Hydroxyethyl cellulose. As cellulose, with ethoxy groups on carbon 6. HNBR. Hydrogenated nitrile butadiene rubber (hydrogenated acrylonitrileâbutadiene is ...
Chapter 13.0
Introduction to Clay–Polymer Nanocomposites (CPN) F. Bergayaa, C. Detellierb, J.-F. Lambertc and G. Lagalyd a
CRMD, CNRS-Universite´ d’Orle´ans, Orle´ans Cedex 2, France Department of Chemistry and Center for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario, Canada c LRS, UMR 7197 CNRS, UPMC University Paris 6, 4 Pl. Jussieu 75252, Paris Cedex 05, France d Institut fu¨r Anorganische Chemie, Christian-Albrechts-Universita¨t zu Kiel, Kiel, Germany b
The term ‘nanocomposite’, which is quite recent in the literature, was first used by Roy, Komarneni and their colleagues at the beginning of the 1980s in the context of sol–gel processes, on recognising the non-uniformity, at the nanometre level, of some materials obtained from sols and gels (Roy et al., 1984; Komarneni, 1992). To quote Roy et al. (1986), ‘Such materials are more appropriately described by the generic term “nanocomposites”. Nanocomposites are solids containing two (or more) nm size “regions” . . .which differ in composition and/or structure’. A subject search on the term ‘nanocomposite’ on the Web of Science resulted (March 2012) in the first and only reference published in 1986 (Roy et al., 1986). However, this term is now widely used. The increase has been nicely exponential since then, to reach a cumulative total of more than 54,500 hits at the end of 2011. It is now accepted to name a heterogeneous material a ‘nanocomposite’ when at least one of the component domains has a dimension ranging from some angstroms to several nanometres (Sanchez et al., 2005). What makes these materials interesting is that their properties can be significantly different from the properties of the individual components, resulting in some cases in dramatic synergistic properties. Term and concept are intimately mixed. A concept without a term that can properly and simply express it will not evolve. The use of this new term in the 1980s seeded the infatuation for these materials in the next two decades. Though the term is recent, and though the synthesis and study of these heterogeneous materials has been only recently purposively designed by humans, nature has, however, evolved in taking advantage of their properties. Examples of nanocomposites are numerous in nature: bones, teeth, shells, to name a few. Human-made nanocomposites can be found in archaeological studies. One of the best examples is the Maya Blue paint, prepared by the Developments in Clay Science, Vol. 5A. http://dx.doi.org/10.1016/B978-0-08-098258-8.00020-1 © 2013 Elsevier Ltd. All rights reserved.
655
656
Handbook of Clay Science
Mayas in the Yucatan peninsula by heating a local palygorskite sample with indigo obtained from the indigenous indigofera plant. The result is a material where indigo molecules are intimately associated with the tunnels of palygorskite, giving a highly resistant, robust blue paint. (Van Olphen, 1966; JoseYacaman et al., 1996; Hubbard et al., 2003; Domenech et al., 2009). Low amounts of inorganic nanoparticles added to polymers in which they are dispersed can enhance the performance of the polymers. What is probably the most spectacular and fruitful advance of the concept so far is the design of clay-based polymer nanocomposites (CPN) (Bergaya and Lagaly, 2007; Annabi-Bergaya, 2008). Small amounts (typically less than 5%) of a clay mineral dispersed in a polymer can dramatically improve some of the polymer properties. Essentially two main types of CPN can be considered: intercalated or exfoliated (Alexandre and Dubois, 2000). The three representations of (micro or nano) composites depicted in Fig. 13.0.1 are idealised cases, and intermediate situations are common. i. Microcomposites are dispersions of fine, micro-sized clay mineral particles in the polymer matrix. This was, until recently, the traditional way of reinforcing polymers.
(i) Clay–polymer microcomposite
(ii) Intercalated CPN
(iii) Exfoliated CPN FIGURE 13.0.1 The three idealised representations of (micro or nano) composites.
Chapter
13.0
Introduction to Clay–Polymer Nanocomposites
657
ii. Intercalated nanocomposites consist of the intercalation of polymer chains in a well-ordered fashion in the interlayer space of a layered clay mineral. In this case, the stacking of the layers is maintained, with ordering along the c-axis. Since the general term ‘delamination’ is used to designate the separation between the planar faces of two adjacent layers (Bergaya et al., 2011; see also Chapter 1), intercalated nanocomposites could also be called ‘delaminated nanocomposites’. iii. Exfoliated nanocomposites are formed by the complete separation of the individual layers of the clay mineral, resulting in a disordered dispersion of the individual clay mineral layers in the polymer matrix. The layers become completely independent from one another, and there is a loss of crystallographic orientation (Bergaya et al., 2011). Gardolinski and Lagaly (2005) made a distinction between these two terms when they applied them to clay minerals: ‘Delamination and exfoliation are terms used in modern literature, unfortunately often neglecting to distinguish between them. When dealing with clay minerals (and many other layered materials), a clear distinction between the two terms is easily established. Exfoliation was defined as the decomposition of large aggregates (booklets) into smaller particles. Delamination denoted the process of separation of the individual layers of the particles’. This definition has now been revised (Bergaya et al., 2011) and is given in Chapter 1. Obviously, exfoliated nanocomposites represent the limiting case of delamination when the separation of the individual layers results in their random dispersion in the polymer. One of the major characteristics of a clay mineral in order to optimise the performance of nanocomposites is to obtain the highest aspect ratio of the dispersed nanoparticles, or, in other words, the lowest number of layers per particle (Annabi-Bergaya, 2008). The limiting situation is one layer per particle (situation 3 of Fig. 13.0.1). Consequently, the development of CPN was based mainly on the 2:1 phyllosilicates constituting the smectite group, because they are easily swellable, and a large number and variety of hosts can be intercalated. The exfoliated clay minerals with 1–10% low-volume particles randomly dispersed in the polymeric matrix must, indeed, play an active role in the properties of the nanocomposites and in the enhancement of its desired characteristics. In particular, the interfacial interaction between the clay mineral layer and the organic polymer must have an impact on the strength and rheological properties of the CPN. Consequently, the nature and the structure of the clay mineral should influence the CPN’s properties. Thus, there is a need to develop the delamination and exfoliation chemistry of layered minerals other than those of the smectite group. Much of the research on CPN was carried out by polymer specialists, and many applications concern systems in which the clay mineral component represents a small, but important, fraction. Therefore, following the CPN literature implies some familiarity with polymer names; the most important ones
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature Abbreviation
Full name
Aramide
Aromatic polyamide
BCP
Block copolymer
BIMS
Poly(isobutylene-co-paramethylstryrene)
Structure
n
H3C CH3
CH3 BR
Polybutadiene rubber
n may exhibit cis double bonds and/or branching
CMC
Carboxymethyl cellulose
COO-
O OH O
HO
O
O
HO
O OH O COO-
Cellulose
OH OH O
HO
O
O
HO
n
O OH OH
Chitosan
OH
O O HO NH2
n
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
CNBR
Carboxylated acrylonitrile– butadiene rubber
CPVC
Chlorinated PVC
E-SBR
Emulsion stryrene butadiene rubber, see SBR
EMA
Poly (ethylmethacrylate)
Structure
n CH3 O
ENR
Epoxidised natural rubber
EPDM
Ethylene propylene diene monomer rubber
CH3
n CH3
CH3
EPM
Ethylene propylene monomer rubber
CH3
m Epon-828
n O
O
n
EPR
Ethylene–propylene rubber
EVA
Poly (ethylene-co-vinyl acetate)
Includes EPM and EPDM
CH3
O
m
O
n
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
EVOH
Ethylene–vinyl alcohol copolymer
Structure OH
m HDPE
High-density polyethylene
HEC
Hydroxyethyl cellulose
HNBR
Hydrogenated nitrile butadiene rubber (hydrogenated acrylonitrile–butadiene is shown)
n
As cellulose, with ethoxy groups on carbon 6
CN
n HPMC
Hydroxypropylmethyl cellulose
IR
Polyisoprene rubber
As cellulose, with (2-hydroxypropoxy) and methoxy groups on carbon 6
n H3C
IIR
Isoprene isobutylene rubber (isoprene isobutylene copolymer)
CH3
n H3C LDPE
Low-density polyethylene
LLDPE
Linear low-density polyethylene (shown is poly (ethylene-co-4methyl-1-pentene), trade name Innovex)
N6
Nylon 6, see PA-6
NBR
Nitrile butadiene rubber (acrylonitrile–butadiene is shown)
CH3
n
n
m C N
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
NR
Natural rubber
Nylon
Trade name for a family of polyamides. Nylon 6-6 is represented; see also PA-6
Structure
O H N N H
n
O P3HB or PHB
Poly(3-hydroxy butyrate)
O n O
CH3 P3HT
Poly(3-hexylthiophene)
S n
CH3
PA-6
A polyamide, also called Nylon-6
H N n O
PAA or PA
Polyacrylic acid or polyacrylate
n n
or O
O O
O
R PAAm
Poly(acrylamide)
n O
NH2
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
PAN
Poly(acrylonitrile)
Structure
n C
N PANI or
Polyaniline
H N
H N
N
N
n
m PBS, PBSA
Poly(butylene succinate)
O O n
O O
PBT
Poly(butylene terephthalate)
O O O
n
O PC
Polycarbonate
PCL
Poly (e-caprolactame)
See, e.g. SPC
O
O
PE
n
Polyethylene
n PECH
Poly(epichlorohydrin)
O n
Cl
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
PEDOT
Poly(3,4-ethylenedioxythiophene) (see PTh for comparison)
Structure S n
O
(s)PEEK
O
(sulfonated) poly(ether ether ketone)
O
O
HO3S
n O
PEG
Poly(ethylene glycol)
PEMA
Poly(ethylene/maleic anhydride)
Low molecular weight PEO
n
m
O PEI
Poly(ethylene imine)
N H PEO
n
Poly(ethylene oxide)
O
PET, PETA
O
O
Poly(ethylene terephthalate)
O
n
O
O
PETg
Glycosylated poly(ethylene terephthalate)
PHA
Poly(hydroxy alkanoate)
O
n
O n O
CH3
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
PIB
Poly(isobutene)¼poly(isobutylene)
Structure
n H3C CH3 P(L)LA
Poly (L-lactic acid)
O
O
n
CH3 PLG(A)
Poly(lactic–co-glycolic acid)
O O O
m
n O
CH3 PMAA
Poly(methacrylamide)
CH3 n C O
NH2
PMMA
Poly(methyl methacrylate)
CH3 n O
O CH3
PMP
Poly(4-methyl-1-pentene)
n CH3
CH3 PNIPAM
Poly(N-isopropyl acrylamide)
n O
NH CH H 3C
POE
Ethylene–octene copolymer
POSS
Polyhedral oligomeric silsesquioxanes
CH3
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
PP
Polypropylene
Structure
n CH3 PPO
Poly(phenylene oxide), more precisely poly(2,6-dimethyl-1,4phenylene oxide)
CH3
O
n
CH3 PPV
Poly(p-phenylene vinylene)
CH3
n
CH3
PPy
Polypyrrole
H N n
PS
Polystyrene
n
PT or PTh
Polythiophene
S n
PU
Polyurethane
e.g.
O H N
e.g.
O O
N H
n
O PVA
Poly(vinyl alcohol)
n OH
Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
PVC
Poly(vinyl chloride)
Structure
n Cl PVDF
Poly(vinylidene fluoride)
F2 C n
PVK
Poly(N-vinylcarbazole)
n N
PVP
Poly(vinyl pyrrolidone)
N O
n
SAN
Styrene–acrylonitrile
n
m C N
SBR
Styrene–butadiene rubber
m
SEBS
Styrene–ethylene–butylene– styrene block copolymer
SPC
Poly(bisphenol A carbonate)— Trade names Lexan, Makrolon, Makroclear
H3C
n
CH3
O
O
O
n Continued
TABLE 13.0.1 The Names, the Schemes and the Abbreviations of the Most Important Polymers Used in the CPN Literature— Cont’d Abbreviation
Full name
Structure
TPE
Thermoplastic elastomers
Includes TPO and TPU
TPO
Thermoplastic olefins
TPS
Thermoplastic starch
TPU
Thermoplastic polyurethane
XNBR
Carboxylated nitrile butadiene rubber
See PU
Chapter
13.0
Introduction to Clay–Polymer Nanocomposites
677
encountered in the field are listed in Table 13.0.1. The reader should refer to this table for the meaning of abbreviations used in the three following chapters and in Chapter 4.4 in Volume B. Chapter 13.1 is devoted to smectite–polymer nanocomposites, with an occasional mention of other TOT clay minerals. The more recently developed polymer nanocomposites based on non-swelling clay minerals are described in Chapter 13.2 (kaolinite–polymer nanocomposites) and Chapter 13.3 (sepiolite– and palygorskite–polymer nanocomposites). The numerous applications of CPN are fully described in Chapter 4.4 in Volume B.
REFERENCES Alexandre, M., Dubois, P., 2000. Polymer-layered silicate nanocomposites: preparation, properties and uses of a new class of materials. Mater. Sci. Eng. 28, 1–63. Annabi-Bergaya, F., 2008. Layered clay minerals. Basic research and innovative composite applications. Micr. Mes. Mater. 107, 141–148. Bergaya, F., Lagaly, G., 2007. Clay minerals properties responsible for clay-based polymer nanocomposites (cpn) performance. In: Carrado, K., Bergaya, F. (Eds.), Clay-based Polymer Nanocomposites (CPN). CMS Workshop Lecture, vol. 15. The Clay Minerals Society, Chantilly, pp. 61–97. Bergaya, F., Jaber, M., Lambert, J.F., 2011. Clays and Clay Minerals. In: Galimberti, M. (Ed.), Rubber-Clay Nanocomposites. Science, Technology, and Applications. Wiley Publications, New York, Chapter 1, 3–44. Domenech, A., Domenech-Carbo, M.T., Sanchez del Rio, M., Vazquez de Agredos Pascual, M.L., Lima, E., 2009. Maya Blue as nanostructured polyfunctional hybrid organic-inorganic material: the need to change paradigms. N. J. Chem. 33, 2371–2379. Gardolinski, J.E.F.C., Lagaly, G., 2005. Grafted organic derivatives of kaolinite: II. Intercalation of primary n-alkylamines and delamination. Clay Miner. 40, 547–556. Hubbard, B., Kuang, W., Moser, A., Facey, G.A., Detellier, C., 2003. Structural study of Maya blue: textural, thermal and solid-state multinuclear magnetic resonance characterization of the palygorskite-indigo and sepiolite-indigo adducts. Clays Clay Miner. 51, 318–326. Jose-Yacaman, M., Rendon, L., Arenas, J., Puche, M., Carmen, S., 1996. Maya blue paint: an ancient nanostructured material. Science 273, 223–225. Komarneni, S., 1992. Nanocomposites. J. Mater. Chem. 2, 1219–1230. Roy, R., Komarneni, S., Roy, D.M., 1984. Multi-phasic ceramic composites made by sol-gel technique. Mater. Res. Soc. Symp. Proc. 32, 347–359. Roy, R., Roy, R.A., Roy, D.M., 1986. Alternative perspectives on “quasi-crystallinity”: nonuniformity and nanocomposites. Mater. Lett. 4, 323–328. Sanchez, C., Julia´n, B., Belleville, P., Popall, M., 2005. Applications of hybrid organic-inorganic nanocomposites. J. Mater. Chem. 15, 3559–3592. Van Olphen, H., 1966. Maya blue: a clay-organic pigment? Science 154, 645–646.
