Functional Materials and Biomaterials

This review article summarizes the synthetic efforts in constructing functional hyperbranched macromoleculesfrom acetylenic triple-bond building blocks. Polymerization reactions including polycoupling, polyadditionand polycyclotrimerization have been developed for the synthesis of new hyperbranched polymers such as polyynes,polyenes, polyarylenes and polytriazoles with novel topological structures and electronic conjugations.Polymers with high molecular weights (up to >1 × 10⁶) havebeen obtained in high yields (up to 100%). Whilst their linear counterparts are often intractable, thehyperbranched conjugated polymers are completely soluble in common organic solvents and are hence readilyprocessable by macroscopic techniques. The hyperbranched polymers exhibit an array of functional propertiesincluding strong light emission, stable optical nonlinearity and high photorefractivity. The polymers cangenerate fluorescent images, assemble into supramolecular patterns, and form well-aligned nanotubes. Thepolyynes can be post-functionalized through metal complexation, whose refractive indexes can be manipulatedto a great extent by photoirradiation. The hyperbranched polymer complexes can serve as precursorsto soft ferromagnetic ceramics and as catalysts for carbon nanotube fabrications.

This is to review viscoelastic properties of monomolecular layers of polymers on the air/water interface,as probed principally by surface light scattering. The method is a non-invasive one that makes useof spontaneous capillary waves, induced by density fluctuations within liquids under thermal equilibrium.The capillary waves are also called ripplons, and they propagate with temporal damping. The interface isdetermined to be molecularly smooth but still dielectric permittivity difference between air and water islarge enough to give rise to strong light scattering. Thus, the scattering amounts to a surface analogof Brillouin scattering in bulk liquid wherein spontaneously propagating phonons interact with light. Thus,the power spectra of scattered light from the interface provide the propagation rate and the damping coefficient.Analysis is based on the resonant mode-coupling of lateral and transverse waves that are recast into thelateral storage modulus and the corresponding loss modulus. By virtue of the two-dimensional characterof the monolayers, many intriguing observations have been made with respect to amphiphilic properties andchain architecture of homopolymers and copolymers. Close connection and correspondence between the staticproperties of polymer monolayers and their rheological behavior have been established, and the review coversreports over the past two decades.

Although extensive studies on copolymers have been carried out with a view to exploiting thecombined homopolymer properties, physical blends of polymers have warranted less attention. But as a resultof increased scientific and economic interest research in this challenging field has grown over the lasttwo decades. The unique properties of silicone polymers, due to their Si–O–Si backbone, includingtheir low Tg's, gives rise to some specific applications. However, it is their singular structure whichalso makes silicone polymers incompatible with most other macromolecules and limits their incorporationto low amounts. Bleeding and mechanical loss are observed at higher percentages. This overview is dividedinto three parts: the first covers silicone/polymer bicomponent blends with the silicone being either functionalizedor not. The second part describes the different ways to compatibilize the two phases of the silicon/polymerblend using copolymers which can be added as either preformed copolymers or synthesized in-situ. The efficiencyof the copolymers involved varies depending on their chemical structure and architecture. The final sectionis dedicated to the different methods of preparation of Interpenetrating Polymer Networks (IPNs) which arecommercially and industrially by far the most interesting. The relevant processes (extrusion, batch, casting,etc.) as well as the properties of the various resulting materials are also reviewed throughout the paper.

DNA has special properties and its unique double-helical structure offers excellent prospects forcreating novel DNA-based materials. In recent years, DNA has been shown to be an ideal molecule in thematerial world. This review is intended to provide an overview of functional materials derived from DNAbased on the double-helical structure. Various DNA-based materials are reviewed according to the basicDNA structural properties, including the electrostatic properties of DNA as a highly charged polyelectrolyte,complementary base pairing, and intercalation and groove binding interaction with small molecules. Finally,attempts to produce biomaterials based on DNA are also summarized.

This review consists of two major parts: recollection of advances in therapeutic cardiovascular biomaterialsand a summary of “H-bond grafting” methodology for biocompatible/biofunctional surfacemodification of blood-contact polyurethanes. The development of a H-bond grafting model as depictedin the second part is initiated with originality that is based on an understanding and rendering of advantagesextracted from the comprehensive investigations reviewed in the first part. The H-bond grafting strategyis invented via mimicking the buildup of hydrogen bond-based physical crosslinking points in elastomericpolyurethanes, by which the accordingly designed surface-modifying additives are anchored to the virtualinterface with the favor of a non-covalent mechanism and the talent of microenvironmental optimizationbetween biomaterials and the biological counterparts. This review assembles a series of self-containedtopics covering aspects from prototype setup through various blood-contacting assessments. As a platformof delivery, superior efficacies have been achieved from the H-bond grafting-modified polyurethane surfacestypically on albumin-selective binding, biocompatibility, and engineered endothelialization.