An amphiphilic block copolymer of poly(ethylene oxide)-b-poly((N-methacryloxy phthalimide)-co-(7-(4-vinyl-benzyloxyl)-4-methylcoumarin)) (PEO45-b-P(MAPI36-co-VBC4)) is designed to improve the micellar stability during the photo-triggered release of hydrophobic cargoes. Analysis of absorption and emission spectra, solution transmittance, dynamic light scattering, and transmission electron microscopy supports that polymer micelles of PEO45-b-P(MAPI36-co-VBC4) upon the combinational irradiation of 365 and 254 nm light can be solubilized through the photolysis of phthalimide esters and simultaneously crosslinked via the partially reversible photo-dimerization of coumarins. The photo-triggered release experiment shows that the leakage of doxorubicin molecules from crosslinked micelles can be predictably regulated by controlling the irradiation time of 365 and 254 nm light.

Amphiphilic random copolymer micelle of P(NVP-co-NHPM) that responds to both UV and NIR light was designed and investigated. N-hydroxyphthalimide methacrylate—bearing a photoacid generator functional group was synthesized and used to construct the hydrophobic segment of P(NVP-co-NHPM); the N–O bond can be photocleaved when exposing the polymer aqueous solution to 310 nm UV light irradiation, inducing the micellar dissociation and delivery of loaded substances. Dynamic light scattering (DLS), atomic force microscope (AFM), and transmission electron microscopy (TEM) were used to characterize the micellar dissociation and controlled release processes. Moreover, the upconverting nanoparticles (NaLuF4:Gd/Yb/Tm) that can effectively absorb NIR light and convert it into visible and UV light were coloaded into polymer micelles to activate the micellar dissociation and the delivery of loaded cargoes via 980 nm NIR light.

The amphiphilic block copolymer poly(ethylene oxide)-b-poly(N,N′-dihydroxypyromellitimide-hexamethylene diisocyanate) (PEO-b-PNH) with photocleavable N–O urethanes has been prepared to investigate the photodegradation of the hydrophobic main chain and therefore the disruption of copolymer micelles. Measurements of absorption and emission spectra, optical transmittance, DLS analysis, and TEM observations were applied. It was shown that PEO-b-PNH could self-assemble into flower compound micelles in water. The photodegradation of the hydrophobic polyurethane within the micellar core upon irradiation with 365 nm light could be conveniently controlled by changing the irradiation intensity; furthermore, complete micellar disruption could be achieved when 42% of N–O urethanes were photocleaved. By using DOX as the hydrophobic guest, the drug release profile showed a linear leakage of DOX out of the swelling polymer micelles in the initial stage and thereafter a much more quick exponential decay of DOX precipitation because of the micellar disruption upon further irradiation. The diffusion experiment of the leaked DOX into buffer solution (pH 7.4) showed that the DOX leakage could be prominently accelerated by a very short time of 365 nm irradiation, indicating that the N–O photocleavage can serve as a “turn-on” switch for the release of DOX in aqueous media.

A betaine-type styrene monomer with the quaternary ammonium-borate anion inner-salt pair was synthesized through the quaternization reaction and polymerized to afford the target polybetaine of poly(4-vinylbenzyl methyl-diethanol ammonium borate) (PVMAB). The chemical structures of the monomer and polymer were well demonstrated with 1H-NMR and 11B-NMR spectra analysis. The thermal-sensitive experiment showed that PVMAB in water afforded gradually welldefined sigmoidal transmittance-temperature (T-t) curves along with the increasing polymer concentration. However, the phase transition temperatures at the bottom of the S-shaped curves were always below 10 °C due to the very weak zwitterionic association of the ammonium-borate inner-salt pairs. The UCST phase transition could also be tuned by changing the ethanol content in the ethanol/water mixture. And the cytotoxicity experiment demonstrated the good biomimetic property of PVMAB. This study enriches the toolbox of polybetaines by introducing the quaternary ammonium-borate anion zwitterionic pair in the repeat units, therefore broadens the scope of synthetic polybetaines.

The photo-dimerization characteristics of coumarin pendants within amphiphilic random copolymer micelles in aqueous solution was comprehensively investigated using various selected wavelength light in the UV-Vis-NIR region. The time-dependent photo-dimerization degree (PD) changes in the photo-dimerization experiments showed saturating behaviors with intensity-independent of PDmax values at 28%, 44%, 92%, 85%, 36%, 35%, 32% and 31% for 254, 288, 320, 360, 400, 500, 650 and 900 nm irradiations, respectively. The irradiation experiments at 254 and 288 nm announced the occurring of an asymmetric equilibrium of photo-dimerization and photo-cleavage at the used conditions. Both the alternative irradiation cycles of 360 and 254 nm, 650 and 254 nm showed a partially, but evidently reversible photo-dimerization tendency.

The water-soluble amphiphilic random copolymer of P(DMA-co-VBC) with coumarin pendants has been designed to investigate the photo-induced dynamic association of coumarin pendants within polymer micelles in aqueous solution. Methods of absorption and emission spectra, solution transmittance, dynamic light scattering (DLS), and atomic force microscope (AFM) were applied. It was found that P(DMA-co-VBC) can form polymer micelles in aqueous solution. The time-dependent photo-dimerization degree (PD) of polymer micelles upon different intensity irradiations of 320 nm light showed saturating behaviors with an intensity-independent value of the maximum photo-dimerization extent, while the maximum photo-cleavage extent of coumarin dimers declined with the increasing intensity of 254 nm irradiation at used conditions. Furthermore, a significant emission band at 445 nm (I2) evidently emerged as against the disappearance of emission band at 385 nm (I1) during the photo-dimerization, and the time-dependent I2/I1 ratios of polymer aqueous solution upon alternative irradiations of 320 and 254 nm light showed a wave-like increase as a function of irradiation cycles, indicating a wavy closeness of coumarin pendants within polymer micelles during the reversible photo-dimerization cycles.

The amphiphilic random copolymer of P(NVP-co-NHPSS) with photocleavable N–O sulfonate side groups has been prepared to investigate the light-triggered disruption of copolymer micelles. Methods of absorption and emission spectra, solution transmittance, dynamic light scattering (DLS), and transmission electron microscopy (TEM) were applied. It was found that P(NVP-co-NHPSS) could form polymeric nanoaggregates in aqueous solution. And the photocleavage of the N–O bond within copolymer micelles upon 365 nm UV light could be conveniently controlled by changing the irradiation intensity, leading to the disruption of copolymer micelles and the photocontrolled release of Nile red encapsulation. And by encapsulating NaLuF4:Gd/Yb/Tm UCNPs inside copolymer micelles, the response of the photocleavable N–O bond to the 980 nm laser was much weaker than the response to 365 nm light; however, the photocontrolled release of Nile red could still be effectively triggered by the NIR light of the 980 nm laser.

It is possible that the hydrophobic guest within amphiphilic polymer micelles may leak out and be captured by other species before polymer micelles adhere to the desired focus because of the complexity in an actual release procedure, rendering the reduced efficiency of the nanocarrier system. To describe such a scenario, two water-soluble fluorescent amphiphilic random copolymers of PAV and PAA with photo-cross-linkable coumarin and anthracene pendants, respectively, were chosen to investigate the equilibrating immigration and maleimide-anthracene-based Diels–Alder-trapping of hydrophobic octylmaleimide guest from one type of photo-cross-linked polymer micelles of PAV85% to another of PAA66% in aqueous solution using the emission and absorption spectra techniques.

A novel coumarin-centered amphiphilic star-block polymer of C-(PDMAEMA80-b-PS8)3 has been designed to investigate the pH-induced accompanying outward movement of hydrophobic coumarin centers within the polymer micelles upon protonation.

A novel coumarin-centered amphiphilic star-block polymer of C-(PDMAEMA80-b-PS8)3 has been designed to investigate the pH-induced accompanying outward movement of hydrophobic coumarin centers within the polymer micelles upon protonation.