Self-condensing Vinyl Polymerization Research Articles

Aqueous RAFT Dispersion Polymerization Mediated by an ω,ω-Macromolecular Chain Transfer Monomer: An Efficient Approach for Amphiphilic Branched Block Copolymers and the Assemblies.

Herein, an ω,ω-macromolecular chain transfer monomer (macro-CTM) containing a RAFT (reversible addition-fragmentation chain transfer) group and a methacryloyl group was synthesized and used to mediate photoinitiated RAFT dispersion polymerization of hydroxypropyl methacrylate (HPMA) in water. The macro-CTM undergoes a self-condensing vinyl polymerization (SCVP) mechanism under RAFT dispersion polymerization conditions, leading to the formation of amphiphilic branched block copolymers and the assemblies. Compared with RAFT solution polymerization, it was found that the SCVP process was promoted under RAFT dispersion polymerization conditions. Morphologies of branched block copolymer assemblies could be controlled by varying the monomer concentration and the [HPMA]/[macro-CTM] ratio. The branched block copolymer vesicles could be used as seeds for seeded RAFT emulsion polymerization, and framboidal vesicles were successfully obtained. Finally, degrees of branching of branched block copolymers could be further controlled by using a binary mixture of the macro-CTM and a linear macro-RAFT agent or a small molecule CTM. We believe that this study not only provides a versatile strategy for the preparation of branched block copolymer assemblies but also offers important insights into polymer synthesis via heterogeneous RAFT polymerization.

Facile synthesis of GSH-triggered degradable hyperbranched polymer coprodrug as unimolecular micelles for precise tumor combination chemotherapy

Combination chemotherapy has attracted more intense attention in tumor treatment, in which the drug-loading mode and drug proportion of the nano drug co-delivery system (NDCDS) play an important role in the anti-tumor efficacy. Here, GSH-triggered degradable hyperbranched polymer coprodrugs were designed via the self-condensing vinyl polymerization (SCVP) of the polymerizable prodrug monomers and poly(ethylene glycol) methacrylate (PEGMA) with a GSH-sensitive inimer. The drug proportion of the polymer coprodrugs could be easily adjusted by altering the feeding ratio for a better synergistic effect. The proposed polymer coprodrugs could form unimolecular micelles and be degraded completely to release the two parent drugs (DOX and CPT) responding to the high-level GSH in the tumor cells with a very low drug premature leakage in the intercellular environment and a low mis-release in the normal cells. The optimized one, HBPP-DOX/CPT-5, possessed a low CI50 of 0.11, showing promising potential in safe and effective tumor combination chemotherapy.

Orthogonal synthesis and modification of hyperbranched polymers via different colors of light

AbstractA versatile and straightforward approach for the synthesis of functional hyperbranched polymers with tunable properties is represented utilizing a chromatic orthogonal protocol. The method involves the combination of photo‐induced electron/energy transfer‐reversible addition‐fragmentation chain transfer (PET‐RAFT) and self‐condensing vinyl polymerization (SCVP) under visible light irradiation leading to the formation of hyperbranched polymers with well‐defined properties possessing photo‐caged diene moieties. Upon UV light irradiation, the remaining photoenol functionality was efficiently activated for the post‐functionalization of the synthesized hyperbranched polymers with maleimide functional molecules via Diels‐Alder photo‐click chemistry. Both low molar mass and polymeric maleimide functional click components, namely N‐phenylmaleimide, poly(ethylene glycol)‐maleimide and polycaprolactone‐maleimide were quantitively attached onto the hyperbranched polymers under ambient conditions. The results obtained from our protocol indicate high efficiency and convenience, offering a straightforward strategy for the design and synthesis of functionalized hyperbranched polymers. The chromatic orthogonal nature of the protocol enables precise control over the modification process, adding versatility to the materials obtained. Overall, this research lays the groundwork for novel pathways in material design, opening new possibilities for advanced materials with tailored properties.

Average properties of the self-condensing vinyl polymerization system of comonomers with any initial size distribution

Average properties of the self-condensing vinyl polymerization system of comonomers with any initial size distribution

Facile synthesis of GSH-triggered skeleton-cleavable hyperbranched polymer prodrug as unimolecular micelles for tumor-specific camptothecin delivery

Prodrug unimolecular micelles based on dendrimers or hyperbranched polymers have attracted intense interest in tumor chemotherapy. The preparation of the former one is usually cumbersome, while the stable skeleton in the latter one restricts the drug release. Here, GSH-triggered skeleton-cleavable hyperbranched polymer prodrug was designed via a “Bottom-up” construction strategy, by the self-condensing vinyl polymerization (SCVP) of GSH-sensitive prodrug monomer MA-SS-CPT and PEGMA with a GSH-sensitive inimer MA-SS-Br. It could self-assemble into stable unimolecular micelles, possessing GSH-triggered drug release and disintegration of the hyperbranched skeleton. So, they showed an excellent tumor-specific CPT release in the in vitro drug release and consequently tumor-specific cytotoxicity with an enhanced tumor cell growth inhibition than the free CPT.

One-pot synthesis of hyperbranched polymers via visible light regulated switchable catalysis

Switchable catalysis promises exceptional efficiency in synthesizing polymers with ever-increasing structural complexity. However, current achievements in such attempts are limited to constructing linear block copolymers. Here we report a visible light regulated switchable catalytic system capable of synthesizing hyperbranched polymers in a one-pot/two-stage procedure with commercial glycidyl acrylate (GA) as a heterofunctional monomer. Using (salen)CoIIICl (1) as the catalyst, the ring-opening reaction under a carbon monoxide atmosphere occurs with high regioselectivity (>99% at the methylene position), providing an alkoxycarbonyl cobalt acrylate intermediate (2a) during the first stage. Upon exposure to light, the reaction enters the second stage, wherein 2a serves as a polymerizable initiator for organometallic-mediated radical self-condensing vinyl polymerization (OMR-SCVP). Given the organocobalt chain-end functionality of the resulting hyperbranched poly(glycidyl acrylate) (hb-PGA), a further chain extension process gives access to a core-shell copolymer with brush-on-hyperbranched arm architecture. Notably, the post-modification with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) affords a metal-free hb-PGA that simultaneously improves the toughness and glass transition temperature of epoxy thermosets, while maintaining their storage modulus.

Fabrication of pH and thermal dual-responsive hyperbranched copolymer grafted magnetic graphene oxide via surface-initiated RAFT-SCVP for controlled release of DOX

Herein, a novel stimuli-responsive magnetic graphene oxide/hyperbranched copolymer nanocomposites (GO@Fe3O4 @HBC) was prepared via mixing surface-initiated RAFT and self-condensing vinyl polymerization technique. In the first step, chain transfer monomer (CTM) was synthesized by the esterification reaction between 2-(dodecylthiocarbonothioylthio)− 2-methylpropionic acid (DDMAT) and 2-Hydroxyethyl methacrylate (HEMA). Besides, graphene oxide nanosheets were decorated with Fe3O4 nanoparticles. The surface of magnetic graphene oxide nanosheets was modified with 3-amino propyl (trimethoxysilyl) (APTS) and then the DDMAT was anchored to the surface of their nanosheets via amidification reaction. At last, smart hyperbranched poly (NIPAM-co-AA) was effectively grafted to the surface of magnetic graphene oxide using the SI-RAFT-SCVP technique. The chemical and physical structure of the synthesized GO@Fe3O4 @HBC were investigated by FT-IR, H NMR, GPC, TGA, DLS, CHN, VSM, UV-Vis, SEM, EDAX, and TEM. The synthesized GO@Fe3O4 @HBC was used as a nanocarrier. The drug delivery efficacy of this nanocarrier was investigated in terms of in vitro doxorubicin (DOX) release and MTT assay against HeLa cells, which confirms both acidic pH and thermo-sensitive behavior. The MTT assay also revealed that the nanocarrier without DOX was biocompatible having cell viability greater than 90% for HeLa cells. DOX-loaded nanocarrier showed high cytotoxic effect on HeLa Cells.

GSH-triggered disintegrable hyperbranched polymer prodrug as unimolecular micelles for tumor-specific chemotherapy

A GSH-triggered disintegrable hyperbranched polymer prodrug was designed for tumor-specific chemotherapy, to solve the conflict between the stability and drug release of its unimolecular micelles.

Facile Synthesis of a Redox-Responsive Hyperbranched Polymer Prodrug as a Unimolecular Micelle for the Tumor-Selective Drug Delivery.

Demicellization of the self-assembled multimolecular micelles upon dilution restricts their application as drug delivery systems (DDSs) for tumor treatment. Here, a redox-responsive hyperbranched polymer prodrug (HBPP) was designed with a high drug content of 62.0% as a unimolecular micelle for the tumor-selective drug delivery, via the facile self-condensing vinyl polymerization (SCVP) of redox-responsive doxorubicin-based prodrug monomer MA-SS-DOX and poly(ethylene glycol) methacrylate (PEGMA) with p-chloromethylstyrene (CMS) as an inimer. The unimolecular micelle could be easily obtained with a hydrodynamic diameter of 122 nm, showing excellent GSH-triggered drug release performance with a cumulative release of 60.9% within 85 h but a low premature drug leakage of 3.2%. The unimolecular micelle exhibited selective tumor growth inhibition on HepG2 cells but no obvious cytotoxicity on L02 cells.

Facile synthesis of a hyperbranched polymer prodrug as unimolecular micelles for overcoming multidrug resistance

Hyperbranched polymer prodrug (HBPP) with high drug content was designed as unimolecular micelles for enhanced intracellular drug delivery via one-pot self-condensing vinyl polymerization (SCVP).

Synthesis and Properties of Multi-stimuli-Responsive Water-Soluble Hyperbranched Polymers Prepared Via Reversible Addition–Fragmentation Chain Transfer Self-Condensing Vinyl Polymerization

Synthesis and Properties of Multi-stimuli-Responsive Water-Soluble Hyperbranched Polymers Prepared Via Reversible Addition–Fragmentation Chain Transfer Self-Condensing Vinyl Polymerization

Synthesis of Hyperbranched Polymers via PET‐RAFT Self‐Condensing Vinyl Polymerization in a Flow Reactor

AbstractPhotoinduced polymerization techniques have been used in preparing various polymeric materials as they share several advantages with thermally‐triggered processes using mild conditions, low catalyst concentrations, and easy‐to‐perform experimental conditions. By combining photoinduced eletrotransfer reversible addition–fragmentation chain transfer (RAFT) polymerization with self‐condensing vinyl polymerization (SCVP), in this work, a series of hyperbranched polymers is prepared in a flow reactor. Considered to be an alternative powerful method in improving scalability, reliability, and efficiency, the use of a flow reactor allowed us to synthesize hyperbranched poly(poly(ethylene glycol methyl ether)acrylate) (PPEGMEA) under extremely mild conditions–room temperature, open vessel, and use of LED light and water/methanol mixed solutions. The method also demonstrates considerable controllability in molecular weight and branching density by adjusting the feeding ratio of monomer to transmer, leading to the synthesis of block copolymers.

A Unified Theoretical Treatment on Statistical Properties of the Semi-batch Self-condensing Vinyl Polymerization System

We present a novel generating function (GF) method for the self-condensing vinyl polymerization (SCVP) system with any initial distribution of preexisted polymers. Such a method was proven to be especially useful to investigate the semi-batch SCVP system allowing a sequence of feeding operations during the polymerization. Consequently, the number-, weight-, and z-average molecular weights as well as dispersity index of hyperbranched polymers can be explicitly given, which are determined by predetermined feeding details and conversions in each polymerization step. These analytical results are further confirmed by the corresponding Monte Carlo simulations. Therefore, the present GF method has provided a unified treatment to the semi-batch SCVP system. Accordingly, hyperbranched polymers with desired properties can be prepared by designing feeding details and presetting conversions at each step based on the present GF method.

A Simple Photochemical Route to Hyperbranched Polymers by Using Photolatent Inimer

AbstractA novel and straightforward approach for the synthesis of hyperbranched polymers (HBPs) by photoinduced self‐condensing vinyl polymerization (SCVP) is explored. The SCVP is achieved using a divinyl monomer possessing photocleavable moiety in the inner structure, acting as both photoinitiator and inimer (photolatent inimer) in conjunction with methyl methacrylate (MMA) under UV irradiation. HBPs with different branching densities are successfully produced. Depending on the concentration of inimer and irradiation time, lightly branched, hyperbranched and cross‐linked polymers are formed. The described approach may lead to future directions of photopolymerization in various applications especially in bio related systems requiring highly branched structures without contamination of low‐molar mass photoinitiator fragments.

Hyperbranched Bisphosphonate-Functional Polymers via Self-Condensing Vinyl Polymerization and Postpolymerization Multicomponent Reactions.

The synthesis of hyperbranched aminobisphosphonic acid polymers via reversible addition-fragmentation chain transfer (RAFT) self-condensing vinyl polymerization is reported. A novel acrylamide-functional chain transfer monomer is synthesized and characterized by 1 H and 13 C NMR spectroscopy, elemental analysis, and mass spectrometry. The monomer is subsequently copolymerized with an acrylamide monomer bearing a pendent amine group to create hyperbranched amine-functional polymers with degrees of branching dictated by changing the reaction stoichiometry. The aminobisphosphonate functional group is introduced via a 3-component Kabachnik-Fields reaction. An alternate functionalization of the amine polymers to create acid-degradable imine hydrogels is also employed. This work demonstrates the application of multicomponent reactions to RAFT-derived hyperbranched polymers and provides a new route to previously inaccessible polymers.

Monte Carlo Simulation on the Ternary Self-Condensing Vinyl Polymerization System with Semi-Batch Process

A Monte Carlo simulation on the ternary self-condensing vinyl polymerization system under the semi-batch mode is presented, where reactants are composed of comonomers (inimers and monomers) and multi-functionality core initiators. For the semi-batch process in the system, we mainly consider the influence of three feeding ways on the average polymeric quantities (weight-average molecular weight and polydispersity index) of hyperbranched polymers, where core initiators and comonomers are fed into the reactor at different time (or equivalently, at different conversions of vinyl group). As expected, the semi-batch process has a significant effect on the average properties of polymers, and therefore the feeding schedule can be predetermined to prepare polymers with desired properties.

Investigating the growth of hyperbranched polymers by self-condensing vinyl RAFT copolymerization from the surface of upconversion nanoparticles

The growth of hyperbranched polymers by self-condensing vinyl polymerization under RAFT conditions from the surface of upconversion nanoparticles is hindered by steric hinderance, but also increased termination and transfer reactions.

Kinetic model of hyperbranched polymers formed by self-condensing vinyl polymerization of inimers and trifunctional cores with different reactivities in a continuous-stirred tank reactor

A kinetic model is proposed to describe the formation of hyperbranched polymers, HBPs, by the self-condensing vinyl polymerization, SCVP, of inimers in a continuous stirred tank reactor, CSTR, with the addition of trifunctional cores. The dependence of the average degree of polymerization, DP, and the degree of branching, DB, on the Damköhler number, Da, is calculated by a generating function method. If the SCVP system has no core initiators, the flow in the CSTR may be stopped at a Da of approximately 0.5, which is caused by the formation of HBPs with ultrahigh molecular weights; then, the stable operating range becomes very narrow. The growth of HBPs in the SCVP can be retarded by adding the core with high reactivity into the CSTR. Therefore, formation of HBPs with ultrahigh molecular weights can be avoided even though the A groups are almost completely consumed at a high Da number. For example, the reduced weight-average DP is less than 1000 when the degree of conversion of the A group is 0.99, and only a few unreacted monomers remain in the product. The proposed model is useful for designing and optimizing a flow process for producing HBPs by the SCVP in a CSTR.

Efficient Liquid–Liquid Extraction of Benzene from Its Mixture with Cyclohexane by Utilizing Hyperbranched Polymeric Ammoniums Salts

A novel hyperbranched polymeric quaternary ammonium salt (HPQAS) with benzene rings in the structure (PVBC-TMA) was synthesized by self-condensing vinyl polymerization followed with quaternary amination reaction. Meanwhile, a hyperbranched polyamidoamine (PAMAM) was separately neutralized with different acids to produce the HPQASs without benzene rings. These HPQASs were dissolved in DMSO and used to extract benzene from its mixture with cyclohexane. The liquid–liquid equilibrium (LLE) data indicate that the HPQAS/DMSO mixture showed a higher selectivity coefficient (19.92) than DMSO (<15). PVBC-TMA having benzene rings showed higher extraction performance than the PAMAM salts without benzene rings, especially when the composition of benzene/cyclohexane is close to the azeotrope state. The cation−π and π–π interactions between the ammonium ion and the benzene ring in the HPQAS with benzene in the benzene/cyclohexane mixture were thought to be the mass transfer impetus for extracting benzene from its mixture with cyclohexane by utilizing the HPQASs. This was the first example of applying the hyperbranched polymeric ammonium in the separation of benzene/cyclohexane.

Self-Condensing Iodine Transfer Copolymerization for Highly Branched Polymers Using an in Situ Formed Chain Transfer Monomer

We reported a facile and effective method for the preparation of highly branched polymers by combining the concepts of self-condensing vinyl polymerization (SCVP) and iodine transfer polymerization (ITP). This procedure used a chain transfer monomer synthesized in situ from a commercially available chloride compound, p-chloromethylstyrene (CMS). The efficiencies of the halogen exchange from the alkyl chloride (−CH2Cl) to the alkyl iodide (−CH2I) at room and high temperature were studied using CMS and benzyl chloride as model halogenated compounds. The structures of the resulting polymer and the branching behavior were analyzed by nuclear magnetic resonance (NMR) spectroscopy and size-exclusion chromatography (SEC) equipped with a differential refractive index detector, a multiangle laser light scattering detector, and a viscometer detector. The model study using small molecules revealed that −CH2Cl could efficiently halogen exchange with sodium iodide (NaI) at both room and high temperature. The model lin...