Development of Self-Healable Organic/Inorganic Hybrid Materials Containing a Biobased Copolymer via Diels-Alder Chemistry and Their Application in Electromagnetic Interference Shielding

In this study, a novel biobased poly(ethylene brassylate)-poly(furfuryl glycidyl ether) copolymer (PEBF) copolymer was synthesized and applied as a structure-directing template to incorporate graphene and 1,1'-(methylenedi-4,1-phenylene)bismaleimide (BMI) to fabricate a series of self-healing organic/inorganic hybrid materials. This ternary material system provided different types of diene/dienophile pairs from the furan/maleimide, graphene/furan, and graphene/maleimide combinations to build a crosslinked network via multiple Diels-Alder (DA) reactions and synergistically co-assembled graphene sheets into the polymeric matrix with a uniform dispersibility. The PEBF/graphene/BMI hybrid system possessed an efficient self-repairability for healing structural defects and an electromagnetic interference shielding ability in the Ku-band frequency range. We believe that the development of the biobased self-healing hybrid system provides a promising direction for the creation of a new class of materials with the advantages of environmental friendliness as well as durability, and shows potential for use in advanced electromagnetic applications.

Study on Paramagnetic Interactions of (CH3NH3)2CoBr4 Hybrid Perovskites Based on Nuclear Magnetic Resonance (NMR) Relaxation Time

The thermal properties of organic-inorganic (CH3NH3)2CoBr4 crystals were investigated using differential scanning calorimetry and thermogravimetric analysis. The phase transition and partial decomposition temperatures were observed at 460 K and 572 K. Nuclear magnetic resonance (NMR) chemical shifts depend on the local field at the site of the resonating nucleus. In addition, temperature-dependent spin-lattice relaxation times (T1ρ) were measured using 1H and 13C magic angle spinning NMR to elucidate the paramagnetic interactions of the (CH3NH3)+ cations. The shortening of 1H and 13C T1ρ of the (CH3NH3)2CoBr4 crystals are due to the paramagnetic Co2+ effect. Moreover, the physical properties of (CH3NH3)2CoBr4 with paramagnetic ions and those of (CH3NH3)2CdBr4 without paramagnetic ions are reported and compared.

Anisotropic Growth of Hydroxyapatite in Stretched Double Network Hydrogel

Bone tissues possess excellent mechanical properties such as compatibility between strength and flexibility and load bearing owing to the hybridization of organic/inorganic matters with anisotropic structure. To synthetically mimic such an anisotropic structure of natural organic/inorganic hybrid materials, we carried out hydroxyapatite (HAp) mineralization in stretched tough double network (DN) hydrogels. Anisotropic mineralization of HAp took place in stretched hydrogels, as revealed by high brightness synchrotron X-ray scattering and transmission electron microscopic observation. The c-axis of mineralized HAp aligned along the stretching direction, and the orientation degree S calculated from scattering profiles increased with increasing in the elongation ratio λ of the DN gel, and S at λ = 4 became comparable to that of rabbit tibial bones. The morphology of HAp polycrystal gradually changed from spherical to unidirectional rod-like shape with increased elongation ratio. A possible mechanism for the anisotropic mineralization is proposed, which would be one of the keys to develop mechanically anisotropic organic/inorganic hybrid materials.