Polysaccharide-based microgels are effective vectors for biopharmaceutics delivery and functional components in tissue engineering due to their bioactivity and biocompatibility. Currently, the synthesis of chemically crosslinked microgels typically requires long reaction times, high energy input and are low yielding due to low volumes of water phase used. Herein, we report the synthesis of norbornene-derivatized chitosan (CS-nbn-COOH), which can undergo rapid gelation in the presence of a thiolated crosslinker through the highly efficient thiol-ene photoclick reaction. This water-soluble photocrosslinkable derivative, synthesized on scale via a single step

Well-defined dendronized polymers (denpols) bearing high-generation dendron are attractive nano-objects as high persistency provides distinct properties, contrast to the random coiled linear polymers However, their syntheses via graft-through approach have been very challenging due to their structural complexity and steric hindrance retarding polymerization. Here, we report the first example of the synthesis of poly(norbornene) (PNB) containing ester dendrons up to the sixth generation (G6) by ring-opening metathesis polymerization. This is the highest generation ever polymerized among dendronized polymers prepared by graft-through approach, producing denpols with molecular weight up to 1960 kg/mol. Combination of size-exclusion chromatography, light scattering, and neutron scattering allowed a thorough structural study of these large denpols in dilute solution. A semiflexible cylinder model was successfully applied to represent both the static and dynamic experimental quantities yielding persistent length ( l p ), cross-sectional radius ( R cs ), and contour length ( L ). The denpol persistency seemed to increase with generation, with l p reaching 27 nm (Kuhn length 54 nm) for PNB-G6, demonstrating a rod-like conformation. Poly(endo-tricycle[4.2.2.0]deca-3,9-diene) (PTD) denpols exhibited larger persistency than the PNB analogues of the same generation presumably due to the higher grafting density of the PTD denpols. As the dendritic side chains introduce shape anisotropy into the denpol backbone, future work will entail a study of these systems in the concentrated solutions and melts.

We investigate the conformation of well-defined dendronized polymers (denpols) based on poly­(norborene) (PNB) and poly­(endo-tricycle­[4.2.2.0]­deca-3,9-diene) (PTD) backbones employing static and dynamic light scattering. Their synthesis by ring-opening metathesis polymerization (ROMP) led to fully grafted and high molecular weight denpols with narrow polydispersity. In dilute solutions, the persistence lengths were estimated by static (radius of gyration) and dynamic (translational diffusion) chain conformational properties of the denpols and were compared to their homologue precursor PNB. The conformation of denpols with a third generation side dendron conforms to a semiflexible chain with a persistence length of about 6–8 nm, virtually independent of the contour length. In the semidilute regime, the thermodynamics and cooperative diffusion of denpols resemble the behavior of the precursor solutions as described by the scaling theory of flexible polymers above the crossover concentration. The assumption of extremely high chain rigidity for this class of polymers is clearly not supported, at least for the third generation dendron.

The self-assembly in water of an amphiphilic P(nBMA(50%) -stat-DMAEMA(50%) )(100)-b-PDMAEMA(235) diblock copolymer based on hydrophilic dimethylaminoethylmethacrylate (DMAEMA) units and hydrophobic n-butylmethacrylate (nBMA) ones is reported. DMAEMA units have been incorporated into the hydrophobic block of this copolymer to moderate its hydrophobic character. Light scattering experiments revealed the formation of micelles whose apparent aggregation number varied reversibly with the ionization degree of the DMAEMA units. Incorporating hydrophilic units into the hydrophobic block of an amphiphilic block copolymer is thus a way to generate dynamic aggregates in aqueous medium. As this strategy was also successful using other types of hydrophilic units, we believe it to be universal.