Block-assembling: a new strategy for fabricating conductive nanoporous materials from nanocomposites based on a melt-miscible crystalline/crystalline blend and MWCNTs

Abstract

As featured in:www.rsc.org/MaterialsC Showcasing research from the group of Prof. Yongjin Li, College of Materials, Chemistry and Chemical Engineering, Hangzhou Normal University.Block-assembling: a new strategy for fabricating conductive nanoporous materials from nanocomposites based on a melt-miscible crystalline/crystalline blend and MWCNTsConductive nanoporous materials were obtained from a "block-assembling" structure in ternary nanocomposites comprised of a melt-miscible crystalline/crystalline blend and MWCNTs, by selective removal of the component with poor capability of crystallization. See Yongjin Li et al., J. Mater. Chem. C, 2015, 3, 8510. 8510 | J. Mater. Chem. C, 2015, 3, 8510--8518 This journal is In this work, we focus on exploring a new method to prepare conductive nanoporous polymeric materials, by simply incorporating multi-walled carbon nanotubes (MWCNTs) into melt-miscible poly(L-lactic acid)/ poly(oxymethylene) (PLLA/POM) blends. The POM components in the ternary nanocomposites crystallize first to form ''nano-hybrid shish-kebab (NHSK)'' structures at a high temperature in the presence of MWCNTs, with the simultaneous exclusion of poorly crystallizable PLLA chains into the intra-NHSK regimes.The subsequent PLLA crystallization in the intra-NHSK regimes is also nucleated on the surface of MWCNTs and transforms the final crystal morphology into ''ternary-hybrid shish-kebab (THSK)'' superstructures.Therefore, a ''binary-polymer-decoration'' of MWCNTs, named ''block-assembling'', is achieved. Such a novel ''block-assembling'' structure is further used to fabricate conductive nanoporous polymeric materials with a unique interposition structure of CNTs in the inner wall of the internal pores after the removal of the PLLA components in the ternary nanocomposites.

Polyoxymethylene/Carbon Nanotube Self-Assembly Networks with Improved Electrical Conductivity for Engineering Functional Structural Materials

“…Polyoxymethylene (POM), as an engineering plastic with high strength and rigidity, excellent self-lubricating properties, and corrosion resistance, can be used as a substitute for metals widely used in automobiles, electronics, and machinery, and so forth. − However, POM is an electrically insulating material with electrical conductivity between 10 –15 and 10 –13 S/cm, which easily builds up static charge, leading to dust contamination, short circuit, and even fires or explosions in application. The antistatic property and conductivity of POM are usually improved by addition of antistatic agents, conductive fillers like carbon nanotubes (CNTs), carbon black (CB), and so forth. − CNTs are hollow tubes formed by coiling of graphene sheets around the central axis, which have excellent conductivity, and both ends of the unsealed end contain a certain number of hydroxyl and carboxyl groups with high reaction activity. − Research on the conductivity of POM/CNT nanocomposites has been reported. Hebin Yin et al prepared conductive POM composites by connecting high-aspect ratio multiwalled carbon nanotubes (MWCNTs) and conductive carbon black (CB) aggregates to construct a conductive pathway, which showed that when the content of the conductive filler was constant, the percolation threshold value of such POM composite was between the threshold of the two separate composites (0.9 wt % ∼ 6.73 wt %).…”

Adjusting Distribution of Multiwall Carbon Nanotubes in Poly(L-lactide)/Poly(oxymethylene) Blends via Constructing Stereocomplex Crystallites: Toward Conductive and Microwave Shielding Enhancement

“…64,65 However, there was similar distribution of MWCNTs in PLLA, POM, and PLLA/POM blends. 66,67 Fortunately, the effects of single-walled carbon nanotube (SWCNT) concentration and PLLA crystallinity on conductivity of PLLA/SWCNT composites have been reported. 68 Furthermore, the crystallinity of PLLA could be tuned in a wide range (0−50%), which could greatly help to reconstruct the MWCNT networks in the composites.…”

“…Although the compatible polymers could overcome this disadvantage, it was hard to control distribution of conductive fillers in compatible polymer blends. Poly­(oxymethylene) (POM), which is miscible with PLLA, was used to modify the properties of PLLA. , However, there was similar distribution of MWCNTs in PLLA, POM, and PLLA/POM blends. , Fortunately, the effects of single-walled carbon nanotube (SWCNT) concentration and PLLA crystallinity on conductivity of PLLA/SWCNT composites have been reported . Furthermore, the crystallinity of PLLA could be tuned in a wide range (0–50%), which could greatly help to reconstruct the MWCNT networks in the composites. − …”

Development and optimization of selective laser sintered-composites and structures for functional applications

“…Surface modification has been revealed to be effective strategies to realize the multi-functionality of carbon nanomaterials and optimize their composite performance [40,169]. The covalent and non-covalent functionalization of CNTs can be implemented to change their surface hydrophobicity and improve their dispersity in an aqueous solution.…”

“…The differences induced by cholate ion functionalized MWCNTs and their influences on the thermal behaviours of the composite powders were closely associated with the molecular structures and their interactions with MWCNTs. Molecular dynamic simulation [169] has revealed that cholate ion molecules, unlike conventional linear surfactants such as SDS, are rigid facial amphiphiles as shown in Fig. 3 This method has the great advantage that polymer powders could achieve a uniform layer of networking nanocarbon fillers via CNTs at the low weight percentage range of 0.1-1%.…”