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Organically and silylation of synthesis nano- clay-Magadiite
Jung –Jie Huang1a Yaw-Nan Shieh1b＊Sea-Fue Wang2, Ming-Liang Lin2
1Department of Materials Science and Engineering Mingdao University*369Wen-Hwa Rd. Peetow,
Chang-Hua, Taiwan
2Department of Materials and Resources Engineering, National Taipei University of Technology,1,
Sec. 3 Chung-Hsiao E. Rd., Taipei, Taiwan
Keywords: Magadiite; Nano composites; Polymer-matrix composite (PMCs) ;Thermal properties;
X-ray Diffraction
Abstract
This paper is an investigation of the properties of covalently bonded magadiite/polyimide
nanocomposites synthesized with magadiite and polyimide（PI） . Synthesized magadiite was
organically modified by n-hexadecyl trimethyl-ammonium bromide (CTAB) and then grafted by
γ-aminopropyltriethoxysilane (APTS) γ-glycidoxypropyltrimethoxysilane( GPS ) or
γ-methacryloxy-propyltrimethoxysilane ( MPS ). XRD confirmed the formation of the
CTAB-magadiite and showed that the basal spacing increased from 1.54 to 2.46 nm.
Three silylating reagents, APTS ,GPS and MPS, were reacted with the CTAB- exchanged magadiite.
The subsequent formation of the organic derivatives was confirmed by XRD (X-ray diffractometer),
FTIR (Fourier transform infrared spectrometer), and 29
Si CP-MAS NMR (Solid-state nuclear
magnetic resonance ) spectra. The copolymerization of the APTS- GPS- and MPS- modified
magadiite produced new layered silicate-organic compounds and each one contained covalent bonds
between the interlayer spaces. This structure is dissimilar to that produced using conventional clay
polymer systems in which the ionic interactions between silicates and organic modifiers are
dominant.
Introduction
The construction of organic–inorganic nanocomposites has attracted considerable attention in the
field of materials chemistry. Composite materials are typically formed when at least two distinctly
dissimilar materials are mixed to form a monolith.
The overall properties of a composite material are determined not only by the properties of the parent
components but also by the morphology, volume fractions, and connectivity of the phases as well as
the interfacial properties [1,2]. Host-guest composites based on the intercalation of guest molecules
into inorganic layered hosts represent a new class of premier functional materials with new
functionalities such as catalyst properties and molecular sieving properties. These host-guest
composite thus possess unique chemical and physical characteristics [3–9].
The intercalation of the inorganic layered hosts can be used to facilitate the exfoliation of the
inorganic nanolayers into a polymer network, which maximizes the interfacial contact between the
organic and inorganic phases.
The exfoliated nanocomposites show a better phase homogeneity than the intercalated
nanocomposites, and show effectively improved the performances compared with other clay
composite materials [2,10].
Layered silicate magadiite clay is a good candidate for the formation of organic–inorganic
nanocomposites. This is partly because the magadiite has chemically stable siloxane surfaces and a
high surface area [11,14].
It also possesses a high aspect ratio. Magadiite forms a series of sodium polysilicate with the formula
of Na2O-14SiO2-nH2O [8,11,12]. The model structure of magadiite is shown in Fig. 1.
Advanced Materials Research Vols. 468-471 (2012) pp 2445-2449Online available since 2012/Feb/27 at www.scientific.net© (2012) Trans Tech Publications, Switzerlanddoi:10.4028/www.scientific.net/AMR.468-471.2445
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP,www.ttp.net. (ID: 130.194.20.173, Monash University Library, Clayton, Australia-10/03/13,18:30:52)
Magadiite is composed of one or more negatively charged sheets of SiO4 tetrahedra with abundant
silanol-terminated surfaces.
The negative charges in the layers of magadiite are balanced by either Na+
or H+ in the interlayer
spaces [13].
Magadiite has a high capacity for ion exchange, whereby the sodium ions can be replaced by protons,
other cations or large quaternary ammonium ions [6,11,14–20].
The surfaces of magadiite contain silanol groups (x Si–OH) and siloxide groups (x Si–O). The
interface between these silicate layers contains Na+ and H2O. Organic groups can be grafted to these
silanol groups and siloxide groups by reaction with silane to modify the interlayer space.
The grafting of organic derivatives of inorganic layered materials has the capability of further
accommodating of organic molecules due to the organophilicity of the interlayer surfaces.
Altering the size and number of the modifying organic groups, result in the emergence of unique
properties for each construct, including the selective and specific introduction of guest species, have
emerged.
In this study, n-hexadecyl trimethyl-ammonium bromide (CTAB) was applied as an intercalation
agent to facilitate cation exchange and organically modify the magadiite.
The silane coupling agents of γ-Aminopropyltriethoxysilane (APTS),
γ-glycidoxypropyltrimethoxysilane( GPS ) and γ-methacryloxy-propyltrimethoxysilane ( MPS ),
were used as silylating reagents to react with the CTAB exchanged magadiite.
The organically modified magadiite was mixed with poly(amic acid) (PAA) in a process of
imidization to form APTS-magadiite/PI and GPS-magadiite/PI nanocomposites.
The APTS-magadiite/PI and GPS-magadiite/PI nanocomposites were characterized using X-ray
diffraction (XRD), infrared spectroscopy(FTIR) and 29
Si CP-MAS solid-state nuclear magnetic
resonance (NMR) spectroscopy.
Analysis revealed that the APTS-magadiite/PI and GPS-magadiite/PI nanocomposite have lower
water absorption than that of pure polyimide (PI) this is a very important property for industrial
application such as flexible PCB board.
2. Experimental procedure
2.1. Materials
Hydrothermally synthesized clay (Na-magadiite) with a cation exchange capacity (CEC) equal to 100
meq/100 g (Chang-chun Petrochemical Co.,Taiwan), N-dimethylacetamide (DMAC, 98%; Tedia
Co.), CTAB, APTS, GPS and MPS were used in this study.
2.2. Intercalation layer of silica (CTAB-magadiite ) Na-magadiite was added to DMAC
(N,N-Dimethylacetamide) solvent and mixed for several hours. Additionally, CTAB was mixed with
DMAC solvent for several hours in a separate reaction. The above two solutions were then
simultaneously poured into a reactor together and stirred for 72 h at a temperature of 80oC.
The subsequently, the reacted product was separated from solution by centrifugation, washed several
times with acetone, air dried and then ground using mortar.
2.3. Silylation of the CTAB-magadiite intermediate
Five grams of powdered CTAB-magadiite was baked for 2 hr at 100oC. The sample was then mixed
with DMAC and stirred for 2 hours in a nitrogen atmosphere at the temperature of 50oC. Following
this, APTS (15ml) was added and the solution was mixed for 72 h at 80oC, the mixture was then
washed several times with DMAC. The same reaction conditions were applied when GPS and MPS
were used as the grafting agent. Lastly, products were filtered and dried, and APTS-magadiite,
GPS-magadiite, and MPS-magadiite were obtained.
2446 Automation Equipment and Systems
1. Results and discussion
The XRD patterns of each of the five different forms of magadiite is shown in Figure2. The
XRD-diffraction peaks indicate that the d-spacings of Na-magadiite and CTAB-magadiite are 1.543
and 2.48 nm respectively.APTS-magadiite(diffraction peak at 2θ=3.52° d-spacing =2.40 nm), are
associated with the diffraction of the (001) phase.
These results reveal that the interlayers of the silicate are intercalated with the APTS,GPS and MPS.
The chemical structures of the covalently bonded APTS, GPS and MPS used to graft onto the CTAB-
magadiite are shown in Figure 3. The peaks at -100ppm to -102ppm and -110ppm to -114ppm (Q3 and
Q4), represent the chemical structures of Si(OSi)3OH and Si(OSi)4, respectively in the layered
silicates of magadiite (Figure3a).The spectrum of APTS-magadiite (Figure 3b), GPS-magadiite
(Figure 3c) and MPS-magadiite (Figure 3d) included not only Q3 (-100ppm to -102ppm) and Q
4
(-110ppm to -114ppm) peaks but also T2 (-55ppm to -61ppm ) and T
3 (-66ppm to - 70ppm ) peaks.
The Q3 peaks indicates the structure【Si(OSi)3OH】 while the Q
4 peak may be associated with the
【Si(OSi)4】, which indicates hydrophilic groups on the surface of magadiite. The peak at T2
represents the structure of 【Si(OSi)2(OR’)R】 and T3
represents 【Si(OSi)3OR】. Both of these are
organic functional groups that bonded onto the surface of the layered silicate after silylation, as shown
in Figure 3. These results demonstrate that the silane of APTS, GPS and MPS was successfully
grafted onto the layered silicate (magadiite), suggesting that the surface of magadiite was already
silylated and organized. partially exfoliated.
Summary
The XRD results proved that intercalating a large quaternary ammonium ion such as in
CTAB,APTS,MPS and GPS can increase the basal spacing of Na-magadiite.The Si29
solid-state
NMR spectra revealed the chemical structure of the covalently bonded of APTS, GPS and MPS which
were grafted onto the silicates layers of magadiite.. The thermal degradation temperature (Td) of the
nanocomposites declines as the amount of Magadiite increases.
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2 4 6 8 10 12 14
5.910(1.53nm)
(a)
AIR
2 Theta
3.660(2.46nm) 6.99°
(b)
3.520(2.50nm)
(c)
Inte
ns
ity
3.610(2.48nm)
(d)
3.620(2.47nm)
(e)
Figure 2. X-ray diffraction (XRD) patterns of (a)
Na-magadiite, (b) CTAB-magadiite, (c) APTS-magadiite, (d)
GPS-magadiite, (e) MPS-magadiite.
2448 Automation Equipment and Systems
T2
T3 Q3
Q4
Chemical shift (δ/ppm)
Fig.3a. 29
Si Solid-state CP-MAS NMR spectra of APTS-magadiite (T2 represents the structure of【Si(OSi)2(OR’)R
】and T3 of 【Si(OSi)3OR】, peak Q3 indicating the structure【Si(OSi)3OH】 and peak Q4 of【Si(OSi)4】)
Fig.3b.
29Si Solid-state CP-MAS NMR spectra of GPS-magadiite(T
2 represents the structure of【Si(OSi)2(OR’)R】and
T3 of 【Si(OSi)3OR】, peak Q3 indicating the structure【Si(OSi)3OH】 and peak Q4 of【Si(OSi)4】)
Fig.3c.
29Si Solid-state CP-MAS NMR spectra of MPS-magadiite(T2 represents the structure of 【
Si(OSi)2(OR’)R】and T3 of 【Si(OSi)3OR】, peak Q3 indicating the structure 【Si(OSi)3OH】 and peak Q4
of【Si(OSi)4】)
Chemical shift (δ/ppm)
Advanced Materials Research Vols. 468-471 2449
Automation Equipment and Systems 10.4028/www.scientific.net/AMR.468-471 Organically and Silylation of Synthesis Nano- Clay-Magadiite 10.4028/www.scientific.net/AMR.468-471.2445
