Rational interface design of epoxy-organoclay nanocomposites: role of structure-property relationship for silane modifiers.
Montmorillonite was modified by three silane surfactants with different functionalities to investigate the role of surfactant structure on the properties of a final epoxy-organoclay nanocomposite. N-aminopropyldimethylethoxysilane (APDMES), an aminated monofunctional silane, was chosen as a promising surfactant for several reasons: (1) it will bond to silica in montmorillonite, (2) it will bond to epoxide groups, and (3) to overcome difficulties found with trifunctional aminosilane bonding clay layers together and preventing exfoliation. A trifunctional and non-aminated version of APDMES, 3-aminopropyltriethoxysilane (APTES) and n-propyldimethylmethoxysilane (PDMMS), respectively, was also studied to provide comparison to this rationally chosen surfactant. APDMES and APTES were grafted onto montmorillonite in the same amount, while PDMMS was barely grafted (<1 wt%). The gallery spacing of APDMES organoclay was greater than APTES or PDMMS, but the final nanocomposite gallery spacing was not dependent on the surfactant used. Different concentrations of APDMES modified montmorillonite yielded different properties, as concentration decreased glass transition temperature increased, thermal stability increased, and the storage modulus decreased. Storage modulus, glass transition temperature, and thermal stability were more similar for epoxy-organoclay composites modified with the same concentration of silane surfactant, neat epoxy, and epoxy-montmorillonite nanocomposite.
School of Materials Engineering, Purdue University, 701 W Stadium Ave., West Lafayette, IN 47907, USA. Electronic address: bruce7@purdue.edu.
Alex N
AN
Bruce
Division of Environmental and Ecological Engineering, Purdue University, 500 Central Dr., West Lafayette, IN 47907, USA. Electronic address: danielle.lieber@stonybrook.edu.
Danielle
D
Lieber
Division of Environmental and Ecological Engineering, Purdue University, 500 Central Dr., West Lafayette, IN 47907, USA; School of Civil Engineering, Purdue University, 550 Stadium Mall Dr., West Lafayette, IN 47907, USA. Electronic address: hua@purdue.edu.
Inez
I
Hua
School of Materials Engineering, Purdue University, 701 W Stadium Ave., West Lafayette, IN 47907, USA; Division of Environmental and Ecological Engineering, Purdue University, 500 Central Dr., West Lafayette, IN 47907, USA. Electronic address: howarter@purdue.edu.
John A
JA
Howarter
Epoxy–clay nanocomposite; Monofunctional silane surfactant; Montmorillonite modification; N-aminopropyldimethylethoxysilane; Silane ogranoclays