Progress in Organic Coatings 80 (2015) 71–76 Contents lists available at ScienceDirect Progress in Organic Coatings j o ur na l ho me pa ge: www.elsevier.com/locate/porgcoat Development of carboxylated multi-walled carbon nanotubes reinforced potentially biodegradable poly(amide–imide) based on N-trimellitylimido-S-valine matrixes: Preparation, processing, and thermal properties Amir Abdolmaleki a,b,∗ , Shadpour Mallakpour a,b,c,∗∗ , Maryam Rostami a a Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111, Iran b Nanotechnology and Advanced Materials Institute, Isfahan University of Technology, Isfahan, 84156-83111, Iran c Center of Excellence in Sensors and Green Chemistry, Department of Chemistry, Isfahan University of Technology, Isfahan, 84156-83111, Iran a r t i c l e i n f o Article history: Received 27 September 2014 Accepted 21 November 2014 Keywords: Carbon nanotubes Nanocomposites Optically active polymer Poly)amide–imide) a b s t r a c t The present study reports the synthesis and characterization of some new nanocomposites (NC)s of carboxylated multi-walled carbon nanotubes (CA-MWCNTs) that reinforced a biodegradable poly(amide–imide) (PAI). First, a biodegradable PAI with flexible chiral unit in the backbone was syn- thesized via direct polycondensation, from an optically active synthesized N-trimellitylimido-S-valine diacid, and 4,4 ′ -methylenebis(3-chloro-2,6-diethylaniline) (MCDEA) in tetrabuthylammonium bromide as a green media. Then, PAI/CA-MWCNT NCs have been produced via a simple ultrasonically assisted solution mixing method. The prepared NCs were studied with Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis techniques. The results showed that a fine dispersion of CA-MWCNT bundles in the PAI matrix. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Different from the other allotropes of carbon, such as graphite, diamond, and fullerene (C60, C70, etc.), carbon nanotubes (CNT)s are one dimensional carbon materials which can have an aspect ratio greater than 1000 [1]. CNTs have many advantages in terms of electrical and thermal properties. These properties make CNTs an ideal material for using in areas such as thermal conductors, energy storage, conductive adhesive, field emission, thermal materials, structural materials, catalyst supports, biological applications, fibers, air and water filtration, ceramics, and other applications [2]. Also, it makes them a promising candidate in preparing high performance composites, especially in the field of polymer ∗ Corresponding author at: Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Tel.: +98 31 3391 3249; fax: +98 31 3391 2350. ∗∗ Corresponding author at: Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran. Tel.: +98 31 3391 3267; fax: +98 31 3391 2350. E-mail addresses: abdolmaleki@cc.iut.ac.ir, amirabdolmaleki@yahoo.com, abdolmaleki@gmail.com (A. Abdolmaleki), mallak777@yahoo.com, mallakpour84@alumni.ufl.edu, mallak@cc.iut.ac.ir (S. Mallakpour). composites [3]. Strong interfacial interaction between CNTs and polymer matrix is essential for fine dispersion of CNTs [4]. How- ever, this condition is difficult to achieve with raw CNTs, which have tendency to aggregate and create agglomerates held together due to van der Waals interactions [5]. Most of the techniques such as ultrasonication, addition of surfactant, and chemical modifica- tion of the nanotube surface have been used to solve the above mentioned problem [6]. Functionalization of CNTs is the most appli- cable and effective method to prevent aggregation of nanotubes [7–12]. Chiral phenomenon plays an important role in nature. Amino acids are among the simplest chiral biomolecules that include intramolecular hydrogen bonds and they supply as building blocks of more complex peptides and proteins [13]. Aromatic poly(amide–imide)s (PAI)s containing both amide and heterocy- cle imide with chiral structures are biologically very important. Moreover, the PAIs have excellent thermal, physical, mechani- cal properties, and easier processability [14–16]. In this study a biodegradable chiral PAI was utilized to prepare nanocom- posites (NC)s also carboxylated multi-walled carbon nanotubes (CA-MWCNT) was used to well disperse nanotubes into the polymer matrix. PAI/CA-MWCNT NCs were prepared with a sim- ple ultrasonically assisted solution and were characterized by http://dx.doi.org/10.1016/j.porgcoat.2014.11.019 0300-9440/© 2014 Elsevier B.V. All rights reserved.