A rapid and efficient approach for the preparation and modification of a versatile class of functional polymer nanoparticles has been developed, for which the entire engineering process from small molecules to polymers to nanoparticles bypasses typical slow and inefficient procedures, and rather employs a series of steps that capture fully the “click” chemistry concepts that have greatly facilitated the preparation of complex polymer materials over the past decade. The construction of various nanoparticles with functional complexity from a versatile platform is a challenging aim to provide materials for fundamental studies and also optimization toward a diverse range of applications. In this paper, we demonstrate the rapid and facile preparation of a family of nanoparticles with different surface charges and functionalities based on a biodegradable polyphosphoester block copolymer system. From a retrosynthetic point of view, the non-ionic, anionic, cationic and zwitterionic micelles with hydrodynamic diameters between 13 nm to 21 nm and great size uniformity were quickly formed by suspending, independently, four amphiphilic diblock polyphosphoesters into water, which were functionalized from the same parental hydrophobic-functional AB diblock polyphosphoester by “click” type thiol-yne reactions. The well-defined (PDI < 1.2) hydrophobic-functional AB diblock polyphosphoester was synthesized by an ultrafast (< 5 min) organocatalyzed ring-opening polymerization in a two-step, one-pot manner with the quantitative conversions of two kinds of cyclic phospholane monomers. The whole programmable process starting from small molecules to nanoparticles could be completed within 6 h, as the most rapid approach for the anionic and non-ionic nanoparticles, although the cationic and zwitterionic nanoparticles required ca. 2 days due to purification by dialysis. The micelles showed high biocompatibility, with even the cationic micelles exhibiting a 6-fold lower cytotoxicity toward RAW 264.7 mouse macrophage cells, as compared to the Lipofectamine® commercial transfection agent.

Saccharides, based on their wide bioavailability, high chemical functionality and stereochemical diversity, are attractive starting materials for the development of new synthetic polymers. Established carbonylation methodologies were used to synthesize a 5-membered cyclic carbonate monomer, 4,6-O-benzylidene-2,3-O-carbonyl-α-d-glucopyranoside (MBGC), in high yield (>95%) from a commercially available d-glucopyranoside derivative. The ability of this monomer to undergo ring-opening polymerization (ROP) with a range of organocatalysts, rather than the previously reported anionic initiators, was investigated. These new conditions were developed to widen the functional group tolerance in the polymerization, and achieve better control over the final properties of the polymers. The most promising of the catalysts examined, 1,5,7-triazabicyclo[4.4.0]­dec-5-ene (TBD), was used in a kinetic study to confirm the well-controlled nature of the ROP. Optimized conditions were then successfully applied to the synthesis of polymers of different molecular weights. Two post-polymerization modifications were completed via the removal of the benzylidene acetal protecting group to release a water-soluble poly­(glucose carbonate), and then addition of acetyl groups to facilitate characterization studies. MALDI-TOF MS analysis was performed to further probe the chemistry of the polymerization and deprotection. A wide range of thermal decomposition temperatures (233–347 °C), glass transition temperatures (87–233 °C), and water contact angles (38–128°) was achieved by this series of polymers. The hydrolytic degradability of these polymers was also examined, demonstrating differing degradation mechanisms based on the acidic vs. basic conditions used. Consequently, this single monomer was successfully employed in the straightforward synthesis of a polymeric system with tunable properties based on the molecular weight and repeat unit composition.

A liquid crystalline elastomer incorporating a mesogenic derivative of the 2,6-bisbenzimidazolylpyridine (Bip) ligand has been prepared, and its shape memory and actuating properties have been studied. The reversible liquid crystal to isotropic transition is utilized as the switching mechanism for these stimuli-responsive materials. As such, this material exhibits soft shape memory; that is, flexibility is retained in both the permanent and temporary shapes. In addition to the thermal shape memory/actuating properties exhibited by most liquid crystalline elastomers, the incorporation of the metal ion-binding Bip mesogen into the backbone of the network imparts both (i) photoresponsive properties, via a photothermal conversion process, and (ii) metal-ion-triggered shape recovery/actuation to the material. For the latter process, it is proposed that the metal-binding event induces liquid crystalline to isotropic transition in this material at room temperature, resulting in actuation/recovery of the permanent shape.

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Strategies for the preparation of polycarbonates, derived from the natural product d-glucose, which have the potential to degrade back into their bioresorbable starting material and CO2, were developed. By employing established carbohydrate protection/deprotection chemistries, two d-glucose derivatives, methyl 4,6-O-benzylidene-α-d-glucopyranoside or methyl α-d-glucopyranoside, were converted into four different regioisomeric diol monomers, i.e., 1,4-, 1,6-, 2,6-, or 3,6-diols, as confirmed by nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and mass spectrometry. Each type of regioisomeric monomer was then employed in a condensation polymerization with phosgene, generated in situ from triphosgene, as a comonomer, in the presence of pyridine, to produce four types of polycarbonates with different backbone regio-connectivity, as characterized by size exclusion chromatography, NMR spectroscopy, and IR spectroscopy. Interestingly, their thermal properties, i.e., glass transition temperature (T g) and thermal degradation behavior, were tunable by changing the topological composition of the monomeric unit. That is, polycarbonates with 2,6- and 3,6-backbone connectivity resulted in significantly higher T g of ca. 85 and 83 °C, respectively, as compared to those with 1,4- and 1,6-backbone connectivity, showing a T g of ca. 33 °C, as measured by differential scanning calorimetry. Furthermore, when the thermal decomposition temperature was measured by thermogravimetric analysis, the nonanomeric carbon backbone-based polycarbonates (2,6- and 3,6-) exhibited higher thermal stability and a sharper decomposition profile, with onset decomposition temperature (T d,onset) at 363 or 336 °C, as compared with those polymers containing the anomeric carbon in the carbonate linkage (1,4- and 1,6-), having T d,onset at 171 and 163 °C.