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

Synthesis of novel triblock, polycaprolactone‐b‐polydimethylsiloxane (PDMS) and poly(2‐ethyl‐oxazoline)‐b‐PDMS copolymers were demonstrated. These materials were obtained via the ring‐opening polymerization of ϵ‐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 1000 and 2000 g/mol and the formation of copolymers with desired backbone compositions were monitored by 1H‐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) (Tg, 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 measurements or water contact angles. The effect of siloxane content, block length, base polymer type and morphology on the resulting surfaces are discussed.