Data for: Versatile synthesis of siloxane-based graft copolymers with tunable grafting density

A versatile synthetic platform is reported that affords high molecular weight graft copolymers containing polydimethylsiloxane (PDMS) backbones and vinyl-based side chains with excellent control over molecular weight and grafting density. The synthetic approach leverages thiol–ene click chemistry to attach an atom-transfer radical polymerization (ATRP) initiator to a variety of commercially available poly(dimethylsiloxane-co-methylvinylsiloxane) (PDMS-co-PVMS), followed by controlled radical polymerization with a wide scope of vinyl monomers. Selective degradation of the siloxane backbone with tetrabutylammonium fluoride confirmed the controlled nature of side-chain growth via radical polymerization, yielding targeted side-chain lengths for copolymers containing up to 50% grafting density and overall molecular weights in excess of 1 MDa. In addition, by using a mixture of thiols, grafting density and functionality can be further controlled by tuning initiator loading along the backbone. For example, solid-state fluorescence of the graft copolymers was achieved by incorporating a thiol-containing fluorophore along the siloxane backbone during the thiol–ene click reaction. This simple synthetic platform provides facile control over the properties of a wide variety of grafted copolymers containing flexible PDMS backbones and vinyl polymer side chains.

Methods
Size-exclusion chromatography (SEC) was performed on a Waters Alliance HPLC system using two Tosoh TSKgel SuperHZM-N columns containing 3 µm crosslinked polystyrene beads and a Waters 2410 Differential Refractometer with chloroform with 0.25% triethylamine as the mobile phase at a 0.35 mL/min flow rate. Number and weight average molecular weights (Mn and Mw respectively) were calculated based on polystyrene standards to calculate dispersity (Ð), unless otherwise specified. Plotted data has been baseline-corrected and normalized. The dRI signal for SEC data in Figure 2 corresponding to the top two traces has been inverted to facilitate comparison with the bottom trace. 

1H nuclear magnetic resonance (NMR) spectroscopy was performed on a Varian 600 MHz using a relaxation delay (d1) of 4.8 seconds. 13C NMR spectroscopy was performed on a Bruker 500 MHz with a d1 of 10 seconds. Signal ppm values were shifted to match the solvent signal to 7.257 ppm in 1H and 77.17 ppm in 13C.

Differential Scanning Calorimetry (DSC) was performed on a TA instrument Q2000 DSC with three repeated cycles: heating from 25 °C to 150 °C, cooled to -150 °C, and heated to 150 °C. Only the final cycle is plotted. Glass transition values were calculated using a function in the Trios software.