Solvent-Independent Molecular Weight Determination of Polymers Based on a Truly Universal Calibration.

Diffusion-ordered NMR spectroscopy (DOSY) allows for accurate molecular weight calibration and determination that can be corrected for solvent influences. Polystyrene and poly(ethylene glycol) standards have been used to calibrate DOSY diffusion data for a variety of solvents, showing a high correlation of data when the bulk viscosity of the solvent is accounted for following the Stokes-Einstein equation. In this way, a type of universal calibration is introduced that allows for determinations of average molecular weight that are at least as accurate as those of traditional size-exclusion chromatography (SEC), if not better.

Encapsulation by Directed PISA: RAFT-Based Polymer-Vesiculated Pigment for Opacity Enhancement in Paint Films.

A novel method is demonstrated to encapsulate titanium dioxide pigment using directed polymerization-induced self-assembly (PISA) with reversible addition-fragmentation chain-transfer (RAFT) controlled emulsion polymerization. The polymerization is carried out in a batch process in which both styrene (Sty) and the pigment are emulsified using triblock amphiphilic macro-RAFT copolymers as stabilizers. RAFT-controlled chain growth leads to directed lamellar self-assembly, forming polystyrene (PS) shells' encapsulating pigment particles with 100% efficiency.