A new functional dilactone, 3-(2-propynyl)-1,4-dioxane-2,5-dione (4), was synthesized from ethyl glyoxalate and propargyl bromide via a 4-step reaction sequence. Ring-opening (co)polymerisation of the alkyne-functionalised monomer 4 with L-lactide was carried out in dichloromethane at 30 °C using N,N-dimethylaminopyridine as a catalyst and benzyl alcohol as an initiator. The resulting alkyne-functionalised copolyesters were characterized by ¹H NMR, size exclusion chromatography (SEC) and MALDI-TOF spectroscopy. Azide end-functionalised PEG was then grafted onto the polyester backbone with multiple pendant alkyne moieties using copper-catalysed azide–alkyne cycloaddition (click chemistry). The graft copolymers were characterized by ¹H NMR, SEC and DOSY NMR. The aggregation behavior of the copolymers in water was investigated by fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The critical aggregation concentration was in the range of 10–50 mg L⁻¹. The nano-sized objects were rod-like in shape with a diameter of 100 nm and a length of around 400 nm.

A simple method for the synthesis of a family of poly(ε-caprolactone)-g-polyethylene glycol (PCL-g-PEG) copolymers of controlled amphiphilicity and their use in generating nanospheres or micelles are reported. PCL-g-PEGs with various compositions are prepared from a single strategy relying on a combination of post-polymerization modification and subsequent thiol–yne photografting. Alkyne-functional PCL (PCL-yne) was first obtained by anionic activation and reaction with propargyl bromide to yield PCL-yne with 8% alkyne groups. PEG-thiol is then reacted on PCL-yne under UV activation to yield the targeted graft copolymer by thiol–yne photoaddition. The advantage of the approach is that control over the composition is easily achieved, yielding amphiphilic graft copolymers with ethylene glycol/caprolactone (EG/CL) ratios ranging from 0.1 to 1.3. Starting from this single strategy, it was therefore possible to obtain nanospheres (D_H ∼ 55 nm) or micelles (D_H ∼ 30 nm) by copolymer self-assembly depending on the EG/CL ratio. The potential of PCL-g-PEG micelles as drug carriers was finally evaluated with curcumin that was efficiently encapsulated, protected and released over 80 days. Interestingly it was found that drug encapsulation efficiency and drug loading were higher for PCL-g-PEG copolymers compared to block PCL-b-PEG.

A series of poly(ethylene glycol)–polylactide–poly(ethylene glycol) (PEG–PLA–PEG) triblock copolymers with symmetric or asymmetric chain structures were synthesized by combination of ring-opening polymerization and copper-catalyzed click chemistry. The resulting copolymers were used to prepare self-assembled aggregates by dialysis. Various architectures such as nanotubes, polymersomes and spherical micelles were observed from transmission electron microscopy (TEM), cryo-TEM and atomic force microscopy (AFM) measurements. The formation of diverse aggregates is explained by modeling from the angle of both geometry and thermodynamics. From the angle of geometry, a “blob” model based on the Daoud–Cotton model for star polymers is proposed to describe the aggregate structures and structural changes with copolymer composition and molar mass. In fact, the copolymer chains extend in aqueous medium to form single layer polymersomes to minimize the system's free energy if one of the two PEG blocks is short enough. The curvature of polymersomes is dependent on the chain structure of copolymers, especially on the length of PLA blocks. A constant branch number of aggregates (f) is thus required to preserve the morphology of polymersomes. Meanwhile, the aggregation number (N_agg) determined from the thermodynamics of self-assembly is roughly proportional to the total length of polymer chains. Comparing f to N_agg, the aggregates take the form of polymersomes if N_agg ≈ f, and change to nanotubes if N_agg > f to conform to the limits from both curvature and aggregation number. The length of nanotubes is mainly determined by the difference between N_agg and f. However, the hollow structure becomes unstable when both PEG segments are too long, and the aggregates eventually collapse to yield spherical micelles. Therefore, this work gives new insights into the self-assembly behavior of PEG–PLA–PEG triblock copolymers in aqueous solution which present great interest for biomedical and pharmaceutical applications.

We report a multi-stimuli responsive polymeric sensor consisting of a pseudorotaxane-like architecture fabricated from a 1,5-diaminonaphthalene end-functionalized poly(N-isopropyl)acrylamide (Napht-N-PNIPAM) and cyclobis(paraquat-p-phenylene) (CBPQT4+, 4Cl−). The coloured nature of the poly-pseudorotaxane provides a sensor for temperature and pH in water with an associated visible readout. To create this dual responsive polymeric sensor, a new chain transfer agent (Napht-N-CTA) incorporating a pH-responsive 1,5-diaminonaphthalene unit was synthesized and used for the polymerization of N-isopropylacrylamide via Reversible Addition-Fragmentation Chain Transfer (RAFT). The ability of Napht-N-PNIPAM to form a pseudorotaxane architecture with CBPQT4+, 4Cl− in aqueous media was studied by means of UV–Vis, NMR (1H, 2D-ROESY, DOSY) and ITC experiments. Interestingly, the pseudorotaxane architecture can be reversibly dissociated upon either heating the sample above its cloud point or protonating the nitrogen atoms of the 1,5-diaminonaphthalene-based guest unit by adjusting the pH to around 1. In both cases a dramatic colour change occurs from intense blue-green to colourless