Styrene polymerization with a macroinitiator having siloxane units

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.

Heat‐triggered poly(siloxane‐urethane)s based on disulfide bonds for self‐healing application

“…The soft PDMS segments have weak tensile strength due to the molecular structure. The interaction between the silicones molecular is very weak, because the polarities of the siloxane bonds is offset from each other in the ordered molecular structure of the helical crimp of the linear polysiloxane . And the nonpolar groups are arranged in the outer side of the spiral of the main chain of silicon, the polarity of the silicone bonds from the shield effect, so the entire polysiloxane molecular showed nonpolar, intermolecular force is weak, showing low cohesive energy density, so the mechanical property of silicone is poor .…”

Peroxide‐Grafted PDMS: Hydrosilylation Reaction and Thiol‐Ene Chemistry as an Alternative Pathway

“…with R being the gas constant (8.314 J Á mol À1 Á K À1 ), and T the temperature in K.Combining Equations (1), (2) and (3) gives…”

“…For example, ''azo groups'' were inserted by condensation of azobis(cyanopentanoyl) chloride with amino-terminated polysiloxane, [1] and peroxycarbamate groups were introduced by the reaction between dihydroxy terminated polysiloxane and an aliphatic hydroperoxide. [2] Bis(silyl pinacolate) groups were inserted in a polydimethylsiloxane (PDMS) backbone by hydrosilylation of a vinyl-functional silane containing a pinacolic entity with an hydrogen terminated polydimethylsiloxane. [3,4] Some authors introduced thiuram disulfide groups by addition of CS 2 to an a-(secondary amine)-terminated PDMS followed by the addition of a coupling agent (I 2 ).…”

Syntheses of triblock polybutadiene–polydimethylsiloxane copolymers by coupling reactions

“…Besides anionic polymerization, the free‐radical vinyl polymerization of styrene (ST) initiated by macroinitiators based on peroxycarbamate‐terminated PDMS has been reported;12 it yielded diblock PST–PDMS copolymers. Another macroinitiator of this type was prepared by a condensation reaction between 4,4′‐azobis‐4‐cyanopentanoyl chloride, PDMS, and methacroyl chloride 13…”