Polymerizable polydimethylsiloxane-polyoxyalkylene block copolymers

A polymerizable polydimethylsiloxane-polyoxyalkylene block copolymer of formula (I)

• in which:
• n1 is an integer of from 5 to 50;
• t1 is an integer of from 1 to 15;
• X0 is O or NR′ in which R′ is hydrogen or C1-C4-alkyl;
• R″ is hydrogen or methyl;
• R1 and R2 independent of each other are a C1-C6 alkylene divalent radical or a C1-C6 alkylene-oxy-C1-C6 alkylene divalent radical;
• pOAlk is a divalent radical of formula (II)
• in which EO is an oxyethylene unit (—CH2CH2O—), PO is an oxypropylene unit of
• and BO is an oxybutylene unit of
• e1 is an integer of 5 to 100, p1 and b1 independent of each other are an integer of 0 to 50, provided that if (p1+b1)≥1, e1/(p1+b1)≥2;
• and if p1 and b1 both are zero and e1 is an integer of 10-100 hpL is a divalent radical of formula (III) or (IV)
• in which R3 and R4 independent of each other are a substituted or unsubstituted C1-C12 alkylene divalent radical, Ra is hydrogen or methyl, and Rb is hydrogen, C1-C3 alkyl, acetyl, or C2-C4 alkanoylamino which optionally has a carboxyl group,
• wherein the chain-extended polydiorganosiloxane vinylic crosslinker has a number-average molecular weight of at least 3000 Daltons.