Mechanical Strong,Highly Adhesive,Recyclable and Transparent Supramolecular Silicone Coatings with Easy Water/Oil Sliding

Traditional silicone materials have poor mechanical properties,poor interfacial adhesion and lack the ability to be reprocessed or recycled.Herein,we developed a novel strategy of incorporating dynamic noncovalent bonds(2-amino-4-hydroxy-6-methylpyrimidine(UPy))into side chain of silicone backbones to construct supramolecular silicone poly(urea-urethane)(SSPu)coatings with excellent mechanical performance,strong interfacial adhesion and multiple time recycling capability.Impressively,the prepared SSPu is endowed with simultaneously enhanced stiffness(272.0±23.2 MPa)and toughness(8.0±2.0 MJ·m^(-3)).Besides,SSPu shows strong interfacial adhesion(up to 9.0±1.3 MPa)to diverse substrate(stainless steel,aluminum,copper,epoxy and glass)with long term stability.Moreover,SSPu exhibits excellent multirecyclability and reusability without significantly decrease of its performance.In addition to the abovementioned features,the enrichment of siloxane backbones in the surface layer endows SSPu with robust repellency to water/oil.Our strategy provides a powerful route to fabricate a new multifunctional silicone elastomer.It is highly anticipated that our strategy can effectively extend the service life of silicone coating which can be applied in a wide variety of areas including self-cleaning,antifouling.

Flame-retardant Wrapped Ramie Fibers towards Suppressing “Candlewick Effect” of Polypropylene/Ramie Fiber Composites

In this work, a flame-retardant polypropylene（PP）/ramie fiber（RF） composite was prepared. The ramie fibers were wrapped chemically by a phosphorus- and nitrogen-containing flame retardant（FR） produced via in situ condensation reaction so as to suppress their candlewick effect. Fourier transform infrared spectroscopy（FTIR）, X-ray photoelectron spectroscopy（XPS） and scanning electron microscopy（SEM） demonstrated that the ramie fibers wrapped chemically by FR（FR-RF） were obtained successfully. Thermogravimatric test showed that the PP/FR-RF composite had more residue and better thermal stability at high temperatures than the PP/RF composite. Cone calorimeter（CC） results indicated that the peak of heat release rate（PHRR） and total heat release（THR） correspondingly decreased by 23.4% and 12.5% compared with the values of neat PP/RF. The PP/FR-RF composite created a continuous and compact char layer after the combustion. Combining FTIR analysis of char residue after CC test with heat conduction coefficient results, it could be concluded that the charring of FR on RF greatly weakened the candlewick effect of RF, and more char residue in the RF domain facilitated the formation of more continuous and compact char layer in the whole combustion zone, consequently protected PP composites during combustion, resulting in the better flame retardancy of PP/FR-RF composite than that of PP/RF composite.