One‐Step In Situ Synthesis of Polyamide Microcapsules With Inorganic Payload and Their Transformation into Responsive Thermoplastic Composite Materials

Abstract

Well‐dispersed loads of powdered metals, metal oxides, several carbon allotropes, or nanoclays are incorporated into polyamide 6 microcapsules (PAMC) via a one‐step in situ fabrication technique. It is based on activated anionic polymerization (AAP) of ϵ‐caprolactam in a hydrocarbon solvent performed in the presence of the respective micro‐ or nanosized loads. The forming PAMC are with controllable shape, size and load content. The results obtained show that the melt processing of PAMC is a facile method to fabricate thermoplastic hybrids with high mechanical resistance and tailored electro‐magnetic characteristics. This novel concept requires low polymerization temperatures, no functionalization or compatibilization of the loads and is scalable for industrial production levels.

Binary polyamide hybrid composites containing carbon allotropes and metal particles with radiofrequency shielding effect

“…Then, the initiator and the activator amounts were added whereby the polymerization of ECL to PA6 around each filler particle started at once. The chemistry of the process is described in detail in previous works . According to these studies it can be hypothesized that the mixed metal/carbon are entrapped into viscous oligomer droplets formed by growing PA6 polymer molecules.…”

“…The loaded PAMC were produced by solution‐precipitation AAROP of ECL performed as described in detail previously . In a typical polymerization process about 0.5 mol of ECL and the desired amount of carbon allotrope and metal powder (altogether up to 10 wt% in respect to ECL) were added to 100 mL of 1:1 toluene/xylene mixture while stirring, under nitrogen atmosphere, refluxing the reaction mixture for 10–15 min.…”

“…An attempt to overcome the above limitations and to extend the microencapsulation strategies toward the preparation of high‐strength composites based on n ‐polyamides was the use of activated anionic ring opening polymerization (AAROP) of lactams. Thus, reactive microencapsulation of various organic and inorganic loads by AAROP of ε‐caprolactam (ECL) in suspension to produce loaded polyamide 6 (PA6)‐based microcapsules (PAMCs) with their subsequent compression molding to PA6 hybrids was recently communicated . This fabrication concept allowed the synthesis of a number of particulate and laminated PA6 composites comprising various single organic or inorganic fillers in wide concentration ranges and with controlled dispersion .…”

Preparation and properties of metal-containing polyamide hybrid composites via reactive microencapsulation

“…On the other hand, polymer hybrids containing micron-sized metals are difficult to obtain by conventional melt processing of thermoplastics due to heavy aggregation issues. As communicated by us recently, the said problems can be solved in PA6 hybrid composites by means of a new microencapsulation strategy employing activated anionic polymerization (AAP) of ECL in suspension [25]. The process is carried out in a way to produce microcapsules whose PA6 porous shells entrap the micron-or nanosized filler particles.…”

Reactive microencapsulation of carbon allotropes in polyamide shell-core structures and their transformation in hybrid composites with tailored electrical properties

“…The process can be carried out in a way to produce micro-or nanosized capsules whose polyamide core entraps well-dispersed filler particles. The loaded capsules are further subjected to melt-processing to shape the final composite [36,37]. This novel method is characterized by short polymerization times of ca.…”