abstract |
A hydrogen-functional silylated polymethylsilsesquioxane that contains no morenthan 0.12 residual silanol per Si atom and is obtained by silylating the silanol in startingnpolymethylsilsesquioxane. The starting polymethylsilsesquioxane has a predetermined numbernaverage molecular weight, Mn, from 380 to 2,000 and is represented by the general formulan (CH 3 SiO 3/2 ) n (CH 3 Si(OH)O 2/2 ) m nwherein m and n are positive numbers that provide the predetermined Mn, with the proviso thatnthe value of m /( m + n ) is less than or equal to 0.152/(Mn × 10 -3 ) + 0.10 and greater than or equalnto 0.034/(Mn × 10 -3 ). The hydrogen-functional silylated polymethylsilsesquioxane has thenformulan (CH 3 SiO 3/2 ) n (CH 3 Si(OH)O 2/2 ) m-k (CH 3 Si(OSiR 1 R 2 R 3 )O 2/2 ) k nwherein k is a positive number smaller than m , ( m - k )/( m + n ) is less than or equal ton0.12, and R 1 , R 2 , and R 3 are each selected from substituted and unsubstituted monovalentnhydrocarbon groups with the proviso that at least 1 of said R 1 , R 2 , and R 3 is hydrogen. |