Journal of Polymer Science Part A: Polymer Chemistry

In this work, a new paradigm to functionalize poly(ɛ-caprolactone) using α,ω-epoxy esters is demonstrated. The model α,ω-epoxy ester—ethyl 2-methyl-4-pentenoate oxide (EMPO) was synthesized via epoxidation and its incorporation into the PCL backbone via ring-opening copolymerization was investigated. Statistical, random copolymers of CL and EMPO were obtained and copolymerization parameters were determined to be 1.31 and 0.01, for ɛ-caprolactone and EMPO, respectively.

Superparamagnetic and thermoresponsive hybrid nanoparticles composed of poly[di(ethylene glycol) ethyl ether acrylate-co-(oligoethylene glycol) methyl ether acrylate] shell and magnetic Fe₃O₄ core were synthesized via surface-mediated RAFT polymerization. The hybrid nanoparticles exhibited excellent magnetic susceptibility (M_s ≅ 55.1–19.4 emu/g) and showed a temperature-responsive behavior as the temperature changed between 25 and 40 ^°C.

Novel skipped-π polymers comprising π-components connected with 2-substituted trimethylene tethering units that exist as stair-like stacking substructures were synthesized and found to exhibit bathochromically shifted, broadened UV absorption with a unique lower-energy absorption band and largely red-shifted fluorescent emission owing to the extended π-conjugation resulting from through-space π–π interactions in the ground and excited states.

Solvent-free nanofluid and prepolymer are air cured to produce a tough and transparent clearcoat. The solvent-free nanofluid is prepared by surface modifying nanosilica (9–10 nm) with an ionic liquid type of organic salt and with reactive isothiocyanate. It is dissolved in a novel poly(propylene oxide) isophorone diisocyanate prepolymer, coated, and cured with atmospheric moisture at room temperature. The proportion of nanofluid (1-16%) tunes the moduli and produces nanocomposites harder (2×) to softer (½×) than the control.

Well-defined PFMA was successfully synthesized by reversible addition fragmentation chain-transfer (RAFT) polymerization technique using CDTSPA and 4 cyano-4-(thiobenzoylthio) pentanoic acid (CTBPA) as different chain transfer agents (CTA). Thereafter, reactive furfuryl group of PFMA was used to prepare crosslinked polymeric materials via DA reaction using different bismaleimides. These crosslinked polymers showed thermally amendable properties through DA and retro-DA click reaction only by applying temperature.

An atom transfer radical polymerization (ATRP) initiator has been chemically immobilized on the surface of carbon hard spheres (CHSs) in only one step by a radical trapping method. These initiator immobilized CHSs are used to graft polystyrene and poly(methyl methacrylate) chains via surface-initiated ATRP. The resultant grafted CHSs are covered by a dense uniform film of grafted polymers. The thickness of grafted polymer is controlled by tuning the amount of sacrificial free initiator during graft polymerization.

N-Vinylcaprolactam and di(ethylene glycol) methyl ether methacrylate are copolymerized in high yield via miniemulsion polymerization. The lower critical solution temperature (LCST) of the obtained linear copolymers is controlled by their composition and the concentration of drugs in the solutions.

Poly(1,3-pentadiene) synthesized by cationic polymerization of 1,3-pentadiene with ^tBuCl/TiCl₄ initiating system contains only homo and mixed dyads with trans−1,4-, trans−1,2-, and cis−1,2-structures with regular and inverse (head-to-head or tail-to-tail) enchainment, whereas cis−1,4- and 3,4-units are totally absent.

Various bis(cyclic carbonates) were synthesized by thiol–ene coupling. Five- and six-membered cyclic carbonates and thiocarbonates were compared to yield nonisocyanate polyurethanes (PUs) with various amines. Synthesized PUs exhibit low T_g from −29 to 19 °C and high molar masses, interesting properties for coating applications.

This work investigates polymerization behavior of regioisomeric vinyl triazole monomers with styrene. The results obtained for the reactivity ratio between regioisomers show exceptionally different polymerization behavior highlighting the effects of the electronic and steric factors of these regioisomeric monomers. In the absence of any steric effects or electronic effects, a random copolymer is formed.

Novel thermo-responsive PNIPAAm-b-PLLA-b-PNIPAAm triblock copolymers were prepared by ATRP of NIPAAm with Br-PLLA-Br macroinitiator. Copolymers with excellent control over the molecular weight and narrow dispersity were obtained under mild condition. LCST was detected between 32.1 and 32.8 °C. Micelles are prepared by self-assembly of amphiphilic copolymers in aqueous medium. The micelles exhibit a thermo-responsive behavior, showing great potential as carrier of drugs.

Butyl rubber-poly(ethylene oxide) (PEO) graft copolymers were synthesized through the derivatization of the isoprene moieties in butyl rubber containing high (7 mol %) isoprene content. Films of these graft copolymers exhibited interesting properties such as high stability in aqueous solution and resistance to the growth of cells at high PEO content. The copolymers also formed stable nanosized assemblies in aqueous solution and their size could be controlled through their preparation method.

A “rigid-rod bottle-brush” type conjugated copolymer–fullerene composite has been obtained through “three-point” complementary hydrogen bonding interactions between a selectively functionalized polythiophene block copolymer and a novel thymine tethered fullerene derivative. Such non-covalent interactions allow facile tuning of fullerene loading percentages and the relatively high binding strengths lead to solid-state morphology stabilization. Solar cells fabricated from such “rigid-rod bottle-brush” composite were studied in detail. Benchmark P3HT/PCBM BHJ device performance and thermal stability could be improved by adding a few percentage of such polymer/fullerene composite.

CO₂ capturing and releasing behavior of a linear polyamidine having a hexamethylene linker has been investigated in solution as well as in the solid state. The polyamidine captures and releases CO₂ in an aqueous solution to the same level as a common polyamine, polyethyleneimine. In contrast, a binary system consisting of the polyamidine and polyethylene glycol absorbs CO₂ much more efficiently than that with the polyethyleneimine and polyethylene glycol.

Electrochemical polymerization in crystal followed by polymerization in cholesteric liquid crystal allows production of crystal-liquid crystal ordered electro-optically active polymer. The polymer shows photonic insect like metallic reflection. The metallic color is tunable via electrochemical redox process.

Amino functionalized multiwall carbon nanotubes (MWNTs) are obtained by two ways: conventional one-step method (Di-MWNT) and the improved two-step approach (NH₂-MWNT). Comparing with Di-MWNT, NH₂-MWNT shows more excellent dispersion and better compatibility in the polyimide (PI) matrix. NH₂-MWNTs can form connected network structure throughout the PI matrix, which makes the NH₂-MWNT/PI composite film having good conductivity, mechanical property, and thermal stability.

Three different vinylimidazole based asymmetric ion pair comonomers (IPCs) free from nonpolymerizable counter ions have been synthesized, characterized, and polymerized by different polymerization techniques including ATRP and RAFT. This investigation provides insight to the polymerization behavior of each individual component of these asymmetric IPCs and its effects on composition and solubility of polymer produced. The IPCs studied here are high temperature ionic liquids and the polymers synthesized from these IPCs are highly ionic in nature and possess very strong intermolecular interactions. This highly ionic interaction is exploited to synthesize ionically crosslinked PMMA.

Biohybrid nanogels prepared synergistically by recapitulation of well-evolved biological mechanism with tailorable properties can be variedly used for different applications ranging from therapeutics to catalysis. Herein, we illustrate the recent developments in the fields of these biohybrids with elucidation of their potential application.

4′-Nonafluorobutyl styrene (1) was synthesized and polymerized by conventional and controlled radical polymerizations namely iodine-transfer polymerization (ITP) technique in the presence of 1-iodoperfluorohexane. The kinetics of radical homopolymerization of (1) led to its k_p²/k_t value. Đ-values of these fluoropolymers were different (1.30 from conventional way and 1.15 from ITP). Thermal properties and surface energies of these homopolymers achieved for both techniques were discussed and evidenced the influence of Đ-values on their surface properties.

Crosslinking copolymerization of butyl methacrylate with a small amount of divinylbenzene was carried out using single-electron transfer-living radical polymerization initiated with CCl₄ and catalyzed by Cu(0)/N-ligand in N,N-dimethylformamide to produce a highly oil-absorbing gel. The polymerization followed first-order kinetics for both linear and crosslinking polymerization before gelation. Under optimal conditions, oil absorption of the prepared gel to chloroform could reach 42.1 g·g⁻¹.

Thermoresponsive amphiphilic linear–dendritic block copolymers, composed of hydrophilic poly(N-vinylcaprolactam) chains and hydrophobic dendritic aromatic polyamide, have been designed and prepared by reversible addition fragmentation chain transfer polymerization. Their lower critical solution temperatures (LCSTs) depend on the generation of the dendrons and the concentrations of the copolymer solutions. They are capable of self-assembling into nanospherical micelles in water. A sustained drug release is achieved from the copolymer micelles, which is accelerated when the environmental temperature is raised slightly above the LCST.

Efficient SET-LRP of oligo(ethylene oxide) methyl ether methacrylate (OEOMA) in DMSO, and binary mixtures of DMSO with H₂O in the absence and presence of air is reported. Both OEOMA and the initiator self-assemble in water into micellar aggregates and vesicles.

Poly(propylene-co-1-pentene-co-1-hexene) terpolymers are synthesized and polymerization activity is evaluated as well as the molecular characteristics of the resulting materials. Moreover, the trigonal polymorph is developed in those terpolymers with the highest overall comonomers content independently of the ratio between both comonomers. Crystallization kinetics is, however, slowed down as 1-hexene concentration is increased.

(E)-2-methyl-1,3-pentadiene (2MP) was polymerized with heterogeneous and homogeneous neodymium catalysts, obtaining isotactic and syndiotactic cis-1,4 polymers, respectively. A tentative interpretation is given for the mechanism of the formation of these stereoregular polymers and a complete NMR characterization of the cis-1,4-syndiotactic poly(2MP) is reported.

Well-defined amphiphilic multiblock copolymers PDMAEMA-b-P(IBMD-co-PDO)-b-PEG-b-P(IBMD-co-PDO)-b-PDMAEMA [PDMAEMA-PIBMD-PPDO-PEG], based on poly(2-(dimethylamino)ethyl methacrylate) block (PDMAEMA), poly(3(S)-isobutyl-morpholine-2,5-dione-co-p-dioxanone) block (P(IBMD-co-PDO)), and poly(ethylene glycol) block (PEG) were successfully synthesized by combination of ring-opening polymerization (ROP) (using 3(S)-isobutyl-morpholine-2,5-dione and p-dioxanone initiated by hydroxyl end of PEG) and atom transfer radical polymerization (ATRP). These multiblock copolymers PDMAEMA-PIBMD-PPDO-PEG could readily self-assemble into nanosized microspheres in PBS, combined model drugs ibuprofen (IBU) with doxorubicin (DOX) were loaded successfully into these microspheres, which exhibited high LC, EE, and drug release behavior in PBS. It can be envisaged that these copolymer systems are promising candidates for controlled release application.

Copper-mediated controlled radical polymerization (CRP) has tremendous potential as a synthetic tool for value-added materials. Commercial viability of the technology hinges on decreasing production costs by reducing the concentration of copper metal used, and increasing production efficiency. In this highlight article, advancements in copper-mediated CRP chemistry and process development will be presented, with a particular focus on copper(0)-mediated CRP in continuous flow reactors as an environmentally friendly and economically viable platform for large-scale production of novel polymeric materials.

New naphtho[1,2-b:5,6-b′]dithiophene-containing donor-acceptor conjugated copolymers have been designed and developed for application in polymer solar cells. The effect of different electron-acceptor groups on the optoelectronics and photovoltaic properties of the copolymers have been evaluated and described.

Thermally responsive microgels have been widely investigated in the context of controlled release applications. In this feature article, we outline key design parameters associated with engineering responsive microgels for drug delivery and discuss several recent examples to illustrate how these principles have been applied to the synthesis of microgels or microgel-based composites. The existing gap between the fascinating properties observed in the lab and the practical use of microgels in the clinic needs to be bridged.

The use of poly (N-isopropylacrylamide) (pNIPAm)-based microgels for water remediation and sensing/biosensing is highlighted. For water remediation, the microgels are used as a sorbent, which are capable of removing organic molecules from water. Sensing applications rely of the fabrication of pNIPAm microgel-based devices, which exhibit visual color. We show that the color of the devices depends on solution temperature, pH, and glucose concentration. This highlight also details our fundamental studies of these color tunable materials.

Reported here are the synthesis and characterization of new homopolypeptides with PPII structure. These biopolymers were obtained by ring-opening polymerization of silaproline (silylated analogue of proline) N-carboxyanhydride. Homopolysilaprolines were characterized by NMR, MALDI-Tof and circular dichroism.

Well-controlled dispersion RAFT polymerization of styrene in the alcohol/water mixture mediated with the brush macro-RAFT agent of poly[poly(ethylene oxide) methyl ether vinylphenyl-co-styrene] trithiocarbonate is performed and various block copolymer nano-objects such as nanospheres, worms, vesicles, and large-compound-micelle-like particles are prepared.

The controlled design of three series of antibacterial amphiphilic polycations such as PTBAEMA, PTBAEMA-b-PEGMA, and PTBAEMA-co-PEGMA were carried out by SET-LRP. Their antibacterial properties were evaluated against E. coli and expressed as MICs, while for the PCU- modified film surfaces, depicted as percent killing. Upon interaction with bacterial cells, these polycations mimic AMPs and causes disruption of cytoplasmic membranes. The biocompatibility against mammalian RBCs indicated that PEGMA protect mammalian cell membranes from severe action, and also because of lesser number of cationic charges on its surface. Therefore, these materials can serve as useful candidates in future as pharmaceuticals.

Stimuli-responsive star polymers with various numbers of arms and compositions can be generated by different polymerization techniques, that is, anionic and controlled radical polymerization (CRP). Their stimuli-responsive behavior in solution or immobilized on a substrate as well as their potential application are reviewed.

Amphiphilic PEtOz-b-PMCL and PEtOz-b-PBCL showed low cytotoxicity. DOX-loaded micelles facilitated HeLa cell uptake of DOX, and DOX was able to reach intracellular compartments and enter the nuclei by endocytosis. PEtOz-b-PM(B)CL can be used as the drug delivery.

Three series of binary copolymers with high-molecular weights have been prepared via free-radical polymerization based on 2, 5-bis[(4-alkoxyphenyl)oxycarbonyl]styrenes (M-OCm, m is the number of the carbons of alkyl tails, m = 1, 4, and 18). The phase behaviors of copolymers were studied by DSC, POM, and 1D WAXD. The experiment results showed that the self-assemble behavior of mesogen-jacketed liquid crystalline copolymers was strongly depended on the composition and the alkyl length due to the competing among the steric effect, the microphase separation, and the driving force of the entropy.

Microgels can switch their chemical and physical properties on external stimulus, and the colloidal behavior of microgels is strongly affected by interparticle interactions between them. In this paperarticle, we introduce Janus microgels and oscillating microgels developed by our group. In particular, the interparticle interactions of these microgels are discussed.

Dendron-–polymer conjugates derived from water -soluble and biocompatible polyethylene glycol polymers and biodegradable polyester dendrons were synthesized using the Diels-–Alder ‘“click'” chemistry. Furan -protected- maleimide containing end-functionalized polyethylene glycol (PEG) polymers were reacted with polyester dendrons containing an anthracene group at focal point. The method provides facile preparation of multivalent PEG polymers amenable to further functionalization.

A novel organic selenium compound (diselenocarbonates) was successfully used as RAFT agent for the polymerization of VAc, which provide the way for the incorporation of selenium into polymer under the controlled manner.

Polyethylene glycol (PEG)-based hydrogels exhibit that the equilibrium swelling ratios are changed by varying the length of PEG chains of PEG dimethacrylate, functional monomer, porogenic solvents, and its compositions. Furthermore, the swelling/shrinking behaviors of PEG-based hydrogels were affected by the environmental condition of aqueous solution, in fact the hydrogels were greatly shrunk (to one-fifth volume) using a di-ionic solute through the ionic interaction toward ionic groups in hydrogels. In addition, the specific shrinking behavior to diamine compounds was also observed in response to pH change. In other words, the hydrogels are responsively swelling/shrinking toward pH and molecular recognitions.

Microgels are crosslinked soft particles with a three-dimensional network structure that are swollen in a good solvent. Among them, pNIPAM based microgel received great attention due to their unique thermal transition property. Especially, the tunable property and excellent biocompatibility make pNIPAM microgels desirable in biomedical field. The roles of microgels, such as drug delivery vector or cell matrix is highly correlated with their physical properties, including the core-shell structure, the swollen to shrunk transition and so on.

Photocrosslinkable optical waveguides consisting of well-defined GMA/PFS random copolymers synthesized by NMP are fabricated in this study. As features ∼1 μm were approached, lower polymer dispersity (M¯_w/M¯_n) afforded by NMP reduced the line edge roughness (LWR).

Highly fluorinated phosphonium salts bearing a polymerizable group were synthesized and incorporated into photopolymerizable systems. This imparted hydrophobic behaviour to the cured films despite the presence of ionic charges. A structure-activity relationship was found between the structure and architecture of the phosphonium core and its hydrophobic performance. TOF-SIMS analysis confirmed the presence of the fluorinated species at the polymer/air interface.

Polypeptides are nature's precision polymers that exhibit sequence specific functions such as catalysis and molecular recognition. Other properties such as secondary structure formation or smart responses to external triggers do require defined but not sequence specific polymers. Polypeptoids have been shown to be able to address these issues. A comprehensive overview on the different synthetic routes towards molecularly defined polypeptoids and polypeptoids with narrow dispersities as well as on their properties is given.

Novel helical poly(phenylacetylene)s with amino-functionalized cinchona alkaloid pendant groups connecting to the phenyl rings through a sulfonamide linkage were synthesized. The optically active sulfonamide-linked polymers adopted a helical conformation with an excess of one-handedness, and efficiently catalyzed the enantioselective aza-Michael addition of aniline to chalcone, and thus affording a remarkably higher enantioselectivity (up to 86% ee) than those of the corresponding monomers and nonhelical polymers.

Novel cyclic olefin copolymers (COCs) with high glass transition temperature and high thermal stability have been successfully obtained in this work via effective copolymerization of ethylene and bulky cyclic olefin.

A series of molecular weights and compositions tunable conjugated rod–rod block copolymers, P3HT-b-PPI, has been synthesized in the presence of Ni(dppp)Cl₂ as a single catalyst in one pot. Spherical aggregates and amorphous state were observed in tetrahydrofuran and CHCl₃ solutions, respectively. Atomic force microscopy revealed that the block copolymers could self-assemble into nanofibrils from CHCl₃ on the substrate. The unique features warrant the resultant copolymers' potential study in organic photovoltaic and other electronic devices.

A series of electroactive polyetherimides (PEIs) were synthesized from 4,4′'-bis(p-aminophenoxy)triphenylamine and various aromatic dianhydrides. Insertion of a phenoxy spacer between the triphenylamine unit and the imide ring decreases the oxidation potentials and increases the electrochemical stability of the polyimides. All the PEIspolyetherimides exhibit an ambipolar electrochemical and electrochromic behavior. The PEIpolyetherimide films exhibit reversible electrochemical oxidation accompanied by strong color changes that can be switched through modulation of the applied potential.

Two phenazine-based donor–acceptor copolymers (P1 and P2) were synthesized. Although the effects of the position of alkoxy groups attached to the phenazine unit on optical and electrochemical properties of copolymers were limited, very different copolymer/PC₇₁BM blend morphologies and photovoltaic performance were observed.

A series of side chain liquid -crystal polymers, the poly [6-[4-(4′′-n-alkyl benzoateazo)phenoxy]-hexylmethacrylate]s (PMazoCOOR_m, m is the number of the carbons of alkyl tails, m = 1, 2, 3, 4, 5, 6, 8, 10, 14, and 18) have been prepared by two synthetic methods. The phase behaviors of the polymers have been investigated by a combination of techniques including differential scanning calorimetry, polarized optical microscopy, and 1D small-angle X-ray scattering. The results of the experiments results indicated that the length of alkyl tails played an important role in the phase behaviors of these polymers.

The poly(N-isopropylacrylamide-methylacrylate acid) (poly(NIPAAm–-MAA))/Fe₃O₄/poly(NIPAAm-MAA) two-shells magnetic composite hollow latex particles were synthesized by four-steps reaction. Many factors such as reactant concentration, monomer ratio, and pH value influence the morphology of composite latex particles significantly. A transmission electron microscopy was used to observe the appearance morphology and cross-section morphology of magnetic composite latex particles that are shown as (a) and (b) respectively. The results appear that the latex particles possessed a hollow structure.

A new poly(3-dodecyltellurophene) (P3DDTe) was synthesized through a Suzuki polymerization reaction and the optoelectronic properties of P3DDTe were described.

Periodic and random ethylene–ethyl acrylate copolymers were synthesized via acyclic diene metathesis (co)polymerization. Differential scanning calorimetry results indicated that copolymers with low ethyl acrylate content and regular primary structure exhibited better crystallinity.

Well-defined polymethylene-b-polystyrene (PM-b-PS) diblock copolymers were synthesized via a combination of polyhomologation of ylides and reversible addition-fragmentation chain-transfer polymerization. The terminal thiocarbonylthio group of PM-b-PS was efficiently transformed into thiol group by aminolysis. The microspheres and microfibers of PM₁-b-PS₃ were fabricated by an electrospinning process using dimethylformamide and DMF-CHCl₃ as solvents and observed by SEM.

Novel bromine-functionalized photocrosslinkable low-bandgap copolymers, PBDTTT-Br25 and PBDTTT-Br50, were synthesized via Stille cross-coupling polymerization for the purpose of stabilizing the film morphology in polymer solar cells (PSCs). The formation of large aggregations of fullerene was suppressed in polymer:fullerene blend films even after prolonged thermal annealing, and the stability of the device was enhanced when compared with cells based on noncrosslinkable PBDTTT. Our approach paves a way toward solvent-robust and operation-stable PSCs.

Hyperbranched vinyl polymers with high degrees of branching and numerous functional pendent allene groups have been successfully prepared via RAFT polymerization of a new allene-derived asymmetrical divinyl monomer.

Copolymers of PSt-co-AM were synthesized by SET LRP 25 °C in DMF using CCl₄ as initiator with Fe(0)/TMEDA catalytic system. SET LRP technique was successfully developed by the group of Percec with the aim of reducing the catalyst concentration and the polymerization was performed at an ambient temperature. The macroinitiator has a M_n,GPC of 4700 g/mol and polydispersity index of 1.16 with the resulting copolymer having an experimentally determined M_n,GPC of 21,500 g/mol and polydispersity index of 1.60. The GPC traces indicated extremely high initiation efficiency with the resulting copolymer.

Biomass-derived furfuryl methacrylate has been successfully polymerized for the first time by anionic polymerization, leading to tactic or atactic polymers that exhibit sharply different thermal properties related to crosslinking and stable carbonaceous materials formation.

A new polymer blend comprised of a hydrogenated ring-opening polymer with an ester group as positive polymer and hydroxyl functionalized polystyrene as negative one produced the excellent transparent materials, which enabled a precise birefringence control in keeping with the other physical properties for optical film use. The excellent transparency even above those of T_g was attributed to a depressed phase separation that resulted from strong hydrogen bond between the ester and hydroxyl groups.

Electro-optic (EO) polycarbonates were prepared through copolymerization of the diol nonlinear optical chromophores and bisphenol A with bisphenol A bis(chloroformate) in solution. The obtained polycarbonates exhibited good film-forming properties and good thermal stability. The poled films of the resultant electro-optic polycarbonates revealed the maximum EO coefficient of 75 pm/V. Moreover, the obtained poled films also possessed better temporal stability. These good performances endow the resultant EO polycarbonates with device application in photonics.

Hydrophilic CO2-based biodegradable polycarbonates are designed and prepared. The resultant terpolymers are more hydrophlilic than PPC; water contact angles of the terpolymers with 4.2–23.6% of F_ME3MO were 68–25°. Furthermore, the terpolymers with >25.8% of F_ME3MO showed rapid and reversible thermo-responsive property in water, whose LCST ranged from 7 to 36.2 °C.

New photo-induced thiol-ene crosslinked films composed of linear methacrylate copolymer polythiols, exhibiting rapid cure, uniform network, and enhanced mechanical properties for surface coatings applications.

Thermoresponsive ABA triblock copolymers form flower-like micelles at room temperature and gels at higher temperatures and concentrations. Interestingly, this is influenced by the asymmetry of the triblocks; the more symmetric the architecture the lower the sol–gel temperature.

Well-defined resorcinarene-centered A₈B₄ miktoarm star copolymers were synthesized. These copolymers could self-assemble into spherical in aqueous solution with resorcinarene moieties on the hydrophilic/hydrophobic interface.

Block copolymer (P₁-X-P₂) are synthesized by radical addition cross-coupling reaction between two different polymeric radicals in-situ generated by two different bromopolymers (P₁-Br and P₂-Br) in the presence of ethyl dithiobenzoate or 1,1-diphenylethylene (X), which cannot be prepared by normal ATRC of mixture of P₁-Br and P₂-Br.

A new method using ring-opening polymerization and atom transfer radical polymerization that initiate a new disulfide-labeled double-head initiator for the synthesis of a variety of well-controlled polylactide-based block copolymers having disulfide linkages at block junctions.