Abstract
N-Octyltrimethoxysilane (CAS No. 3069-40-7), silane coupling agent KH-831, is a monomeric medium-chain alkylfunctional silane. KH-831 is a clear colorless liquid and soluble in common non-polar organic solvents (e. G. Petroleum ether, toluene). However its low volatility and viscosity make KH-831 an easy-to-handle additive. During the hydrolysis reaction between water and KH-831 a certain amount of ethanol (VOC) is released.

Identification
Name    n-Octyltrimethoxysilane
Synonyms    Trimethoxyoctylsilane
Molecular Formula    C11H26O3Si
Molecular Weight    234.41
CAS Registry Number    3069-40-7
EINECS    221-338-7

Equivalents
Dow Corning Z-6672  
EVONIK Degussa Dynasylan OCTMO  
UCT Specialties (formerly Petrarch) O9840

Properties
Density    0.91
Boiling point    246 C degree
Viscosity    2 mPa. S
Flash point    102 C degree
Water solubility    REACTS

Application
N-Octyltrimethoxysilane (CAS No. 3069-40-7), silane coupling agent KH-831, is an important additive for many applications. Examples are:
KH-831 silane can be used as a surface modifier to generate hydrophobicity (e. G. On concrete, glass, inorganic pigments, or mineral fillers). The medium-chain alkyl functionality results in unique compound properties when KH-831 treated minerals or pigments are incorporated into polymers, e. G. Polyethylene or polypropylene. Loading levels of 0.5 to 1.5% wt. KH-831 based on the weight of fillers or pigments are typically recommended.
KH-831 silane can also be used to improve the compatibility of mineral fillers or pigments in polyolefins or to ease their dispersion in nonpolar matrices.
KH-831 silane is a small molecule to allow for deep penetration into the cementitious surface. This material reacts with moisture in the air and in the substrate in the presence of an alkaline or acidic environment to produce hydroxy groups. These hydroxy groups will bond with the substrate and itself to produce a hydrophobic treatment that inhibits water absorption into the substrate. An alkaline environment, such as new concrete, will catalyze the reaction and speed the formation of the hydrophobic surface.