by monomeric ratio, and the copolymers with high NVF content could form bicontinuous morphology at sub-100 nm levels. Such bicontinuous morphology allows the copolymers to be swollen in water and self-pored by freeze-drying, yielding a large specific surface area. Thus, the copolymer exhibits high adsorption capacity (226 mg/g for bisphenol A). Further, the amine-functionalized polystyrene has all-carbon backbone and hydrophilic/hydrophobic microphase separation morphology. It can be quaternized to produce ammonium cations and would be an excellent precursor for making AEM and AER with good alkaline stability and smooth ion transport channels. Therefore, the present strategy may open a new pathway to develop porous alkaline stable AER and AEM without using metal catalysts, organic pore-forming agents, and carcinogenic raw materials.