Preparation and Characterization of H-Shaped Polylactide.

An H-polymer has an architecture that consists of four branches symmetrically attached to the ends of a polymer backbone, similar in shape to the letter "H". Here, a renewable H-polymer efficiently synthesized using only ring-opening transesterification is demonstrated. The strategy relies on a tetrafunctional poly(±-lactide) macroinitiator, from which four poly(±-lactide) branches are grown simultaneously.

Cylinders-in-Undulating-Lamellae Morphology from ABC Bottlebrush Block Terpolymers.

Block polymer self-assembly affords a versatile bottom-up strategy to develop materials with the desired properties dictated by specific symmetries and dimensions. Owing to distinct properties compared with linear counterparts, bottlebrush block polymers with side chains densely grafted on a backbone have attracted extensive attention. However, the morphologies found in bottlebrush block polymers so far are limited, and only lamellar and cylindrical ordered phases have been reported in diblock bottlebrushes.

Impact of Macromonomer Molar Mass and Feed Composition on Branch Distributions in Model Graft Copolymerizations.

Graft polymers are useful in a versatile range of material applications. Understanding how changes to the grafted architecture, such as the grafting density (), the side-chain degree of polymerization (), and the backbone degree of polymerization (), affect polymer properties is critical for accurately tuning material performance. For graft-through copolymerizations, changes to and are controlled by the macromonomer degree of polymerization () and the initial fraction of the macromonomer in the feed (), respectively.

Improving the adhesion, flexibility, and hemostatic efficacy of a sprayable polymer blend surgical sealant by incorporating silica particles.

Commercially available surgical sealants for internal use either lack sufficient adhesion or produce cytotoxicity. This work describes a surgical sealant based on a polymer blend of poly(lactic-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) that increases wet tissue adherence by incorporation of nano-to-microscale silica particles, without significantly affecting cell viability, biodegradation rate, or local inflammation. In functional studies, PLGA/PEG/silica composite sealants produce intestinal burst pressures that are comparable to cyanoacrylate glue (160 mmHg), ∼2 times greater than the non-composite sealant (59 mmHg), and ∼3 times greater than fibrin glue (49 mmHg).