Triethoxy(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silane

Surface tension

Link to relevant study record(s)

Reference

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2015-07-08

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted in accordance with a relevant test method and in compliance with a known quality system (ISO 17025)

Qualifier:

according to guideline

Guideline:

OECD Guideline 115 (Surface Tension of Aqueous Solutions)

Version / remarks:

adopted on 27 July 1995

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

Version / remarks:

Council Regulation (EC) No. 440-2008 of 30 May 2008

GLP compliance:

no

Other quality assurance:

ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)

Type of method:

ring method

Key result

Surface tension:

72.2 mN/m

Temp.:

20 °C

Conc.:

10 mg/L

Table 1: Result

	First run	Second run
Number of measurements	10	31
Total time [min:s]	8:24	19:47
Measurement time for last 10 runs [min:s]	8:24	4:58
Measurement 1	72.40	51.15
Measurement 2	72.39	57.21
Measurement 3	72.39	61.09
Measurement 4	72.39	63.61
Measurement 5	72.39	65.40
Measurement 6	72.38	66.67
Measurement 7	72.38	67.61
Measurement 8	72.38	68.34
Measurement 9	72.37	69.02
Measurement 10	72.38	69.59
Measurement 11	-	70.07
Measurement 12	-	70.45
Measurement 13	-	70.74
Measurement 14	-	71.01
Measurement 15	-	71.21
Measurement 16	-	71.38
Measurement 17	-	71.52
Measurement 18	-	71.62
Measurement 19	-	71.71
Measurement 20	-	71.79
Measurement 21	-	71.85
Measurement 22	-	71.91
Measurement 23	-	71.96
Measurement 24	-	72.00
Measurement 25	-	72.04
Measurement 26	-	72.09
Measurement 27	-	72.12
Measurement 28	-	72.14
Measurement 29	-	72.16
Measurement 30	-	72.19
Measurement 31	-	72.20
Surface tension [mN/m]^1	72.39	72.08
Mean value [mN/m]	72.2

1) Mean value of the last ten measurements

Conclusions:

A surface tension value of 72.2 mN/m at 20°C was obtained for 10 mg/l of the test substance using a relevant test method. The result is considered to be reliable.

Description of key information

Surface tension [2-(perfluorohexyl)ethyl]triethoxysilane: 72.2 mN/m at 20°C (OECD 115)

Surface tension [2-(perfluorohexyl)ethyl]silanetriol: <22 mN/m at 20°C (OECD 115)

Key value for chemical safety assessment

Surface tension:

72.2

in mN/m at 20°C and concentration in mg/L:

10

Additional information

A measured surface tension value of 72.2 mN/m at 20°C and 10 mg/l was determined for the substance using a relevant test method and in compliance with a known quality system (ISO 17025). The measurements were taken after a solution age of 30 minutes to minimise hydrolysis of the substance. The result is considered to be reliable and is selected as key study. Under the condition of the study, the parent substance, [2-(perfluorohexyl)ethyl]triethoxysilane is considered as not surface active.

 

In contact with water, [2-(perfluorohexyl)ethyl]triethoxysilane hydrolyse moderately rapidly to form [2-(perfluorohexyl)ethyl]silanetriol and ethanol. Therefore, the surface tension of the silanol hydrolysis product can be read-across from [2-(perfluorohexyl)ethyl]trimethoxysilane following the discussion below.

 

A surface tension study was conducted using a trimethoxy structural analogue, [2-(perfluorohexyl)ethyl]trimethoxysilane (CAS 85857-16-5), of the registration subtance. Under dilute conditions in water, [2-(perfluorohexyl)ethyl]trimethoxysilane hydrolyses faster when compared with the registration substance (hydrolysis half-life of 12.5 at pH 7 and 20°C), with a hydrolysis half-life of 8.8 h at pH 7 and 20-25°C. The surface tension study was conducted at 20°C using a 1 g/l solution aged for 43 h. Given the hydrolysis half-life of the trimethoxy structural analogue, the surface tension result is considered to reflect that of the silanol hydrolysis product(s), [2-(perfluorohexyl)ethyl]silanetriol and ethanol. Therefore, under these conditions, the silanol hydrolysis product has a measured surface tension of <22 mN/m at 20°C and 1 g/l.

 

Based on this available information and uses of the substance; the silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol, is considered to be surface active.

 

The corresponding monomeric silanetriol is expected to be surface active based on measured and read across data. The presence of fluorocarbon chains may mean that condensation products could have some surface activity. For these reasons, the effective limits of solubility of both the parent substance and monomeric silanol hydrolysis products are very low and all forms of the substance may have a tendency to enrich at surfaces rather than forming stable evenly dispersed solutions.