Star-shaped Poly Research Articles

Synthesis and characterization of well-defined star-shaped poly(L-lactides)

The main goal of research is to study ring-opening polymerization of L-lactide in the presence of multifunctional alcohols in order to determine the optimal conditions for synthesis of star-shaped molecules of a predetermined well-defined structure, which is necessary for fine adjustment of material properties for various biomedical applications. The degree of polymerization of 3-, 4- and 6-arm star-shaped poly(L-lactides) varied from 10 to 100 monomer units per arm. It was found that under the same conditions polymerization rate and rate of initiation of co-initiator's hydroxyl groups can vary significantly depending on the structure and concentration of the selected alcohol. To prove the absence of cyclic, linear and comet-like structures in synthesized star-shaped PLLA, a variety of instrumental methods were used including GPC with triple detection, 1H NMR and MALDI. Study of properties and supramolecular structure of poly(L-lactides) using DSC and WAXS demonstrated that branching limits segmental mobility of the PLLA chains, especially for short arms, and hinders crystallization of star-shaped poly(L-lactides).

Effect of the Structure of Arms and Way of Their Attachment to Calix[4]arene on Self-Assembly Processes in Aqueous Solutions of Thermoresponsive Star-Shaped Poly(2-alkyl-2-oxazolines) and Poly(2-alkyl-2-oxazines)

Effect of the Structure of Arms and Way of Their Attachment to Calix[4]arene on Self-Assembly Processes in Aqueous Solutions of Thermoresponsive Star-Shaped Poly(2-alkyl-2-oxazolines) and Poly(2-alkyl-2-oxazines)

Delivery of Cas9-guided ABE8e into stem cells using poly(l-lysine) polypeptides for correction of the hemophilia-associated FIX missense mutation

The coagulation factor 9 gene (FIX) point mutation contributes to most hemophilia B cases, providing ideal gene correction models. Here we identified the frequent mutation G20519A (R226Q) in FIX, which resulted in many severe and moderate hemophilia B patients. This study aimed to investigate the effect of HDR and base editing in correcting FIX mutant. We first constructed HEK293 and liver-derived cell lines Huh7 cells stabling carrying mutated FIX containing G20519A (HEK293-FIXmut and Huh7-FIXmut). Then, CRISPR/Cas9-based homology-directed repair (HDR) and base editing were used for the correction of this mutated point. We used Cas9 nickase (nCas9) mediated HDR and the advanced base editor ABE8e to correct G20519A and then measured the concentration and activity of FIX. Furthermore, we used the star-shaped poly(lysine) gene nanocarriers to deliver the ABE8e correction systems into HEK293-FIXmut and Huh7-FIXmut stem cells to correct mutated FIX. As a result, we found that gRNAs directed inefficient HDR in correcting G20519A. The ABE8e corrected the mutation efficiently in both HEK293-FIXmut and Huh7-FIXmut stem cells. In addition, the star-shaped poly(lysine) carriers delivered non-viral vectors into stem cells efficiently. The nanocarriers-delivered ABE8e system corrected mutated FIX in stem cells, and the stem cells secreted active FIX in high concentration. In conclusion, our study provides a potential alternative for correcting mutated FIX in hemophilia B patients.

Physicochemical and biological properties of nanohydroxyapatite grafted with star-shaped poly(ε-caprolactone)

To overcome the disadvantages generated by the lack of interfacial bonding between hydroxyapatite nanocrystals (HAPN) and agglomeration of particles in the development of biodegradable nanocomposites a chemical grafting method was applied to modify the surface of HAPN through grafting of the three-arms star-shaped poly(ε-caprolactone) (SPCL) onto the nanoparticles. The chemical grafting of SPCL onto HAPN (SPCL-g-HAPN) has been investigated using Fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy (TEM), photoelectron spectroscopy, X-ray diffraction, zeta potential (ZP) and contact angle (CA). TEM micrographs of the SPCL-g-HAPN revealed the existence of hybrid organic/inorganic (O/I) nanoscale domains. The results of albumin (HSA) and fibrinogen (HFb) adsorption indicate resistance to HFb adsorption by SPCL-g-HAPN relatively to unmodified HAPN. The ZP and CA measurement suggest a heterogeneous topology for SPCL-g-HAPN likely due to the existence of hydrophobic-hydrophilic regions on the nanocomposite surface. The enzyme degradation by cholesterol esterase and lipase indicates that the rates of hydrolysis for SPCL-g-HAPN were very slow relative to the SPCL/HAPN blends. The in vitro biological studies showed that the human osteoblast-like cells (MG-63) cells had normal morphology and they were able to attach and spread out on SPCL-g-HAPN surfaces. A higher overall cellular proliferation was observed on SPCL-g-HAPN scaffolds compared to pure HAPN or SPCL materials.

Effect of Annealing at High Temperatures on the Morphology of Aqueous Solutions of Star-Shaped Poly(2-Isopropyl-2-Oxazoline) and Linear Poly(2-Ethyl-5,6-Dihydrooxazine)

Effect of Annealing at High Temperatures on the Morphology of Aqueous Solutions of Star-Shaped Poly(2-Isopropyl-2-Oxazoline) and Linear Poly(2-Ethyl-5,6-Dihydrooxazine)

Modified poly(L-lysine)-based structures as novel antimicrobials for diabetic foot infections, an in-vitro study

Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizations, morbidity and mortality. Skin traumas arise more frequently in those with diabetes or cardiovascular disease and in these settings, may be chronic with poorer outcomes including lower limb amputation. Treatment of chronic wound infection is challenging due to antibiotic resistance and biofilm formation by bacteria including S. aureus and P. aeruginosa, which are among the most frequent causative pathogens. Managing these challenging infections requires new molecules and modalities. Methods: We evaluated antimicrobial and anti-biofilm activity of star-shaped poly(L-lysine) (PLL) polymers against S. aureus and P. aeruginosa strains and clinical isolates recovered from wounds including diabetic foot wounds (DFW) in a Dublin Hospital in 2019. A star-shaped PLL polypeptide series, specifically G2(8)PLL 20, G3(16)PLL 10, G4(32)PLL 5 with variation in polypeptide chain length and arm-multiplicity, were compared to a linear peptide, PLL 160 with equivalent number of lysine residues. Results: All PLLs, including the linear polypeptide, were bactericidal at 1μM against S. aureus 25923 and P. aeruginosa PAO1, with log reduction in colony forming units/ml between 2.7-3.6. PLL 160 demonstrated similar killing potency against 20 S. aureus and five P. aeruginosa clinical isolates from DFW, mean log reductions: 3.04 ± 0.16 and 3.96 ± 0.82 respectively after 1 hour incubation. Potent anti-biofilm activity was demonstrated against S. aureus 25923 but for clinical isolates, low to moderate loss of biofilm viability was shown using PLL 160 and G3(16)PLL 10 at 50 μM ( S. aureus) and 200 μM ( P. aeruginosa) with high inter-isolate variability . In the star-shaped architecture, antimicrobial activity was retained with incorporation of 5-mer hydrophobic amino-acid modifications to the arms of the polypeptides (series G3(16)PLL 20-coPLT 5, G3(16)PLL 20-coPLI 5, G3(16)PLL 20-coPLP 5). Conclusion: These polypeptides offer structural flexibility for clinical applications and have potential for further development, particularly in the setting of diabetic foot and other chronic wound infections.

Synthesis and characterization of star-shaped block copolymers composed of poly(3-hydroxy octanoate) and styrene via RAFT polymerization

This study investigated a macro reversible addition fraction chain transfer (RAFT) agent based on three-arm hydroxylated star-shaped poly(3-hydroxy octanoate). The utilization of this star-shaped poly(3-hydroxy octanoate) macro-RAFT agent in the RAFT process resulted in efficient control in the preparation of star-shaped block styrene copolymers. Poly(3-hydroxy octanoate) (PHO) was reacted with diethanol amine (DEA) in order to obtain three-arm hydroxylated poly(3-hydroxy octanoate) (PHO-DEA). A carboxylic acid-functionalized RAFT agent (2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid) was reacted with the PHO-DEA in order to obtain a star-shaped PHO macro-RAFT agent (PHO-R2). A series of AB3 type PHO-polystyrene (PHO-PS) star-shaped block copolymers were obtained via the polymerization of styrene (S) using the PHO-R2 in toluene at 80 °C. The RAFT polymerization was seen to obey the polymerization kinetics of controlled free radical polymerization. The plasticizing effect of the PHO soft segments was influenced by the glass transition temperature (Tg) of polystyrene. This was clearly observed in the block copolymers. Moreover, it was clear that this plasticizing effect disappeared in the block copolymers as a result of the increase in polymerization time. The molar masses of the obtained copolymers increased in parallel with increases in the polymerization time. Structural, physiochemical, and thermal characterization of the obtained products was carried out using size-exclusion chromatography (SEC), proton nuclear magnetic resonance (1H NMR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA) techniques. The polymerization kinetics of the star-shaped block copolymers were also investigated in detail.

Synthesis and Hydrogelation of Star-Shaped Graft Copolypetides with Asymmetric Topology.

To study the self-assembly and hydrogel formation of the star-shaped graft copolypeptides with asymmetric topology, star-shaped poly(L-lysine) with various arm numbers were synthesized by using asymmetric polyglycerol dendrimers (PGDs) as the initiators and 1,1,3,3-tetramethylguanidine (TMG) as an activator for OH groups, followed by deprotection and grafting with indole or phenyl group on the side chain. The packing of the grafting moiety via non-covalent interactions not only facilitated the polypeptide segments to adopt more ordered conformations but also triggered the spontaneous hydrogelation. The hydrogelation ability was found to be correlated with polypeptide composition and topology. The star-shaped polypeptides with asymmetric topology exhibited poorer hydrogelation ability than those with symmetric topology due to the less efficient packing of the grafted moiety. The star-shaped polypeptides grafted with indole group on the side chain exhibited better hydrogelation ability than those grafted with phenyl group with the same arm number. This report demonstrated that the grafted moiety and polypeptide topology possessed the potential ability to modulate the polypeptide hydrogelation and hydrogel characteristics.

Enzymatic co-crosslinking of star-shaped poly(ethylene glycol) tyramine and hyaluronic acid tyramine conjugates provides elastic biocompatible and biodegradable hydrogels.

A combination of the viscoelastic properties of hyaluronic acid (HA) and the elastic properties of star shaped 8-arm poly(ethylene glycol) (8-arm PEG) was used to design in-situ forming hydrogels. Hydrogels were prepared by the enzymatic crosslinking of a partially tyramine modified 8-arm PEG and a tyramine conjugated HA using horseradish peroxidase in the presence of hydrogen peroxide. Hydrogels of the homopolymer conjugates and mixtures thereof were rapidly formed within seconds under physiological conditions at low polymer and enzyme concentrations. Elastic hydrogels with high gel content (≥95%) and high storage moduli (up to 22.4 kPa) were obtained. An in vitro study in the presence of hyaluronidase (100 U/mL) revealed that with increasing PEG content the degradation time of the hybrid hydrogels increased up to several weeks, whereas hydrogels composed of only hyaluronic acid degraded within 2 weeks. Human mesenchymal stem cells (hMSCs) incorporated in the hybrid hydrogels remained viable as shown by a PrestoBlue and a live-dead assay, confirming the biocompatibility of the constructs. The production of an extracellular matrix by re-differentiation of encapsulated human chondrocytes was followed over a period of 28 days. Gene expression indicated that these highly elastic hydrogels induced an enhanced production of collagen type II. At low PEG-TA/HA-TA ratios a higher expression of SOX 9 and ACAN was observed. These results indicate that by modulating the ratio of PEG/HA, injectable hydrogels can be prepared applicable as scaffolds for tissue regeneration applications.

Biodegradable Star-Shaped Poly(lactic acid): Synthesis, Characterization and Its Reaction Kinetics

Biodegradable four-arm star-shaped poly(lactic acid) (4sPLA) was synthesized from l-Lactic acid (l-LA) and pentaerythritol (PENTA), and the polymerization kinetics was studied. The effects of reaction time, reaction temperature and molar ratio on the polymerization of 4sPLA were discussed. The molecular structure of 4sPLA was characterized by Fourier transform infrared spectroscopy (FTIR) and 1H nuclear magnetic resonance spectra (1H-NMR). The results showed that the optimum reaction conditions were as follows: the molar ratio of l-LA to PENTA was 12:1, and the polymerization reaction occurred at 160 ℃ for 5 h. Gel permeation chromatography method was used to determine the polymerization kinetics of 4sPLA consistent with the first-order reaction kinetics.

Polymerizations of 2-(Trimethylsilyl)ethanesulfonyl-activated aziridines

A novel N-sulfonyl aziridine, N-((2-(trimethylsilyl)ethyl)sulfonyl)-2-methyl-aziridine (SES-MeAz) was synthesized, and its controlled anionic ring-opening polymerization to form poly(SES-MeAz) studied. The desulfonylation of poly(SES-MeAz)s can be achieved under mild conditions, with tetrabutylammonium fluoride (TBAF) to form polypropylene imine (PPI), although purification of the PPI was not completely successful. The block copolymer p(pTs-MeAz)-b-p(SES-MeAz), (pTs-MeAz = N-para-tosyl-2-methyl-aziridine) was prepared by a sequential polymerization. The desulfonylation of the block copolymer is the first example of the selective removal of a sulfonyl protecting group from a poly(sulfonylazirdine) block copolymer and this is the first formation of a polysufonylaziridine-block-polypropylene imine copolymer. Three-armed star-shaped poly(SES-MeAz)s were also successfully synthesized and exhibited improved solubility compared with linear poly(SES-MeAz)s.

Modified poly(L-lysine)-based structures as novel antimicrobials for diabetic foot infections, an in-vitro study.

Background: Wound infections occur as sequelae to skin trauma and cause significant hospitalizations, morbidity and mortality. Skin traumas arise more frequently in those with diabetes or cardiovascular disease and in these settings, may be chronic with poorer outcomes including lower limb amputation. Treatment of chronic wound infection is challenging due to antibiotic resistance and biofilm formation by bacteria including S. aureus and P. aeruginosa, which are among the most frequent causative pathogens. Managing these challenging infections requires new molecules and modalities. Methods: We evaluated antimicrobial and anti-biofilm activity of star-shaped poly(L-lysine) (PLL) polymers against S. aureus and P. aeruginosa strains and clinical isolates recovered from wounds including diabetic foot wounds (DFW) in a Dublin Hospital in 2019. A star-shaped PLL polypeptide series, specifically G2(8)PLL 20, G3(16)PLL 10, G4(32)PLL 5 with variation in polypeptide chain length and arm-multiplicity, were compared to a linear peptide, PLL 160 with equivalent number of lysine residues. Results: All PLLs, including the linear polypeptide, were bactericidal at 1μM against S. aureus 25923 and P. aeruginosa PAO1, with log reduction in colony forming units/ml between 2.7-3.6. PLL 160 demonstrated similar killing potency against 20 S. aureus and five P. aeruginosa clinical isolates from DFW, mean log reductions: 3.04 ± 0.16 and 3.96 ± 0.82 respectively after 1 hour incubation. Potent anti-biofilm activity was demonstrated against S. aureus 25923 but for clinical isolates, low to moderate loss of biofilm viability was shown using PLL 160 and G3(16)PLL 10 at 50 μM ( S. aureus) and 200 μM ( P. aeruginosa) with high inter-isolate variability . In the star-shaped architecture, antimicrobial activity was retained with incorporation of 5-mer hydrophobic amino-acid modifications to the arms of the polypeptides (series G3(16)PLL 20-coPLT 5, G3(16)PLL 20-coPLI 5, G3(16)PLL 20-coPLP 5). Conclusion: These polypeptides offer structural flexibility for clinical applications and have potential for further development, particularly in the setting of diabetic foot and other chronic wound infections.

Star-shaped poly(ε-caprolactones) with well-defined architecture as potential drug carriers

The present study reports the potential application of star-shaped poly(?-caprolactones) with different number of arms as new drug delivery matrix. Linear and star-shaped PCL ibuprofen loaded microspheres were prepared using oil-in-water (o/w) solvent evaporation technique and characterized with FTIR, DSC, XRD and SEM analysis. High yield, encapsulation efficiency and drug loadings were obtained for all microspheres. FTIR analysis revealed the existence of interactions between polymer matrix and drug, while the DSC analysis suggested that drug was encapsulated in an amorphous form. SEM analysis confirmed that regular, spherical in shape star-shaped microspheres, with diameter between 80 and 90 ?m, were obtained, while quite larger microspheres, 110 ?m, were prepared from linear PCL. The advantage of using starshaped PCL microspheres instead of linear PCL was seen from drug release profiles which demonstrated higher amount of drug released from star-shaped polymer matrix as a consequence of their branched, flexible structure. Microspheres prepared from the polymers with the most branched structure showed the highest amount of the released drug after 24 h. Finally, cytotoxicity tests, performed using normal human fibroblasts (MRC5), indicated the absence of cytotoxicity at lower concentrations of microspheres proving the great potential of star-shaped PCL systems in comparison to linear ones.

A Novel Grafting-Onto Approach to the Facile Synthesis of Star-Shaped Poly(2-Oxazoline)S with Calix[4]Arene Core as Curcumin Nanocarriers

A Novel Grafting-Onto Approach to the Facile Synthesis of Star-Shaped Poly(2-Oxazoline)S with Calix[4]Arene Core as Curcumin Nanocarriers

Synthesis and enhanced nonlinear optical performance of phthalocyanine indium polymers with electron-donating group porphyrin by efficient energy transfer

In this study, a phthalocyanine indium (InPcOH) and three porphyrin derivatives (Por2a, Por2b, Por2c) were successfully synthesized. Three kinds of novel four-arm star-shaped poly(propylene oxide) (PPO) with core of InPcOH and chain-end of porphyrin derivatives, named InPc-(PPOx-Por2n)4 (n = a-c), were achieved through the InPcOH as initiator by ring-opening polymerization. From fluorescence spectra, InPc-(PPOx-Por2n)4 polymers revealed weaker emission intensity at 704 nm in comparison with InPc-(PPO29)4, proving energy transfer (ET) pathway from Por2a-2c to InPc, which could be established by theoretical study. Due to ET pathway, InPc-(PPOx-Por2n)4 polymers showed stronger nonlinear optical (NLO) performance than InPc-(PPO29)4 polymer. Among InPc-(PPOx-Por2n)4, InPc-(PPO33-Por2b)4 obtained the most outstanding NLO performance exhibiting imaginary third-order susceptibility (Im[χ(3)]) of 6.25 × 10−11 esu, which could ascribe the efficient ET pathway from Por2b to InPc based on the appropriate spatial structure and small energy gap of Por2b. Moreover, the InPc-(PPO33-Por2b)4/polymethyl methacrylate (PMMA) composites were prepared for applying actually, and it displayed a prominent Im[χ(3)] value of 22.4 × 10−11 esu and an outstanding limiting threshold of 0.14 J/cm2. The remarkably enhanced NLO performance exhibited by InPc-(PPO33-Por2b)4/PMMA composites in comparison with that in methyl methacrylate solution prove a feeblish aggregation effect in PMMA matrix, which indicate the great potential of our polymers for real application in NLO field. This research could furnish a novel designing approach in terms of NLO materials that exhibit great performance.

Star-shaped Poly(hydroxybutyrate)s from bio-based polyol cores via zinc catalyzed ring-opening polymerization of β-Butyrolactone

The ring-opening polymerization (ROP) of cyclic esters using multifunctional initiators is an efficient methodology that allows the preparation of polyesters with well-defined architectures. Here a series of star-shaped poly(β-hydroxybutyrates) (PHBs) has been synthesized by ROP of β-butyrolactone (BBL) with an amido-oxazolinate zinc catalyst. The star-shaped structure is constructed via a core-first approach, in which several bio-based multifunctional alcohols serve as the initiator for ROP. Specifically, three-, four-, and multi-armed star polymers are obtained and characterized by various techniques including NMR, GPC, TGA, and DSC, and the incorporation of the core structure in the star-shaped PHBs has been confirmed. The thermal properties can be modified by changing the arm number and arm length of PHBs, and the thermal stability decreases as the number of arms increases when they have the same arm lengths. The wetting behavior determined from AFM studies demonstrates a minimum in the macroscopic contact angle as a function of the number of arms of a star-shaped PHB.

Effective End-Group Modification of Star-Shaped PNVCL from Xanthate to Trithiocarbonate Avoiding Chemical Crosslinking.

In this study, six-arm star-shaped poly(N-vinylcaprolactam) (PNVCL) polymers prepared by reversible addition–fragmentation chain transfer (RAFT) polymerization were subjected to aminolysis reaction using hexylamine. Chemically crosslinked gels or highly end-functionalized star polymers can be obtained depending mainly on the type of solvent used during the transformation of the RAFT functional group. An increase in the viscosity of the solution was observed when the aminolysis was carried out in THF. In contrast, when the reaction was conducted in dichloromethane, chain-end thiol (PNVCL)6 star polymers could be obtained. Moreover, when purified (PNVCL-SH)6 star polymers are in contact with THF, the gelation occurs in just a few minutes, with an obvious increase in viscosity, to form physical gels that become chemically crosslinked gels after 12 h. Interestingly, when purified (PNVCL-SH)6 star polymers were stirred in distilled water, even at high aqueous solution concentration (40 mg/mL), there was no increase in the viscosity or gelation, and no evident gels were observed. The analysis of the hydrodynamic diameter (Dh) by dynamic light scattering (DLS) did not detect quantifiable change even after 4 days of stirring in water. On the other hand, the thiol groups in the (PNVCL-SH)6 star polymers were easily transformed into trithiocarbonate groups by addition of CS2 followed by benzyl bromide as demonstrated by UV-Vis spectroscopical analysis and GPC. After the modification, the (PNVCL)6 star polymers exhibit an intense yellow color typical of the absorption band of trithiocarbonate group at 308 nm. To further demonstrate the highly effective new trithiocarbonate end-functionality, the PNVCL polymers were successfully chain extended with N-isopropylacrylamide (NIPAM) to form six-arm star-shaped PNIPAM-b-PNVCL block copolymers. Moreover, the terminal thiol end-functionality in the (PNVCL-SH)6 star polymers was linked via disulfide bond formation to l-cysteine to further demonstrate its reactivity. Zeta potential analysis shows the pH-responsive behavior of these star polymers due to l-cysteine end-functionalization. By this using methodology and properly selecting the solvent, various environment-sensitive star polymers with different end-groups could be easily accessible.

Graphoepitaxy of Symmetric Six‐Arm Star‐Shaped Poly(methyl methacrylate)‐block‐Polystyrene Copolymer Thin Film

Front Cover: By utilizing directed self-assembly of a lamellar forming six-arm star-shaped poly(methyl methacrylate)-block-polystyrene copolymer [(PMMA-b-PS)6] thin film confined within trenches, Jaeup U. Kim, Jin Kon Kim, and co-workers successfully fabricate two or more different nanopatterns including nanotubes and straight lines on a single substrate by carefully controlling the trench width and the affinity between the blocks and the trench wall. This work can be found in article number 2100411.

A Hydrophobic Derivative of Ciprofloxacin as a New Photoinitiator of Two-Photon Polymerization: Synthesis and Usage for the Formation of Biocompatible Polylactide-Based 3D Scaffolds.

A hydrophobic derivative of ciprofloxacin, hexanoylated ciprofloxacin (CPF-hex), has been used as a photoinitiator (PI) for two-photon polymerization (2PP) for the first time. We present, here, the synthesis of CPF-hex and its application for 2PP of methacrylate-terminated star-shaped poly (D,L-lactide), as well a systematic study on the optical, physicochemical and mechanical properties of the photocurable resin and prepared three-dimensional scaffolds. CPF-hex exhibited good solubility in the photocurable resin, high absorption at the two-photon wavelength and a low fluorescence quantum yield = 0.079. Structuring tests showed a relatively broad processing window and revealed the efficiency of CPF-hex as a 2PP PI. The prepared three-dimensional scaffolds showed good thermal stability; thermal decomposition was observed only at 314 °C. In addition, they demonstrated an increase in Young’s modulus after the UV post-curing (from 336 ± 79 MPa to 564 ± 183 MPa, which is close to those of a cancellous (trabecular) bone). Moreover, using CPF-hex as a 2PP PI did not compromise the scaffolds’ low cytotoxicity, thus they are suitable for potential application in bone tissue regeneration.

Electrochemical topological transformation of polysiloxanes

Coupling reactions between polymers are an important class of chemical modifications for changing, enhancing, and tuning the properties of polymeric materials. In particular, transformation of polymer topologies based on efficient, facile and less wasted coupling reactions remains a significant challenge. Here, we report coupling reactions based on electrochemical oxidation of 2,4,5-triphenylimidazole into a 2,4,5-triphenylimidazolyl radical and its spontaneous dimerization into hexaarylbiimidazole. Based on this chemistry, electrochemical topological transformation (ETT) and electrochemical chain extension have been realized with siloxane-based oligomers and polymers. Moreover, this approach enables one step ETT of star-shaped poly(dimethyl siloxane)s (PDMSs) into network PDMSs, running in an ionic liquid solvent and requiring no purification steps.