Trimethoxyoctadecylsilane

Surface tension

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

surface tension

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reference 2

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Justification for type of information:

Refer to endpoint summary for further information.

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

GLP compliance:

no

Type of method:

plate method

Surface tension:

56.35 mN/m

Temp.:

20 °C

Remarks on result:

other: measured at saturation concentration

Results:

No.	Time after transferring to the measurement vessel (min)	Measured surface tension (mN/m)	Corrected surface tension (mN/m)
1	30	56.38	-
2	35	56.34	-
3	40	56.36	-
4	45	56.34	-
5	50	56.36	-
6	55	56.36	-
7	60	56.35	-
Total mean value:		56.35	-
Mean value (state of equilibrium)		56.35

When preparing the test solution (100 mg/l) with the buffer solution pH 7, the substance reacts at once with water with generation of a flocculent white precipitate. After 3 days the precipitate doesn’t disappear. Before measurement at 20 °C the precipitate is removed by filtration.

Conclusions:

The substance trichloro(hexadecyl)silane hydrolyses rapidly in water to form hexadecylsilanetriol. Therefore, the surface tension of the hydrolysis product, hexadecylsilanetriol (generated by the dissolution of trichloro(hexadecyl)silane in water) was measured to be 56.35 mN/m at 20 °C (at saturation concentration). The hydrolysis product is considered to be slightly surface active.

Reference 3

Endpoint:

surface tension

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the attached justification below and the overall justification for grouping of substances attached in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Surface tension:

56.35 mN/m

Temp.:

20 °C

Remarks on result:

other: measured at saturation concentration

Conclusions:

The substance trichloro(hexadecyl)silane hydrolyses rapidly in water to form hexadecylsilanetriol. Therefore, the surface tension of the hydrolysis product, hexadecylsilanetriol (generated by the dissolution of trichloro(hexadecyl)silane in water) was measured to be 56.35 mN/m at 20 °C (at saturation concentration). The hydrolysis product is considered to be slightly surface active.

Description of key information

Surface tension (trimethoxyoctadecylsilane); not relevant

Silanol hydrolysis product: approximately 56.35 mN/m at 20 °C (read-across from hexadecylsilanetriol)

Additional information

The requirement to test the substance for surface tension is waived because in contact with water the substance rapidly hydrolyses to form octadecylsilanetriol and methanol. There are no reliable measured data for the surface tension of octadecylsilanetriol.

It is appropriate to read-across surface tension data from structurally related fatty alkyl silanes, such as hexadecylsilanetriol. Hexadecylsilanetriol has a surface tension value of 56.35 °C in a reliable study using a relevant test method (reliability 1; read across conclusion is given reliability 2). As such, it is considered to be slightly surface active.

Details on the read across justification can be found in the attached justification in the respective target entry and in the overall justification for grouping of substances attached in IUCLID Section 13.