Novel triblock siloxane copolymers: Synthesis, characterization, and their use as surface modifying additives

Abstract

SynopsisSynthesis of novel triblock, polycaprolactone-b-polydimethylsiloxane (PDMS) and poly(2ethyl-oxazoline)-b-PDMS copolymers were demonstrated. These materials were obtained via the ring-opening polymerization of c-caprolactone or 2-ethyl-2-oxazoline monomers by using organofunctionally terminated PDMS oligomers as initiators and comonomers. Segment molecular weights in these copolymers were varied over a wide range between lo00 and 2oooO g/mol and the formation of copolymers with desired backbone compositions were monitored by 'H-NMR spectroscopy and GPC. DSC and TMA studies showed the formation of two phase morphologies with PDMS (Tg, -120°C) and polycaprolactone (Tm, 50-60°C) or poly(2-ethyl-2-oxazoline) (Tgr 40-60°C) transitions respectively. The use of polycaprolactone-b-PDMS copolymers as surface modifying additives in polymer blends were also investigated. When these copolymers were blended at low levels (0.25-10.0% by weight) with various commercial resins such as, polyurethanes, PVC, PMMA, and PET, the resulting systems displayed silicone-like, hydrophobic surface properties, as determined by critical surface tension measureIl,ents or water contact angles. The effect of siloxane content, block length, base polymer type and morphology on the resulting surfaces are discussed.

High conductivity of defect doped polymers in metal–polymer–metal systems

“…At a small doping level the temperature dependence of conductivity corresponds to hopping transport where the activation energy depends on the doping concentration. At an intermediate doping level the transport obeys the variable range hopping laws at low temperatures similar to the behavior of doped semiconductors with an impurity concentration corresponding to the dielectric side of the metal-insulator transition, whereas at high doping levels the conductivity may be of metallic type with a maximum absolute value of conductivity up to 10 5 S/cm. In regard to non-conjugated polymers there is the common opinion that all of them have good dielectric properties only at electric fields less than the breakdown field (E c ).…”

“…Copolymer [co-poly[4,4′-bis(4″-N-phenoxy) diphenyl-sulfone-α,ω-bis (γ-amino propyl)oligodimethylsiloxane]imide of 1,3-bis(3′,4-dicarboxyphenoxy)benzene] (Fig. 2) has been synthesized in accordance with the method of a single-stage high temperature imidization in solution in N-methylpyrrolidone -toluene mixture which was described in [10].…”

Improved adhesion of silicone rubber to polyurethane by induced surface reconstruction

“…The inherently hydrophobic nature of silicones, coupled with their ability to segregate to the surface, facilitates their use as a surface modifier for other materials. This property has been exploited in the preparation of silicone-modified polyesters 4 ; the synthesis of polydimethylsiloxane (PDMS) and polystyrene copolymers 5 ; polyimidesiloxane segmented copolymers 6 ; triblock siloxane copolymers used as surface modifying additives 7 ; blood-compatible polyurethane (PU)-polysiloxane graft copolymers 8 ; and the surface treatment of fumed silica for use as antifoaming compounds. 9 Small amounts of the copolymers (ca.…”

“…1% by weight) could be added to different polymers to alter their surface properties. The air-polymer surface of the resulting polymer system is usually dominated by the low surface-energy siloxane, 7,10 preventing adhesion to polar materials. This phenomenon of surface segregation of a component with a low surface energy in multicomponent polymeric materials attracts attention to the analysis of polymer surfaces and the modifications of their properties.…”

Surface properties and depth analysis of polyethylene/polydimethylsiloxane composite prepared by using supercritical carbon dioxide

“…It is also widely known owing to its extremely low glass transition temperature, flexibility and hydrophobic surface properties. [5][6][7][8] These properties of PDMS make it suitable for use in different industries. [9][10][11][12][13] Several studies have been reported on the phase behavior of PE/PDMS composites.…”