Microdomain structures and phase transitions of binary and ternary mixtures of polystyrenepolyisoprene-polystyrene (PS-PI-PS) triblock copolymer Vector 4111 (containing 18% PS) and the corresponding homopolymers were investigated in thin films by atomic force microscopy and in bulk by small-angle X-ray scattering. The neat copolymer shows a hexagonally packed cylinder structure. The addition of PI homopolymer caused a transition from the cylindrical to a spherical microdomain structure via a biphasic intermediate state with coexisting cylindrical and spherical domains for both thin films and bulk. In contrast, addition of a small amount (14 wt %) of minority-component PS homopolymer in a mixture leads to a significant increase of the cylindrical microdomain curvature in thin films. The influence of the added homopolymer PS on the structure of bulk samples is discussed. Addition of equal amounts of both components together does not change the cylindrical structure for bulk or thin film samples but results in an aligned cylindrical microdomain structure observed for thin films. Interdomain distances decreased upon addition of small or moderate amounts (7-38 wt %) of either or both homopolymer.

RAFT aqueous emulsion polymerization of hydroxybutyl methacrylate using a poly(glycerol monomethacrylate) precursor leads to diblock copolymer spheres, worms or vesicles. A pseudo-phase diagram is constructed and the vesicles are briefly evaluated as a Pickering emulsifier.

Polyesters, as they exist in planta , are promising materials with which to begin the development of “green” replacements. Cutin and suberin, polyesters found ubiquitously in plants, are prime candidates. Samples enriched for plant polyesters, and in which their native backbones were largely preserved, were studied to identify “natural” structural features; features that influence critical physical properties. Quantitative nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and X-ray scattering methods were used to quantify structure–property relationships in these polymeric materials. The degree of esterification, namely, the presence of acylglycerol linkages in suberin and of secondary esters in cutin, and the existence of mid-chain epoxide groups defining the packing of the aliphatic chains were observed. This packing determines polymer crystallinity, the resulting crystal structure, and the melting temperature. To evaluate the strength of this rule, tomato cutin from the same genotype, studying wild-type plants and two well-characterized mutants, was analyzed. The results show that cutin’s material properties are influenced by the amount of unbound aliphatic hydroxyl groups and by the length of the aliphatic chain. Collectively, the acquired data can be used as a tool to guide the selection of plant polyesters with precise structural features, and hence physicochemical properties.

Judicious control over the mean degree of polymerization of each block in a amphiphilic diblock copolymer ensures that the corresponding worm gel exhibits thermoreversible (de)gelation behavior, as judged by TEM, SAXS and rheology studies.

Back Cover: A novel approach for producing more uniform, intact beads by electrospinning a self‐assembled block copolymer (BCP) solution is demonstrated. This approach allows a relatively high polymer concentration to be used, yet with a low degree of entanglement between polymer chains due to microphase separation of the BCP in a selective solvent system. Further details can be found in the article by L. Wang,* P. D. Topham, O. O. Mykhaylyk, H. Yu, A. J. Ryan, J. P. A. Fairclough, and W. Bras on page 1437.