Synthesis and self-assembly of amphiphilic comb-copolymers possessing polyethyleneimine and its derivatives: Site-selective formation of loop-cluster covered vesicles and flower micelles

Crystalline lamellar films with honeycomb structure from comb-like polymers of poly(2-long-alkyl-2-oxazoline)s

Comb-like copolymers are usually structured by grafting polymeric side chains onto main polymer chain. There are few reports of comb-on-comb polymers in which dense secondary side chains are grafted onto primary side chain. In this work, we synthesized comb polymers with grafted-on-graft side chains (c-PEI-g-Acyl) via an effective acylation reaction of comb polymers possessing polyethyleneimine (PEI) side chain with long-alkyl acyl chlorides. For comparison, we also synthesized homopolymers l-PEI-g-Acyls via reaction of linear PEI with long-alkyl acyl chlorides. Then, we investigated their crystalline feature in the film formation by XRD, DSC and SEM, and found that the polymers tend to form hexagonal lamella structures with bilayer alkyl spacing. The comb polymers c-PEI-g-Acyls and linear polymers l-PEI-g-Acyls were used in preparation of honeycomb film by the "breath-figure" process by dropping chloroform solution of the polymers on substrate. Different to many honeycomb polymeric films which are supported by amorphous phase, interestingly, our polymers easily afford honeycomb films which are supported by crystalline lamellae frames under higher humidity condition. It was found that the comb polymers of c-PEI-g-Acyls with longer PEI primary side chain and long alkyl secondary side chain have advantages in producing honeycomb film than linear polymers of l-PEI-g-Acys.

Cationic polymeric template-mediated preparation of silica nanocomposites

Biosilicification allows the formation of complex and delicate biogenic silica in near-neutral solutions under ambient conditions. Studies have revealed that, during biosilicification, basic amino acid residues and long-chain polyamines of organic substrates interact electrostatically with negatively charged silicate precursors in solution, catalyzing the polycondensation of silicic acid and accelerating the formation of silica. This mechanism has inspired researchers to explore polymers bearing chemical similarity with these organic matrices as cationic templates for biomimetic silicification. Such templates can be classified into two general categories based on the physical forms applied. One is a solution of water-soluble cationic polymers, either natural or synthetic, used as is for silicification. The other category includes various microscopically shaped entities made of cationic polymer-containing molecules, in the form of micelles, vesicles, crystalline aggregates, latex particles, and microgels. Combined with controlled polymerization and other techniques, these preorganized templates can be tailor designed in terms of sizes and morphologies to allow further expansion of properties and functions. In this review, notable research progress for both categories of silicification under biomimetic conditions is discussed. With the merits of silica and cationic polymers seamlessly integrated, the potential of such versatile nanocomposites in biomedical as well as energy and environmental applications is also briefly highlighted.

Poly ethylene glycol (PEG)-Related controllable and sustainable antidiabetic drug delivery systems

Diabetes mellitus is one of the most challenging threats to global public health. To improve the therapy efficacy of antidiabetic drugs, numerous drug delivery systems have been developed. Polyethylene glycol (PEG) is a polymeric family sharing the same skeleton but with different molecular weights which is considered as a promising material for drug delivery. In the delivery of antidiabetic drugs, PEG captures much attention in the designing and preparation of sustainable and controllable release systems due to its unique features including hydrophilicity, biocompatibility and biodegradability. Due to the unique architecture, PEG molecules are also able to shelter delivery systems to decrease their immunogenicity and avoid undesirable enzymolysis. PEG has been applied in plenty of delivery systems such as micelles, vesicles, nanoparticles and hydrogels. In this review, we summarized several commonly used PEG-contained antidiabetic drug delivery systems and emphasized the advantages of stimuli-responsive function in these sustainable and controllable formations.