No abstract

No abstract

Block copolymers containing segments of poly(dimethylsiloxane) (PDMS) and polystyrene were synthesized. Dihydroxy terminated PDMS Mn 2500 g/mol, was reacted with an ali‐phatic diisocyanate (isophorone diisocyanate) and an aliphatic hydroperxide (t‐butyl hy‐droperoxide). The resulting polymeric peroxycarbamate having siloxane units (a new mac‐roinitiator) was used as free radical initiator for vinyl polymerization of styrene. Formation of block copolymers was illustrated by several characterization methods such as chemical and spectroscopic analysis, fractionation, and GPC. Mechanical and thermal characterization of the copolymers were made by stress–strain tests and DSC. The surface properties and the morphology of the block copolymers were investigated by contact angle measurements and SEM. © 1996 John Wiley & Sons, Inc.

No abstract

SYNOPSISa,@-Amine terminated organofunctional polydimethylsiloxane (PDMS) was condensed with 4,4'-azobis-4-cyanopentanoyl chloride (ACPC) to prepare macroazoinitiators containing siloxane units. Interfacial polycondensation reaction at room temperature was applied: ACPC was slightly dissolved in carbon tetrachloride and it was poured on aqueous NaOH solution of PDMS. Block copolymers containing PDMS as a block segment combined with polystyrene (PS) have been derived by the polymerization of styrene monomer initiated by these macroazoinitiators. PS-b-PDMS block copolymers were characterized by using nuclear magnetic resonance and infrared spectroscopy. Thermal and mechanical properties of the block copolymers were studied by using thermogravimetric analysis, differential scanning calorimetry, and a Tensilon stress-strain instrument. The morphology of block copolymers was investigated by scanning electron microscopy. PDMS-g-polybutadiene (PBd) graft copolymers were also prepared by reaction of PBd with the above macroazoinitiator. Increase in the amount of macroazoinitiator in the mixture of PBd (52% w/w) leads to the formation of crosslinked graft copolymers. Molecular weights of soluble graft copolymer samples were between 450 and 600 K with a polydispersity of 2.