Direct Synthesis of Thermally Responsive DMA/NIPAM Diblock and DMA/NIPAM/DMA Triblock Copolymers via Aqueous, Room Temperature RAFT Polymerization

Smart block copolymers of PVP and an alkylated PVP derivative: synthesis, characterization, thermoresponsive behaviour and self-assembly

Stimuli responsive block copolymers of biocompatible poly(3-ethyl-N-vinylpyrrolidone) and poly(N-vinylpyrrolidone), i.e. EPVP–PVP, were readily synthesized via RAFT-mediated polymerization.

One-pot preparation of BAB triblock copolymer nano-objects through bifunctional macromolecular RAFT agent mediated dispersion polymerization

Nano-assemblies of a BAB triblock copolymer containing a solvophilic A block and two solvophobic B blocks were prepared through dispersion RAFT polymerization.

pH responsive highly branched poly(N-isopropylacrylamide) with trihistidine or acid chain ends

Thermally responsive highly branched poly(N-isopropyl acrylamide)s (HB-PNIPAM) were prepared and end-functionalised to give polymers with acid or trihistidine end groups. ​The ionisation of the end groups affects the swelling of desolvated globules.

Cationic and reactive primary amine-stabilised nanoparticles via RAFT aqueous dispersion polymerisation

Synthesis of cationic reactive primary amine-functionalized diblock copolymer nano-objects via polymerisation-induced self-assembly (PISA) using a RAFT aqueous dispersion polymerisation formulation is reported.

Well-defined polyurethane-graft-poly(N,N-dimethylacrylamide) copolymer with a controlled graft density and grafted chain length: synthesis and its application as a Pickering emulsion

Well-defined PU-g-PDMA graft copolymers with controlled graft densities and grafted chain lengths could be facilely synthesized by combining the polyaddition reaction with the RAFT polymerization.

A logic gate for external regulation of photopolymerization

The use of photocatalysts for visible light mediated reversible deactivation radical polymerization (RDRP) provides an efficient route for the synthesis of well-defined polymers with spatial, temporal and sequence control.

Facile production of nanoaggregates with tuneable morphologies from thermoresponsive P(DEGMA-co-HPMA)

RAFT-mediated emulsion polymerization of styrene and subsequent morphological transition produces nanoaggregates with tuneable morphologies.

RAFT polymerization of ciprofloxacin prodrug monomers for the controlled intracellular delivery of antibiotics

Prodrug monomers derived from the antibiotic ciprofloxacin were synthesized with phenolic or aliphatic esters linking the drug to a polymerizable methacrylate group.

Development of Non-Viral, Trophoblast-Specific Gene Delivery for Placental Therapy

Low birth weight is associated with both short term problems and the fetal programming of adult onset diseases, including an increased risk of obesity, diabetes and cardiovascular disease. Placental insufficiency leading to intrauterine growth restriction (IUGR) contributes to the prevalence of diseases with developmental origins. Currently there are no therapies for IUGR or placental insufficiency. To address this and move towards development of an in utero therapy, we employ a nanostructure delivery system complexed with the IGF-1 gene to treat the placenta. IGF-1 is a growth factor critical to achieving appropriate placental and fetal growth. Delivery of genes to a model of human trophoblast and mouse placenta was achieved using a diblock copolymer (pHPMA-b-pDMAEMA) complexed to hIGF-1 plasmid DNA under the control of trophoblast-specific promoters (Cyp19a or PLAC1). Transfection efficiency of pEGFP-C1-containing nanocarriers in BeWo cells and non-trophoblast cells was visually assessed via fluorescence microscopy. In vivo transfection and functionality was assessed by direct placental-injection into a mouse model of IUGR. Complexes formed using pHPMA-b-pDMAEMA and CYP19a-923 or PLAC1-modified plasmids induce trophoblast-selective transgene expression in vitro, and placental injection of PLAC1-hIGF-1 produces measurable RNA expression and alleviates IUGR in our mouse model, consequently representing innovative building blocks towards human placental gene therapies.

Aqueous RAFT Polymerization of Imidazolium-Type Ionic Liquid Monomers: En Route to Poly(ionic liquid)-Based Nanoparticles through RAFT Polymerization-Induced Self-Assembly

The synthesis by aqueous RAFT polymerization of hydrophilic narrowly dispersed imidazolium-based poly(ionic liquid)s (Đ typically below 1.20) is reported. Full monomer conversion is achieved within hours and high end-group fidelity of the living end groups affords the preparation of well-defined block copolymers. The resulting poly(ionic liquid) macroRAFT agents are finally exploited to polymerize 2-vinylpyridine in water and generate PIL-based nanoparticles of various morphologies (spheres, vesicles, or worms) in a one-pot surfactant-free process.

Thermosensitive tribrachia star-shaped s-P(NIPAM-co-DMAM) random copolymer micelle aggregates: Preparation, characterization, and drug release applications

Tribrachia star-shaped random copolymers with tunable thermosensitive phase transition temperature were designed and synthesized via a simple one-pot ammonolysis reaction approach with trimesic acid as cores. The self-assembly micellization behavior of the copolymers in aqueous solution was examined by surface tension, UV-vis transmittance, transmission electron microscope, and dynamic light scattering measurements, etc. The results indicated that the resultant copolymers formed thermosensitive micelle aggregates through hydrophobic interactions among the isopropyl groups of poly(N-isopropylacrylamide) PNIPAM chains and inter-star association at a polymer concentration above critical aggregation concentrations from 4.06 to 6.55 mg L(-1), with a cloud point range from 36.6℃ to 52.1℃, and homogeneously distributed micelle size below 200 nm. The arm length and the compositional ratios of the two comonomers had effect on physicochemical properties of the polymer micelle aggregates. Particularly, the cloud point values were enhanced as the (N,N-dimethylacrylamide) DMAM monomer was introduced and reached to 36.6℃ and 41.0℃-44.7℃ when the mass ratio of NIPAM to DMAM was 90:10 and 80:20, respectively. The thermo-triggered drug release and cytotoxicity were evaluated to confirm the applicability of the random copolymer micelle aggregates as novel drug targeted release carriers.

Well-defined single polymer nanoparticles for the antibody-targeted delivery of chemotherapeutic agents

Aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization was employed to prepare a series of linear copolymers of N,N-dimethylacrylamide (DMA) and 2-hydroxyethylacrylamide (HEAm) with narrow Đ values over a molecular weight range spanning three orders of magnitude (103 to 106 Da). Trithiocarbonate-based RAFT chain transfer agents (CTAs) were grafted onto these scaffolds using carbodiimide chemistry catalyzed with DMAP. The resultant graft chain transfer agent (gCTA) was subsequently employed to synthesize polymeric brushes with a number of important vinyl monomer classes including acrylamido, methacrylamido, and methacrylate. Brush polymerization kinetics were evaluated for the aqueous RAFT polymerization of DMA from a 10 arm gCTA. Polymeric brushes containing hydroxyl functionality were further functionalized in order to prepare 2nd generation gCTAs which were subsequently employed to prepare polymers with a brushed-brush architecture with molecular weights in excess of 106 Da. These resultant single particle nanoparticles (SNPs) were employed as drug delivery vehicles for the anthracycline-based drug doxorubicin via copolymerization of DMA with a protected carbazate monomer (bocSMA). Cell-specific targeting functionality was also introduced via copolymerization with a biotin-functional monomer (bioHEMA). Drug release of the hydrazone linked doxorubicin was evaluated as function of pH and serum and chemotherapeutic activity was evaluated in SKOV3 ovarian cancer cells.

Preparation of complex multiblock copolymers via aqueous RAFT polymerization at room temperature

Room temperature RAFT polymerisation for the design of multiblock acrylate/acrylamide copolymers.

Poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) diblock copolymers: synthesis, self-assembly and interaction

Evaluation of the Flory-Huggins interaction parameter confirmed the self-assembly of a series of RAFT-synthesized poly(4-vinylpyridine)-block-poly(N-acryloylpiperidine) diblock copolymers.

Constructing nanosized CdTe nanocrystal clusters with thermo-responsive photoluminescence characteristics

Photoluminescence clusters of CdTe nanocrystals self-assembled by PNAEAM-b-PNIPAM copolymers represent sensitive and reversible thermo-responsive properties in aqueous solutions.

Synthesis of well-defined α,ω-telechelic multiblock copolymers in aqueous medium: in situ generation of α,ω-diols

The synthesis of well-defined α,ω-dihydroxyl telechelic multiblock copolymers by sequential in situ chain extensions via aqueous Cu(0) mediated living radical polymerization (SET-LRP) is reported.

Disclosing the nature of thermo-responsiveness of poly(N-isopropyl acrylamide)-based polymeric micelles: aggregation or fusion?

We disclose a fusion-dominated thermo-responsive behaviour of a poly(N-isopropyl acrylamide)-based copolymer micelle by TEM after in situ photo-cross-linking morphologies.

A novel and controllable route for preparing high solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions

High solid-content and low-viscosity poly(acrylamide-co-acrylic acid) aqueous latex dispersions were obtained through a novel strategy, which involves swelling followed by diffusion and redox initialized polymerization inside the seed particle.

Preparation of cylindrical multi-compartment micelles by the hierarchical self-assembly of ABC triblock polymer in solution

Amphiphilic linear ABC triblock copolymer PnBA₂₈-b-PS₃₇-b-P2VP₇₃ was prepared by the RAFT method. Spherical patchy micelles and cylindrical MCMs were formed in different steps of its two-step hierarchical self-assembly in selected solvents.

Surface modification of polydopamine coated particles via glycopolymer brush synthesis for protein binding and FLIM testing

Polymer coatings on silica cores as well as fluorescent protein binding and fluorescent lifetime analysis.

Tunable LCST behavior of poly(N-isopropylacrylamide/ionic liquid) copolymers

Tunable LCST of PNIPAM–IL copolymers.

RAFT polymerization of linear ABC triblock copolymer PtBA-b-PS-b-P2VP and regulation of its hierarchical self-assembly structure in solution

Linear ABC triblock copolymer PtBA

Controlling topological entanglement in engineered protein hydrogels with a variety of thiol coupling chemistries

Topological entanglements between polymer chains are achieved in associating protein hydrogels through the synthesis of high molecular weight proteins via chain extension using a variety of thiol coupling chemistries, including disulfide formation, thiol-maleimide, thiol-bromomaleimide and thiol-ene. Coupling of cysteines via disulfide formation results in the most pronounced entanglement effect in hydrogels, while other chemistries provide versatile means of changing the extent of entanglement, achieving faster chain extension, and providing a facile method of controlling the network hierarchy and incorporating stimuli responsivities. The addition of trifunctional coupling agents causes incomplete crosslinking and introduces branching architecture to the protein molecules. The high-frequency plateau modulus and the entanglement plateau modulus can be tuned by changing the ratio of difunctional chain extender to the trifunctional branching unit. Therefore, these chain extension reactions show promise in delicately controlling the relaxation and mechanical properties of engineered protein hydrogels in ways that complement their design through genetic engineering.

Glucose-containing diblock polycations exhibit molecular weight, charge, and cell-type dependence for pDNA delivery

A series of diblock glycopolycations were created by polymerizing 2-deoxy-2-methacrylamido glucopyranose (MAG) with either a tertiary amine-containing monomer, N-[3-(N,N-dimethylamino) propyl] methacrylamide (DMAPMA), or a primary amine-containing unit, N-(2-aminoethyl) methacrylamide (AEMA). Seven structures were synthesized via aqueous reversible addition-fragmentation chain transfer (RAFT) polymerization that varied in the block lengths of MAG, DMAPMA, and AEMA along with two homopolymer controls of DMAPMA and AEMA that lacked a MAG block. The polymers were all able to complex plasmid DNA into polyplex structures and to prevent colloidal aggregation of polyplexes in physiological salt conditions. In vitro transfection experiments were performed in both HeLa (human cervix adenocarcinoma) cells and HepG2 (human liver hepatocellular carcinoma) cells to examine the role of charge type, block length, and cell type on transfection efficiency and toxicity. The glycopolycation vehicles with primary amine blocks and PAEMA homopolymers revealed much higher transfection efficiency and lower toxicity when compared to analogs created with DMAPMA. Block length was also shown to influence cellular delivery and toxicity; as the block length of DMAPMA increased in the glycopolycation-based polyplexes, toxicity increased while transfection decreased. While the charge block played a major role in delivery, the MAG block length did not affect these cellular parameters. Lastly, cell type played a major role in efficiency. These glycopolymers revealed higher cellular uptake and transfection efficiency in HepG2 cells than in HeLa cells, while homopolycations (PAEMA and PDMAPMA) lacking the MAG blocks exhibited the opposite trend, signifying that the MAG block could aid in hepatocyte transfection.

RAFT polymerization of temperature- and salt-responsive block copolymers as reversible hydrogels

Reversible-addition fragmentation chain transfer (RAFT) polymerization enabled the synthesis of novel, stimuli-responsive, AB and ABA block copolymers. The B block contained oligo(ethylene glycol) methyl ether methacrylate (OEG) and was permanently hydrophilic in the conditions examined. The A block consisted of diethylene glycol methyl ether methacrylate (DEG) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (TMA). The A block displayed both salt- and temperature-response with lower critical solution temperatures (LCSTs) dependent on the molar content of TMA and the presence of salt. Higher TMA content in the AB diblock copolymers increased the critical micelle temperatures (CMT) in HPLC-grade water due to an increased hydrophilicity of the A block. Upon addition of 0.9 wt% NaCl, the CMTs of poly(OEG-b-DEG₉₅TMA₅) decreased from 50 °C to 36 °C due to screening of electrostatic repulsion between the TMA units. ABA triblock copolymers displayed excellent hydrogel properties with salt- and temperature-dependent gel points. TMA incorporation in the A block increased the gel points for all triblock copolymers, and salt-response increased with higher TMA composition in the A block. For example, poly(DEG₉₈TMA₂-b-OEG-b-DEG₉₈TMA₂) formed a hydrogel at 40 °C in HPLC-grade water and 26 °C in 0.9 wt% NaCl aqueous solution. These salt- and temperature-responsive AB diblock and ABA triblock copolymers find applications as drug delivery vehicles, adhesives, and hydrogels.

Functional group-dependent self-assembled nanostructures from thermo-responsive triblock copolymers

The ability to control the formation of nanostructures through self-assembly of amphiphilic block copolymers is of great interest in the field of biology and catalysis. In this work we have studied the self-assembling behavior of a new class of thermo-responsive triblock copolymers containing poly(ethylene glycol), and demonstrated the manner in which the aggregation pattern changed on simple functional group transformation on the copolymers. Two different triblock copolymers, poly(ethylene glycol)-b-poly(N-ispropylacrylamide)-b-poly(t-butyl acrylate) (P1) and poly(ethylene glycol)-b-poly(N-isopropylacrylamide)-b-poly(glycidyl methacrylate) (P2) were synthesized using reversible addition-fragmentation chain transfer (RAFT) technique. It was observed that P1 and P2 displayed different temperature dependent solution properties in water, with P1 forming micelles above the LCST of the PNIPA while P2 showing macroscopic phase separation under similar conditions. Thereafter, the tert-butyl group of P1 was converted to the corresponding acid (P1a) and the epoxy groups of P2 was converted to diols (P2a), thus transforming the hydrophobic blocks to hydrophilic ones. Quite interestingly, such transformations led to significant changes in their self-assembling behavior, as both P1a and P2a were seen to form vesicles beyond the LCST of PNIPA. Changes in the hydrophilic fraction in the block copolymers by subtle changes in the functionality and temperature led to the formation of varied nanostructured assemblies, as evident from dynamic light scattering (DLS), transmisison electron microscopy (TEM), and steady-state fluorescence analysis. Such formation of thermo-responsive vesicles induced by simple structural changes in the copolymers is quite interesting and highly significant in drug delivery applications.

Combining RAFT polymerization and thiol-ene click reaction for core-shell structured polymer@BaTiO3 nanodielectrics with high dielectric constant, low dielectric loss, and high energy storage capability

Nanodielectric materials with high dielectric constant, low dielectric loss, and high energy storage capability are highly desirable in modern electric and electronics industries. It has been proved that the preparation of core-shell structured dielectric polymer nanocomposites via "grafting from" method is an effective approach to these materials. However, by using this approach, the deep understanding of the structure-dielectric property relationship of the core-shell structured nanodielectrics has been limited because of the lack of detailed information (e.g., molecular weight, grafting density) about the macromolecules grafted onto the nanoparticle surfaces. In this work, by the combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene click reaction, two types of core-shell structured polymer@BaTiO3 (polymer@BT) nanocomposites with high dielectric constant and low dielectric loss were successfully prepared via a "grafting to" method. Compared with the "grafting from" method, this "grafting to" method has two merits: the molecular weight of the polymer chains in the shell layer can be easily controlled and the grafting density can be tailored by changing the molecular weight of the grafting polymer. Moreover, a clear insight into the relationship among the dielectric properties and energy storage capability of the core-shell structured polymer@BT nanocomposites, the molecular weight of the polymer chains, and the grafting density of the core-shell structured nanoparticles was achieved. The study provides new insights into the design and preparation of nanodielectric materials with desirable dielectric properties.

In situ synthesis of thermo-responsive ABC triblock terpolymer nano-objects by seeded RAFT polymerization

Synthesis of thermo-responsive ABC triblock terpolymer nano-objects by seeded RAFT polymerization is achieved. At temperature above LCST, the triblock terpolymer nano-objects convert into multicompartment nanoparticles.

Manganese(iii) acetylacetonate initiated RAFT polymerizations: an alternative and versatile RAFT initiator

Manganese(iii) acetylacetonate (Mn(acac)₃) was demonstrated to be a versatile and superior RAFT initiator for different kinds of monomers, RAFT agents and noticeably, for a wide range of temperatures.

Facile synthesis, sequence-tuned thermoresponsive behaviours and reaction-induced reorganization of water-soluble keto-polymers

Water-soluble keto-polymers: facile synthesis in methanol on irradiation with visible light at 25 °C, sequence-tuned thermoresponsive behaviours and reaction-induced reorganization.