Reactive Block Research Articles

MODIFICATION OF VEGETABLE OILS WITH REACTIVE COMPOUNDS FOR THE PRODUCTION OF PRINTING INKS

The modification of existing paints and varnishes based on alkyd resins, as well as the creation of new film formers using functionalised oligomers to improve the properties of materials in use, has been carried out. The aim of the work is to study vegetable oils used in the production of printing inks and to modify them in order to improve their technological properties. The work carried out allows the use of printing inks based on modified vegetable oils, with the expansion of their scope of application in the production of various printed products. The modification of vegetable oils was carried out by interaction with synthesised urethane-containing reactive block copolymers. Modification of mustard oil allows to change its structure, to increase its molecular weight by oligomerisation of the oil with obtaining of branched structure. Modified vegetable oils provide fast drying alkyd coatings, even in air. The properties of modified oils, the rate of film formation depend on the chemical nature of the block copolymer, its reactivity. The main processes of oil film structuring are due to oxidative and thermal polymerisation of double bonds of fatty acid residues. Optimisation of the vegetable oil modification process has been carried out, a formulation for the production of printing inks has been developed and production tests have been carried out with positive results.

Sulforaphane prevents the reactivation of HIV-1 by suppressing NFκB signaling

Despite more than 20 years of combination antiretroviral therapy (cART), complete eradication of HIV remains a daunting task. While cART has been very effective in limiting new cycles of infection and keeping viral load below detectable levels with partial restoration of immune functions, it cannot provide a cure. Evidently, the interruption of cART leads to a quick rebound of the viral load within a few weeks. These consistent observations have revealed HIV ability to persist as an undetectable latent reservoir in a variety of tissues that remain insensitive to antiretroviral therapies. The ‘Block-and-Lock’ approach to drive latent cells into deep latency has emerged as a viable strategy to achieve a functional cure. It entails the development of latency-promoting agents with anti-HIV functions. Recent reports have suggested sulforaphane (SFN), an inducer of NRF-2 (nuclear erythroid 2-related factor 2)-mediated antioxidative signaling, to possess anti-HIV properties by restricting HIV replication at the early stages. However, the effect of SFN on the expression of integrated provirus remains unexplored. We have hypothesized that SFN may promote latency and prevent reactivation. Our results indicate that SFN can render latently infected monocytes and CD4+ T cells resistant to reactivation. SFN treatments antagonized the effects of known latency reactivating agents, tumor necrosis pactor (TNF-α), and phorbol 12-myristate 13-acetate (PMA), and caused a significant reduction in HIV transcription, viral RNA copies, and p24 levels. Furthermore, this block of reactivation was found to be mediated by SFN-induced NRF-2 signaling that specifically decreased the activation of NFκB signaling and thus restricted the HIV-1 promoter (5′LTR) activity. Overall, our study provides compelling evidence to highlight the latency-promoting potential of SFN which could be used in the ‘Block-and-Lock’ approach to achieve an HIV cure.

Dispersant and Protective Roles of Amphiphilic Poly(ethylene phosphate) Block Copolymers in Polyester/Bone Mineral Composites.

Composites of synthetic bone mineral substitutes (BMS) and biodegradable polyesters are of particular interest for bone surgery and orthopedics. Manufacturing of composite scaffolds commonly uses mixing of the BMS with polymer melts. Melt processing requires a high homogeneity of the mixing, and is complicated by BMS-promoted thermal degradation of polymers. In our work, poly(L-lactide) (PLLA) and poly(ε-caprolactone) (PCL) composites reinforced by commercial β-tricalcium phosphate (βTCP) or synthesized carbonated hydroxyapatite with hexagonal and plate-like crystallite shapes (hCAp and pCAp, respectively) were fabricated using injection molding. pCAp-based composites showed advanced mechanical and thermal characteristics, and the best set of mechanical characteristics was observed for the PLLA-based composite containing 25 wt% of pCAp. To achieve compatibility of polyesters and pCAp, reactive block copolymers of PLLA or PCL with poly(tert-butyl ethylene phosphate) (C1 and C2, respectively) were introduced to the composite. The formation of a polyester-b-poly(ethylene phosphoric acid) (PEPA) compatibilizer during composite preparation, followed by chemical binding of PEPA with pCAp, have been proved experimentally. The presence of 5 wt% of the compatibilizer provided deeper homogenization of the composite, resulting in a marked increase in strength and moduli as well as a more pronounced nucleation effect during isothermal crystallization. The use of C1 increased the thermal stability of the PLLA-based composite, containing 25 wt% of pCAp. In view of positive impacts of polyester-b-PEPA on composite homogeneity, mechanical characteristics, and thermal stability, polyester-b-PEPA will find application in the further development of composite materials for bone surgery and orthopedics.

Optimal timing of oral metyrapone intake for the suppression of cold-pressor stress-induced cortisol release

BackgroundPharmacological manipulation of cortisol levels is instrumental in elucidating mechanisms underlying acute stress effects and for distinguishing the physiological and behavioral effects of cortisol from those of the adrenergic system. Administration (oral or IV) of hydrocortisone is a direct and efficient method to elevate cortisol, and thus, frequently used in psychobiological stress research. However, lowering of cortisol (i.e. blockade of stress cortisol) requires a more sophisticated approach, such as the administration of the corticostatic compound metyrapone (MET). However, there is insufficient knowledge about the temporal dynamics of MET for the blocking of stress-induced cortisol reactivity. Thus, the present study aimed to build up an experimental protocol suitable to suppress acute behavioral stress-induced cortisol secretion by MET. Methods50 healthy young men were randomly assigned to one of five treatment groups. They received 750 mg oral MET either 30 (n = 9), 45 (n = 11), or 60 (n = 10) minutes before exposure to a combined cold pressor and mental arithmetic test (stress induction), or were subjected to two different control treatments (placebo 60 min before stress (n = 10) or MET 30 min before non-stressful warm-water condition (n = 10)). Salivary cortisol concentration, hemodynamics, and subjective ratings were assessed. ResultsSuppression of cold stress-induced cortisol release was strongest when MET intake was scheduled 30 min prior to stress onset. Cardiovascular stress-responses and subjective ratings remained unaffected by MET. ConclusionIn healthy young males, 750 mg of MET efficiently block cold stress-induced cortisol release when oral administration is scheduled 30 min prior to stress onset. This finding may guide future research in improving timing of suppression of stress-induced cortisol secretion.

Hydroxyl-functionalized block co-polyimide enables simultaneously improved toughness and strength of tetrafunctional epoxy resin

Tetrafunctional epoxy resins are widely used as matrix of advanced composite materials due to their excellent high temperature performance. However, the highly crosslinking density of tetrafunctional epoxy resins results in an inherent brittleness, which limits its further application. In this work, hydroxyl-functionalized block co-polyimide (BPADA-ODA/HAB) is first synthesized by the condensation of 3,3′-Dihydroxybenzidine and 4,4′-Diaminodiphenyl ether with 4,4'-(4,4′-isopropylidenediphenoxy) di-phthalic anhydride, and used to toughen tetrafunctional epoxy resins. The co-polyimide molecules provide reactive blocks that participate in the curing reaction of epoxy resin and decrease the crosslinking density of epoxy resin; the co-polyimide can form nano-sized separated phase via self-assembly, which could activate additional energy dissipative mechanisms to enhance the resistance of failure for the epoxy resins. With 5% BPADA-ODA/HAB, the resultant epoxy resins exhibit simultaneous enhancements in impact strength and tensile strength, 184% and 150% higher than those of neat epoxy resin. This study provides an efficient method for preparing tough and strong tetrafunctional epoxy resins, which are expected to be applied more broadly in industries.

Synthesis of poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate)reactive block copolymer with controlled reactivity for toughening multifunctional epoxy resin

AbstractMultifunctional epoxy resins are inherently brittle due to the extremely high cross‐linking density, thus the enhancement in the toughness is rather important for the industrial application. In this work, a reactive poly(hydroxyethyl methacrylate)‐b‐poly(propylene glycol)‐b‐poly(hydroxyethyl methacrylate) (PHEMA‐PPG‐PHEMA) is synthesized by using an atom transfer radical polymerization to toughen trifunctional diglycidyl 4,5‐epoxy cyclohexane‐1,2‐dicarboxylate (TDE‐85). A controllable system is constructed, in which the reaction temperature of TDE‐85 with the hydroxyl of PHEMA‐PPG‐PHEMA is lower than with the curing agent. As a result, both heterogeneous and homogeneous structures can be formed in composites through controlling reaction temperature. It is found that the toughness of composites with the heterogeneous structure is effectively improved without sacrificing the tensile strength, tensile modulus, and glass transition temperature. Specifically, the mode‐1 critical stress intensity factor and critical strain energy release rate of TDE‐85/10 wt% PHEMA‐PPG‐PHEMA are increased to 0.77 MPam1/2 and 146 J/m2, respectively, which are effectively enhanced by 32.8% and 70.3%. This can be ascribed to combined toughening effects from the cavitation of the PHEMA‐PPG‐PHEMA phase, the matrix shear yielding, and the enhanced interface bonding strength due to the reaction between TDE‐85 and PHEMA‐PPG‐PHEMA. Thus, this study paves a novel strategy to improve the toughness of epoxy resin by controlling the curing reaction.

Polymer-Tethered Nanoparticles: From Surface Engineering to Directional Self-Assembly.

Current interest in nanoparticle ensembles is motivated by their collective synergetic properties that are distinct from or better than those of individual nanoparticles and their bulk counterparts. These new advanced optical, electronic, magnetic, and catalytic properties can find applications in advanced nanomaterials and functional devices, if control is achieved over nanoparticle organization. Self-assembly offers a cost-efficient approach to produce ensembles of nanoparticles with well-defined and predictable structures. Nanoparticles functionalized with polymer molecules are promising building blocks for self-assembled nanostructures, due to the comparable dimensions of macromolecules and nanoparticles, the ability to synthesize polymers with various compositions, degrees of polymerization, and structures, and the ability of polymers to self-assemble in their own right. Moreover, polymer ligands can endow additional functionalities to nanoparticle assemblies, thus broadening the range of their applications.In this Account, we describe recent progress of our research groups in the development of new strategies for the self-assembly of nanoparticles tethered to macromolecules. At the beginning of our journey, we developed a new approach to patchy nanoparticles and their self-assembly. In a thermodynamically driven strategy, we used poor solvency conditions to induce homopolymer surface segregation in pinned micelles (patches). Patchy nanoparticles underwent self-assembly in a well-defined and controlled manner. Following this work, we overcame the limitation of low yield of the generation of patchy nanoparticles, by using block copolymer ligands. For block copolymer-capped nanoparticles, patch formation and self-assembly were "staged" by using distinct stimuli for each process. We expanded this work to the generation of patchy nanoparticles via dynamic exchange of block copolymer molecules between the nanoparticle surface and micelles in the solution. The scope of our work was further extended to a series of strategies that utilized the change in the configuration of block copolymer ligands during nanoparticle interactions. To this end, we explored the amphiphilicity of block copolymer-tethered nanoparticles and complementary interactions between reactive block copolymer ligands. Both approaches enabled exquisite control over directional and self-limiting self-assembly of complex hierarchical nanostructures. Next, we focused on the self-assembly of chiral nanostructures. To enable this goal, we attached chiral molecules to the surface of nanoparticles and organized these hybrid building blocks in ensembles with excellent chiroptical properties. In summary, our work enables surface engineering of polymer-capped nanoparticles and their controllable and predictable self-assembly. Future research in the field of nanoparticle self-assembly will include the development of effective characterization techniques, the synthesis of new functional polymers, and the development of environmentally responsive self-assembly of polymer-capped nanoparticles for the fabrication of nanomaterials with tailored functionalities.

Self-healable triboelectric nanogenerators based on ionic poly(hindered urea) network materials cross-linked with fluorinated block copolymers

The versatility of a reactive block copolymer approach to fabricate ionic poly(hindered urea)-based covalent adaptive networks having pendant fluorinated species formulated with ionic liquid for effective self-healable triboelectric nanogenerators.

Recorded Mental Health Recovery Narratives as a Resource for People Affected by Mental Health Problems: Development of the Narrative Experiences Online (NEON) Intervention.

BackgroundThe internet enables sharing of narratives about health concerns on a substantial scale, and some digital health narratives have been integrated into digital health interventions. Narratives describing recovery from health problems are a focus of research, including those presented in recorded (eg, invariant) form. No clinical trial has been conducted on a web-based intervention providing access to a collection of Recorded Recovery Narratives (RRNs).ObjectiveThis study presents knowledge produced through the development of the Narrative Experiences Online (NEON) Intervention, a web-based intervention incorporating the algorithmic recommendation of RRNs.MethodsKnowledge was gathered through knowledge integration (KI) activities. KI1 synthesized previous studies to produce the NEON Impact Model describing how accessing RRNs produces health-related outcomes. KI2 developed curation principles for the NEON Collection of RRNs through consultation with the NEON Lived Experience Advisory Panel and the curation of a preliminary collection. KI3 identified harm minimization strategies for the NEON Intervention through consultation with the NEON International Advisory Board and Lived Experience Advisory Panel. The NEON Intervention was finalized through 2 research studies (RS). In RS1, mental health service users (N=40) rated the immediate impact of randomly presented narratives to validate narrative feedback questions used to inform the recommendation algorithm. In RS2, mental health service users (n=25) were interviewed about their immediate response to a prototype of the NEON Intervention and trial procedures and then were interviewed again after 1 month of use. The usability and acceptability of the prototype and trial procedures were evaluated and refinements were made.ResultsKI1 produced the NEON Impact Model, which identifies moderators (recipient and context), mechanisms of connection (reflection, comparison, learning, and empathy), processes (identification of change from narrative structure or content and internalization of observed change), and outcomes (helpful and unhelpful). KI2 identified 22 curation principles, including a mission to build a large, heterogeneous collection to maximize opportunities for connection. KI3 identified seven harm minimization strategies, including content warnings, proactive and reactive blocking of narratives, and providing resources for the self-management of emotional distress. RS1 found variation in the impact of narratives on different participants, indicating that participant-level feedback on individual narratives is needed to inform a recommender system. The order of presentation did not predict narrative feedback. RS2 identified amendments to web-based trial procedures and the NEON Intervention. Participants accessed some narratives multiple times, use reduced over the 4-week period, and narrative feedback was provided for 31.8% (105/330) of narrative accesses.ConclusionsRRNs can be integrated into web-based interventions. Evaluating the NEON Intervention in a clinical trial is feasible. The mixed methods design for developing the NEON Intervention can guide its extension to other clinical populations, the design of other web-based mental health interventions, and the development of narrative-based interventions in mental health.

Subject-independent decoding of affective states using functional near-infrared spectroscopy.

Affective decoding is the inference of human emotional states using brain signal measurements. This approach is crucial to develop new therapeutic approaches for psychiatric rehabilitation, such as affective neurofeedback protocols. To reduce the training duration and optimize the clinical outputs, an ideal clinical neurofeedback could be trained using data from an independent group of volunteers before being used by new patients. Here, we investigated if this subject-independent design of affective decoding can be achieved using functional near-infrared spectroscopy (fNIRS) signals from frontal and occipital areas. For this purpose, a linear discriminant analysis classifier was first trained in a dataset (49 participants, 24.65±3.23 years) and then tested in a completely independent one (20 participants, 24.00±3.92 years). Significant balanced accuracies between classes were found for positive vs. negative (64.50 ± 12.03%, p<0.01) and negative vs. neutral (68.25 ± 12.97%, p<0.01) affective states discrimination during a reactive block consisting in viewing affective-loaded images. For an active block, in which volunteers were instructed to recollect personal affective experiences, significant accuracy was found for positive vs. neutral affect classification (71.25 ± 18.02%, p<0.01). In this last case, only three fNIRS channels were enough to discriminate between neutral and positive affective states. Although more research is needed, for example focusing on better combinations of features and classifiers, our results highlight fNIRS as a possible technique for subject-independent affective decoding, reaching significant classification accuracies of emotional states using only a few but biologically relevant features.

Selenonium Polyelectrolyte Synthesis through Post-Polymerization Modifications of Poly (Glycidyl Methacrylate) Scaffolds.

Atom transfer radical polymerization of glycidyl methacrylate monomer with poly(ethylene glycol)-based macroinitiators leads to the formation of reactive block copolymers. The epoxide side-chains of these polymers can be subjected to a regiospecific base-catalyzed nucleophilic ring-opening reaction with benzeneselenol under ambient conditions. The ß-hydroxy selenide linkages thus formed can be alkylated to access polyselenonium salts. 77Se-NMR indicates the formation of diastereomers upon alkylation. In such a manner, sequential post-polymerization modifications of poly(glycidyl methacrylate) scaffolds via selenium-epoxy and selenoether alkylation reactions furnish practical access to poly(ethylene glycol)-based cationic organoselenium copolymers.

Tailoring Azlactone-Based Block Copolymers for Stimuli-Responsive Disassembly of Nanocarriers.

Stimuli-responsive nanoparticles based on a reactive block copolymers (BCPs) of poly(ethylene glycol)-b-poly(2-vinyl-4,4-dimethylazlactone) (PEG-b-PVDMA) have been fabricated for loading and controlled release of molecular cargoes. Microphase segregation of PEG-b-PVDMA BCPs enables the construction of well-defined nanoparticles in aqueous solutions. The azlactone groups in VDMA repeat units offer active sites for hydrophilization of the BCPs and functionalization by primary amines. The hydrophilization of PEG-b-PVDMA BCPs induces gradual reconstruction and dissociation of the BCP nanoparticles. Functional primary amines can be conjugated to PEG-b-PVDMA BCPs, yielding azobenzene- and pyridine-containing BCPs. The self-assembled nanoparticles made from the functionalized BCPs can disassemble in response to different external stimuli (e.g., addition of β-cyclodextrin and pH changes). The gradual reconstruction of functionalized PEG-b-PVDMA BCP nanoparticles caused by hydrolysis of residual azlactone groups provides a novel method to engineer sub-50 nm, well-dispersed, stimuli-responsive nanoparticles. These nanoparticles can incorporate molecular cargoes and release them upon external stimuli, making the azlactone-containing BCPs attractive platforms for the development of controlled delivery vehicles.

Abstract B100: AO-176, a highly differentiated humanized anti-CD47 antibody, exhibits single-agent and combination antitumor efficacy with chemotherapy and targeted antibodies

Abstract Purpose of study: To determine whether AO-176, a highly differentiated, humanized antibody targeting CD47, shows efficacy alone or in combination with a variety of approved anti-cancer drugs in solid tumors. Methods: We investigated AO-176 as a single agent and in combination with chemotherapies and targeted antibodies, utilizing standard in vitro phagocytosis assays, tumor cell killing assays, and in vivo xenograft models. Results: AO-176 is a highly-differentiated anti-CD47 antibody that not only blocks the CD47/SIRPα interaction to stimulate phagocytosis of tumor cells, but also exerts direct killing activity on tumor cells (non-ADCC), induces immunogenic cell death, and exhibits preferential binding to tumor cells compared to normal cells. In addition, tumor-specific CD47 binding by AO-176 increases in the acidic tumor microenvironment. As a single agent, AO-176 induced cell killing (14-52% Annexin V positivity, EC50 = 1-30 μg/ml) and phagocytosis (10-34%, EC50 = 0.8-3.3 μg/ml) in ovarian, gastric, non-small cell lung, head and neck, colorectal, thyroid, pancreatic and endometrial solid tumor cell lines. When combined with tumor-targeted antibodies (i.e. cetuximab against head and neck and colorectal cancer cell lines, or the checkpoint inhibitor avelumab against ovarian cancer cell lines), AO-176 significantly enhanced phagocytosis of the tumor cells in vitro. In combination with the chemotherapeutics paclitaxel and cisplatin, AO-176 also potentiated direct tumor killing of gastric cancer cells in vitro. In vivo, AO-176 showed potent single-agent anti-tumor activity against ovarian and gastric tumor xenografts. These data add to the previous pre-clinical anti-tumor activity of AO-176 reported in breast cancer, multiple myeloma, and non-Hodgkin’s lymphoma xenografts. When cisplatin or paclitaxel was added to the AO-176 treatment regimen against xenografted ovarian tumors in vivo, significant combination anti-tumor activity was observed. We then sought to extend our promising in-vitro findings from combining AO-176 with a checkpoint inhibitor to in-vivo models. As AO-176 is human CD47-specific, we utilized an in-house murine reactive anti-CD47 blocking antibody and combined it with a murine-reactive anti-PDL1 antibody to treat MC38 murine tumors established in syngeneic mice. Combination of the two antibodies significantly improved anti-tumor efficacy compared to either single agent. Conclusions: AO-176 has demonstrated broad in vitro phagocytosis/killing as well as in vivo efficacy that supports its development, both as a single agent and in combination with other anti-cancer drugs. With a highly differentiated mechanism of action and binding profile, AO-176 may have the potential to improve upon the safety and efficacy profiles relative to other agents in this class. AO-176 is currently being evaluated in a Phase 1 clinical trial (NCT03834948) for the treatment of patients with select solid tumors. Citation Format: Casey Wilson, Myriam Bouchlaka, Robyn Puro, Ben Capoccia, Ronald Hiebsch, Prabir Chakraborty, Michael Donio, Vicki Sung, Daniel Pereira. AO-176, a highly differentiated humanized anti-CD47 antibody, exhibits single-agent and combination antitumor efficacy with chemotherapy and targeted antibodies [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr B100. doi:10.1158/1535-7163.TARG-19-B100

Alternating Copolymerization of Inorganic Nanoparticles.

Nanoparticle self-assembly has emerged as an indispensable tool in designing structured materials with a wide range of applications, but quantitatively predicting the assembly process and structures still remains challenging. Drawing inspiration from the toolbox of molecular reactions and behaviors is of utmost importance in further advancement of principles and theories for assembling nanoparticles at a length scale orders of magnitude larger. Here we represent a general paradigm for the predictive self-assembly of binary inorganic nanoparticles into linear nanostructures in periodic sequence by expanding the horizon of alternating copolymerization at the molecular level to nanoscale colloidal systems. Nanoparticles grafted with reactive block copolymers are viewed as nanoscale monomers ("nanomers"), and the rapid dimerization of co-nanomers into molecular dipole-like dimers, resembling the preferential formation of dimeric intermediates or charge-transfer complexes from co-monomers in molecular copolymerization, is crucial to the organization of co-nanomers in alternating sequence. We also demonstrate that the classic kinetics and statistics of polycondensation of molecular alternating copolymers (e.g., Nylon-66) can be utilized to quantitatively predict the copolymerization process of nanomers.

Microspheres with Tunable Porosity Based on Reactive Block Copolymer: Preparation and Vapor‐Healing Behavior

AbstractHerein, a simple route to prepare porous microspheres with tuned pore structure and potential functionality based on epoxy functionalized block copolymers, poly hydroxypropyl methacrylate‐b‐ poly glycidyl methacrylate (PHPMA‐b‐PGMA), through a water‐in‐oil‐in‐water (W/O/W) double emulsion is reported. The effect of surfactant concentration and the composition of block copolymers are investigated. The solvent vapor swelling behavior of porous microspheres before and after cross‐linking is studied. It is interesting that after the swelling, the cross‐linked open pores are self‐healed to form closed pores, whereas the uncross‐linked ones are collapsed. It is believed that this observation will be useful in guest carrying and control release, and find its application in biomedical and pharmaceuticals.

Robust, highly porous hydrogels templated within emulsions stabilized using a reactive, crosslinking triblock copolymer

PolyHIPEs (PHs) are porous polymers that are typically templated within surfactant-stabilized high internal phase emulsions (HIPEs). Hydrogel PHs (HG-PHs) have exhibited potential as absorbents, adsorbents, release systems, and tissue engineering scaffolds. Recent work has shown that HG-PHs with highly temperature sensitive water uptakes could be produced using a reactive block copolymer (BC) as the sole surfactant, monomer, and crosslinker. It is not clear, however, whether these properties could be transferred to a HG-PH based on conventional hydrogel monomers and synthesized within a HIPE stabilized using a reactive BC. This work investigates HG-PHs based on acrylamide (AAm) synthesized within a HIPE stabilized by F-127-DMA, a reactive crosslinking BC based on methacrylate endcapped Pluronic F-127 (a commercial PEO-PPO-PEO triblock copolymer with poly(ethylene oxide) (PEO) endblocks and a poly(propylene oxide) (PPO) midblock). All the F-127-DMA-containing HG-PHs exhibited highly interconnected porous structures, low densities, and robust compressive behaviors with no chalkiness. The combination of F-127-DMA crosslinking and emulsion templating produced amplified and accelerated water uptakes, up to 161 g/g, associated with hydrogel-swelling-driven void expansion, and enhanced the temperature sensitivity, with the uptake decreasing by ∼50% between 5 and 60 °C, compared to reference HG-PHs and to conventional hydrogels.

Glucose-Responsive Polymeric Micelles via Boronic Acid-Diol Complexation for Insulin Delivery at Neutral pH.

In the present study, glucose-responsive polymeric complex micelles based on the complexation of phenylboronic-acid-based (PBA-based) block copolymer and diol-functionalized polymers are reported. The phenylboronic-acid- and diol-based block copolymers were successfully synthesized in only two reaction steps using reversible addition-fragmentation chain-transfer (RAFT) polymerization and postpolymerization modification of the obtained poly[( N-acryloylmorpholine- block-( N-acryloylmorpholine- co-pentafluorophenyl acrylate)], poly[(AMP- b-(AMP- co-PFPA)], reactive block copolymer. The self-assembly of the complex micelles was investigated under neutral conditions using dynamic light scattering (DLS) and transmission electron microscopy (TEM). The interaction of the PBA block copolymer and diol-containing polymer via boronate ester bond was investigated by 1H NMR and UV-vis spectroscopy. The complex micelles enhanced the glucose responsiveness under physiological conditions compared to simple PBA micelles. Furthermore, the successful glucose-triggered release of FITC-insulin from the polymeric micelles was investigated.

Reactive block copolymers for patterned surface immobilization with sub-30 nm spacing

Reactive polystyrene-block-polyisoprene copolymers are synthesized by nitroxide-mediated polymerization, self-assemble within ultra-thin films, and exhibit surface reactivity for patterned immobilization.

Functionalization-Induced Self-Assembly of Block Copolymers for Nanoparticle Synthesis.

Nanoparticle synthesis was demonstrated via functionalization-induced self-assembly (FISA) of block copolymers using Suzuki-Miyaura cross-coupling. In situ self-assembly was triggered in organic media by the progressive installation of solvophobic pendant groups onto an initially soluble diblock copolymer, rendering the reactive block insoluble and causing the formation of spherical polymeric micelles. Self-assembly was found to depend on the percent functionalization (f%), where after a critical threshold micelles were accessible that increased in size with increasing f% values. We found the chemical nature of the installed functional group to be crucial for conducting FISA and for controlling the solution morphology, with relatively solvophilic adducts remaining as unimers and increasingly solvophobic adducts trending toward larger micelles, from ca. 40 to 100 nm in diameter. The core and corona of the anticipated micellar structure were visualized using fluorine mapping through electron energy loss spectroscopy, in conjunction with FISA achieved through pendent trifluorophenyl functionality. This work establishes FISA as a new, versatile synthetic strategy to create nanoparticles having tunable morphologies with potential application as molecular payload delivery vehicles.

Recycling of poly(ethylene terephthalate) by chain extension during reactive extrusion using functionalized block copolymers synthesized by RAFT polymerization

ABSTRACTIn this study, a series of reactive block copolymers of glycidyl methacrylate (G), styrene (S), and maleic anhydride (MA) (GS–SMA–GS), with well‐defined properties and high number average functionalities, is presented. They were synthesized through reversible addition–fragmentation chain transfer polymerization (RAFT) and evaluated as chain extenders in reactive extrusion recycling of poly(ethylene terephthalate) (rPET). Modification of the process using GS–SMA–GS results in increased melt flow and intrinsic viscosities higher than those of conventional rPET. Results show that increasing epoxide content makes chain organization in rPET difficult and promotes lower crystallization rates and lower degrees of crystallinity, both of which are characteristics suited to produce preforms with the desired clarity. Chain‐extended rPET exhibits improved rheological characteristics with increasing glycidyl methacrylate content. Chain‐extended rPET using GS–SMA–GS shows enhanced complex viscosity; elastic and viscous modules, which are indicative of high melt elasticity, improved mechanical properties, and processability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46771.