Silane compound containing perfluoro(poly)ether group

A perfluoro(poly)ether group containing silane compound of the formula (1):

• (Rf-PFPE)α—X—(SiQkY3-k)β (1)
• wherein:
• Rf represents, each independently at each occurrence, a C1-16 alkyl which may be substituted by one or more fluorine atoms;
• PFPE represents —(OC4F8)a—(OC3F6)b—(OC2F4)c—(OCF2)d—
• wherein a, b, c and d are each independently an integer of 0 or more and 200 or less, the sum of a, b, c and d is 1 or more and the occurrence order of the respective repeating units in parentheses with the subscript a, b, c or d is not limited in the formula;
• X represents, each independently at each occurrence, a 3-10 valent organic group;
• Y represents, each independently at each occurrence, a hydrogen atom, a hydroxyl group, a hydrolyzable group, or a hydrocarbon group;
• with the proviso that a compound of the formula (I) wherein k=1 and all Y are an alkyl group in all units in parentheses with the subscript β is excepted;
• Q represents, each independently at each occurrence, —Z—SiR1pR23−p;
• Z represents, each independently at each occurrence, a divalent organic group:
• with the proviso that Z is not a group which forms a siloxane bond together with a Si atom present in the end of the formula (1),
• R1 represents, each independently at each occurrence, a hydroxyl group or a hydrolyzable group;
• R2 represents, each independently at each occurrence, a C1-22 alkyl group or Q′;
• Q′ has the same definition as that of Q;
• p is, each independently in each Q and Q′, an integer of 0-3, and the total sum of p is one or more in the formula (1);
• in Q, the number of Si atoms which are straightly linked via the Z group is up to five;
• k is, each independently in each unit in parentheses with the subscript β, an integer of 1-3;
• and
• α and β are, each independently, an integer of 1-9, and the sum of α and β is a valence of X.