Joshua W. Robinson

A versatile polypeptoid platform based on N-allyl glycine

N-Allyl glycine N-carboxyanhydride (NCA) was synthesized and polymerized by ring opening polymerization under homo- or heterophase conditions to afford well-defined polypeptoids (M(W) = 1.5-10.5 kg mol(-1), PDI = 1.1-1.4). Poly(N-allyl glycine) demonstrated stimuli-responsive behaviour in water and was readily modified via thiol-ene photochemistry under experimentally benign conditions.

Probing the molecular design of hyper-branched aryl polyesters towards lubricant applications

We report novel polymeric materials that may be used as viscosity index improvers (VII) for lubricant applications. Our efforts included probing the comb-burst hyper-branched aryl polyester architecture for beneficial viscosity and friction behavior when utilized as an additive in a group I oil. The monomer was designed as to undergo polymerization via polycondensation within the architectural construct (AB2), typical of hyperbranched polymers. The monomer design was comprised of aliphatic arms (12 or 16 methylenes) to provide the necessary lipophilicity to achieve solubility in a non-polar medium. Once polymerized, via catalyst and heat, the surface alcohols were functionalized with fatty acids (lauric and palmitic). Controlling the aliphatic nature of the internal arms and peripheral end-groups provided four unique flexible polymer designs. Changing the reaction time and concentration provided opportunities to investigate the influence of molecular weight and branching density on oil-solubility, viscosity, and friction. Oil-solubility was found to decrease with fewer internal carbons, but the number of internal carbons appears to have little influence on the bulk solution viscosity. At concentrations of 2 wt % in a group I base oil, these polymer additives demonstrated an improved viscosity index and reduced friction coefficient, validating the basic approach.

Dual functional star polymers for lubricants

Star-shaped poly(alkyl methacrylate)s (PAMAs) with a three arm architecture were designed, prepared and their performance as a dual additive (viscosity index improver and friction modifier) for engine oils was evaluated. Furthermore, the structure–property relationships between the macromolecular structure and lubricant performance were studied, such as molecular weight and polarity effects on the viscosity index. Several co-polymers of dodecylmethacrylate with polar methacrylates in various amounts and various topologies, were synthesized as model compounds. Star polymers with a polar content of at least 10% in a block or tapered block topology effectively reduced the friction coefficient in both mixed and boundary lubrication regimes. However, a polar content of 20% was efficient in reducing friction in both random and block topologies.