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

Surface tension

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

surface tension

Data waiving:

study technically not feasible

Justification for data waiving:

other:

Reference 2

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2014-10-09

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was conducted in accordance with an appropriate test method and in compliance with an appropriate quality system

Qualifier:

according to guideline

Guideline:

OECD Guideline 115 (Surface Tension of Aqueous Solutions)

GLP compliance:

no

Other quality assurance:

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

Type of method:

ring method

Surface tension:

< 22 mN/m

Temp.:

20 °C

Conc.:

1 g/L

Result

	First run	Second run
Number of measurements	1	2
Total measuring time [min:s]	1.59	1.52
Measuring time of the last 10 measurements [min:s]	Only one value was generated	Only two values were generated
Measurement 1	22.3	25.7
Measurement 2	-	21.7
Surface tension [mN/m]	22.3	21.7
Mean value [mN/m]	22.0

 

Surface tension (at 20°C): < 22,0 mN/m (at 1.0 g/l)

The test item is surface active.

Conclusions:

A surface tension value of<22 mN/m was obtained for the silanol hydrolysis product of the submission substance using a relevant test method.

Reference 3

Endpoint:

surface tension

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

2011-07-01 to 2011-07-04

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

The study was conducted in accordance with an appropriate test method but not in compliance with GLP.

Qualifier:

according to guideline

Guideline:

EU Method A.5 (Surface Tension)

Deviations:

no

GLP compliance:

no

Type of method:

plate method

Surface tension:

42.18 mN/m

Temp.:

20 °C

Conc.:

100 mg/L

Remarks on result:

other: Non-buffered result

Surface tension:

52.78 mN/m

Temp.:

20 °C

Conc.:

100 mg/L

Remarks on result:

other: Buffered result at pH 7

Test Conditions (de-ionized water):

When preparing the test solution (100 mg/l), the substance was observed to react rapidly with water with the generation of HCl and a flocculent white precipitate. After stirring for 4 hours and heating to 60°C the precipitate did not disappear. Before measurement at 20°C the precipitate was removed by filtration.

The concentration of the test substance was determined using the method for total carbon in the solution according to DIN EN 1484 H3. No carbon could be detected (detection limit < 3 mg/l). Additionally a 1H-NMR spectrum was measured. There was no signal of CH2Si or CH2 groups of an octyl chain. Therefore there is no indication of the test substance or organic groups as products of hydrolysis in the aqueous solution (detection limit < 10 mg/l).

Due to the very low concentration of dissolved material, it is difficult to interpret the result of the study.

The test substance was expected to hydrolyse rapidly generating HCl which will lower the pH of the solution. The condensation reaction of the silanol hydrolysis product are expected to be promoted at lower pH. Therefore the study was repeated in a pH 7 buffer solution as test medium.

Table 1: Surface tension result for non-neutralised (non-buffered solution)

No	Time after transferring to the measurement vessel [min]	Measured surface tension [mN/m]	Corrected surface tension [mN/m]
1	30	42.20	-
2	35	42.18	-
3	40	42.15	-
4	45	42.18	-
5	50	42.18	-
Total mean value		42.18	-
Mean value (state of equilibrium)		42.18	-

Test Conditions (pH 7 buffer solution):

When preparing the test solution (100 mg/l) with the buffer solution at pH 7, the substance was observed to react at rapidly with water with flocculent white precipitate being generated. After 3 days the precipitate did not disappear. Before measurement at 20°C the precipitate was removed by filtration.

A 1H-NMR spectrum of the test solution was measured. There was no signal of CH2Si or CH2 groups of an octyl chain. Therefore there is no indication of the test substance or organic groups as products of hydrolysis in the aqueous solution (detection limit < 10 mg/l).

It was assumed that a very small amount of the hydrolysis product of the test substance remained on the surface of the aqueous solution. This was considered a possible reason for the effect of surface tension.

Table 2: Surface tension result for neutralised (buffered solution)

No	Time after transferring to the measurement vessel [min]	Measured surface tension [mN/m]	Corrected surface tension [mN/m]
1	30	52.82	-
2	35	52.78	-
3	40	52.80	-
4	45	52.76	-
5	50	52.76	-
6	55	52.78	-
7	60	52.78	-
Total mean value		52.78	-
Mean value (state of equilibrium)		52.78	-

 

Conclusions:

A surface tension of octylsilanetriol, a hydrolysis product of octyltrichlorosilane, was determined as 53 mN/m using a relevant test method. The hydrolysis product (octylsilanetriol) was determined to be potentially surface active using a relevant test method. Significant condensation of the test substance was observed in water and there was no indication of the test substance or organic groups as product of hydrolysis in aqueous solution, thus the result is difficult to interpret. However, the surface activity observed was assumed to be as a result of a very small amount of the hydrolysis product which remained on the surface of the aqueous solution.

Description of key information

Surface tension [2-(perfluorohexyl)ethyl]trichlorosilane: Not relevant

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

Additional information

The requirement to conduct a surface tension study for the submission substance is waived in accordance with Section 2 of REACH Annex XI, because in contact with water, the substance reacts very rapidly to form [2-(perfluorohexyl)ethyl]silanetriol and hydrochloric acid. The surface tension of the silanol hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol was read-across from a study with the related substance, [2-(perfluorohexyl)ethyl]trimethoxysilane (CAS No. 85857-16-5). In addition, as supporting data, surface tension was also read-across from octyltrichlorosilane (CAS No. 5283-66-9).

Both [2-(perfluorohexyl)ethyl]trichlorosilane (CAS No. 78560-45-9) and [2-(perfluorohexyl)ethyl]trimethoxysilane (CAS No. 85857-16-5) have the same hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol.

The surface tension study used a test substance [[2-(perfluorohexyl)ethyl]trimethoxysilane, CAS No. 85857-16-5], under conditions in which the results would reflect the surface tension of the hydrolysis product. The surface tension study used a test concentration of 1 g/l at 20°C and 43 h solution age. At the age of the solution used during the study (43 h), hydrolysis would have occurred and the surface tension result is considered to reflect the silanol hydrolysis product(s) under conditions where the limit of solubility is significantly exceeded. Therefore, the study results are considered to indicate that the hydrolysis product, [2-(perfluorohexyl)ethyl]silanetriol has a measured surface tension value of <22 mN/m at 20°C and 1 g/l. This value is also supported by available measured data for the read-across substance octylsilanetriol.

The surface tension of octylsilanetriol was determined by the addition of octyltrichlorosilane to water. Octyltrichlorosilane (CAS No 5283-66-9) in contact with water reacts very rapidly with a half-life of <1 minute at pH 4, pH 7 and pH 9 and 25°C to form octylsilanetriol and hydrochloric acid. Both buffered (pH 7) and non-buffered solutions with solution age of 3 days and 4 hours respectively were used during the study. A surface tension of 53 mN/m at 20°C and 100 mg/l using EU Method A.5 was obtained for the buffered solution of octylsilanetriol. The result indicates that octylsilanetriol is slightly surface active.

The presence of fluorocarbon chains may mean that the 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.

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