MOLECULAR AND SUPRAMOLECULAR ORDERING IN CONFINED ENVIRONMENTS

Crystal and phase morphologies and structures determined by self-organization of crystalline-amorphous diblockcopolymers, crystallization of the crystallizable blocks, and vitrification of the amorphous blocks are reviewed through asystematic study on a series of poly(ethylene oxide)-b-polystyrene (PEO-b-PS) diblock copolymers. On the base ofcompetitions among these three processes, molecular and supramolecular ordering in confined environments can beinvestigated. In a concentration-fluctuation-induced disordered (D_(CF)) diblock copolymer, the competition between crystalli-zation of the PEO blocks and vitrification of the PS blocks is momtored by time-resolved simultaneous small angle X-rayscattering (SAXS) and wide angle X-ray diffraction (WAXD) techniques. In the case of T_c相似文献   

Synthesis and Characterization of Triblock Terpolymers with three Potentially Crystallisable Blocks: Polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone)

A first attempt was made to produce novel ABC triblock terpolymers with three potentially crystallisable blocks: polyethylene (PE), poly(ethylene oxide) (PEO), and poly(ε-caprolactone) (PCL). Polybutadiene-b-poly(ethylene oxide) diblock copolymers were synthesized by living anionic polymerization. Then, a non-catalyzed thermal polymerization of ε-caprolactone from the hydroxyl end group of the PB-b-PEO diblock precursors was performed. Finally, hydrogenation by Wilkinson catalyst produced PE-b-PEO-b-PCL triblock terpolymers. Side reactions were detected that lead to the formation of undesired PCL-b-PEO diblock copolymers, however, these impurities were successfully removed by purification. A range of triblock terpolymers with PCL and PEO minor components were prepared. Topological restrictions on the PEO middle block prevented this block from crystallizing while the complex crystallization behavior of the PE and PCL blocks was documented by DSC and WAXS measurements.     

Crystallization and morphology of poly(ethylene oxide‐b‐lactide) crystalline–crystalline diblock copolymers

The crystallization behaviors and morphology of asymmetric crystalline–crystalline diblock copolymers poly(ethylene oxide‐lactide) (PEO‐b‐PLLA) were investigated using differential scanning calorimetry (DSC), wide angle X‐ray diffraction (WAXD), and microscopic techniques (polarized optical microscopy (POM) and atomic force microscopy (AFM)). Both blocks of PEO₅‐b‐PLLA₁₆ can be crystallized, which was confirmed by WAXD, while PEO block in PEO₅‐b‐PLLA₃₀ is difficult to crystallize because of the confinement induced by the high glass transition temperature and crystallization of PLLA block with the microphase separation of the block copolymer. Comparing with the crystallization and morphology of PLLA homopolymer and differences between the two copolymers, we studied the influence of PEO block and microphase separation on the crystallization and morphology of PLLA block. The boundary temperature (T_b) was observed, which distinguishes the crystallization into high‐ and low‐temperature ranges, the growth rate and morphology were quite different between the ranges. Crystalline morphologies including banded spherulite, dendritic crystal, and dense branching in PEO₅‐b‐PLLA₁₆ copolymer were formed. The typical morphology of dendritic crystals including two different sectors were observed in PEO₅‐b‐PLLA₃₀ copolymer, which can be explained by secondary nucleation, chain growth direction, and phase separation between the two blocks during the crystallization process. Lozenge‐shaped crystals of PLLA with screw dislocation were also observed employing AFM, but the crystalline morphology of PEO block was not observed using microscopy techniques because of its small size. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1400–1411, 2008     

Synthesis,characterization, and properties of amphiphilic chitosan copolymers with mixed side chains by click chemistry

Novel amphiphilic chitosan copolymers with mixed side chains of poly(ε‐caprolactone) and poly(ethylene oxide) (CS‐g‐PCL/PEO) were successfully synthesized by “graft to” approach via click chemistry. The melting and crystallization behaviors and crystalline morphology of CS‐g‐PCL/PEO copolymers can be adjusted by the alteration of the feed ratio of PCL and PEO segments. CS‐g‐PCL/PEO copolymers revealed crystalline morphology different from that of linear alkynyl PCL and alkynyl PEO due to the influence of brush structure of copolymers and the mutual influence of PCL and PEO segments. The hydrophilicity of the CS copolymers can be improved and adjusted by the alteration of the composition of PCL and PEO segments. Moreover, the CS copolymers can self‐assemble into spherical micelles in aqueous solution. Investigation shows that the size of the CS copolymer micelles increased with the increase of the content of hydrophobic PCL segments in copolymers, which indicated that the micellar behavior of the copolymers can be controlled by the adjustment of the ratio of PCL and PEO segments in copolymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3476–3486, 2010     

Direct Assembly of Mesoporous Silica Functionalized with Polypeptides for Efficient Dye Adsorption

Herein, we introduce a new polypeptide‐functionalized mesoporous silica template fabricated from a biodegradable poly(ethylene oxide‐b‐?‐caprolactone) (PEO‐b‐PCL) diblock copolymer and a poly(tyrosine) (PTyr) biopolymer. The crystallization behavior of the PEO‐b‐PCL diblock copolymer changes after blending, but the secondary structure of PTry remains stable. After selective solvent extraction in THF, the PEO‐b‐PCL is removed, but PTyr remains within the silica matrix due to its different solubility. Fourier‐transform IR spectroscopic analysis (FTIR), thermal gravitometry analysis (TGA), small‐angle X‐ray scattering (SAXS), and X‐ray diffraction (XRD) studies confirm the retention of PTyr to form a polypeptide‐functionalized mesoporous material. The adsorption of methylene blue hydrate (MB) from aqueous solution into the polypeptide‐functionalized mesoporous silica is investigated, thus revealing that the nanocomposite exhibits a high adsorption capacity relative to pure silica due to hydrogen‐bonding interactions between the hydroxy phenolic group of PTyr and the N‐containing aromatic ring from MB.     

Norbornene‐functionalized PEO‐b‐PCL: A versatile platform for mikto‐arm star,umbrella‐like,and comb‐like graft copolymers

Well‐defined in‐chain norbornene‐functionalized poly(ethylene oxide)‐b‐poly(?‐caprolactone) copolymers (NB‐PEO‐b‐PCL) were synthesized from a dual clickable containing both hydroxyl‐ and alkyne‐reactive groups, namely heterofunctional norbornene 3‐exo‐(2‐exo‐(hydroxymethyl)norborn‐5‐enyl)methyl hexynoate. A range of NB‐PEO‐b‐PCL copolymers were obtained using a combination of orthogonal organocatalyzed ring‐opening polymerization (ROP) and click copper‐catalyzed azide–alkyne cycloaddition (CuAAC). Ring‐opening metathesis polymerization (ROMP) of NB‐PEO‐b‐PCL macromonomers using ruthenium‐based Grubbs’ catalysts provides comb‐like and umbrella‐like graft copolymers bearing both PEO and PCL grafts on each monomer unit. Mikto‐arm star A₂B₂ copolymers were obtained through a new strategy based on thiol–norbornene photoinitiated click chemistry between 1,3‐propanedithiol and NB‐PEO‐b‐PCL. The results demonstrate that in‐chain NB‐PEO‐b‐PCL copolymers can be used as a platform to prepare mikto‐arm star, umbrella‐, and comb‐like graft copolymers. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 4051–4061     

Amphiphilic biodegradable poly(CL-b-PEG-b-CL) triblock copolymers prepared by novel rare earth complex: Synthesis and crystallization properties

Amphiphilic biodegradable poly(CL-b-PEG-b-CL) triblock copolymers have been successfully prepared by the ring-opening polymerization of ε-caprolactone (CL) employing yttrium tris(2,6-di-tert-butyl-4-methylphenolate) [Y(DBMP)₃] as catalyst and double-hydroxyl capped PEGs (DHPEG) as macro-initiator. The triblock architecture, molecular weight, thermal and crystallization properties of the copolymers were characterized by NMR spectra, SEC, DSC and WAXD analyses. The isothermal crystallization behavior of the copolymers was investigated by POM analysis in detail, which is greatly influenced by the length of PCL and PEG blocks. On the POM micrograph of PEG_10,000-(PCL₈₆₀₀)₂, a unique morphology of concentric spherulites was observed due to the sequent crystallization of the PCL and PEG blocks.     

Novel synthesis of biodegradable amphiphilic linear and star block copolymers based on poly(ε‐caprolactone) and poly(ethylene glycol)

Biodegradable, amphiphilic, diblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol) (PCL‐b‐PEG), triblock poly(ε‐caprolactone)‐block‐poly(ethylene glycol)‐block‐poly(ε‐caprolactone) (PCL‐b‐PEG‐b‐PCL), and star shaped copolymers were synthesized by ring opening polymerization of ε‐caprolactone in the presence of poly(ethylene glycol) methyl ether or poly(ethylene glycol) or star poly(ethylene glycol) and potassium hexamethyldisilazide as a catalyst. Polymerizations were carried out in toluene at room temperature to yield monomodal polymers of controlled molecular weight. The chemical structure of the copolymers was investigated by ¹H and ¹³C NMR. The formation of block copolymers was confirmed by ¹³C NMR and DSC investigations. The effects of copolymer composition and molecular structure on the physical properties were investigated by GPC and DSC. For the same PCL chain length, the materials obtained in the case of linear copolymers are viscous whereas in the case of star copolymer solid materials are obtained with low T_g and T_m temperatures. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3975–3985, 2007     

Synthesis and Characterization of Star‐Shaped Diblock Poly(ε‐caprolactone)/Poly(ethylene oxide) Copolymers

Summary: Star‐shaped hydroxy‐terminated poly(ε‐caprolactone)s (ssPCL), with arms of different lengths, were obtained by ring‐opening polymerization (ROP) of ε‐caprolactone initiated by pentaerythritol, and were condensed with α‐methyl‐ω‐(3‐carboxypropionyloxy)‐poly(ethylene oxide)s ( = 550–5 000) to afford four‐armed PCL‐PEO star diblock copolymers (ssPCL‐PEO). The polymers were characterized by ¹H and ¹³C NMR spectroscopy and size‐exclusion chromatography (SEC). The melting behavior of ssPCLs was studied by differential scanning calorimetry (DSC). X‐ray diffraction and DSC techniques were used to investigate the crystalline phases of ssPCL‐PEOs.

The part of the synthesis of four‐armed star‐shaped diblock poly(ε‐caprolactone)‐poly(ethylene oxide) copolymers as described.     

Complex,degradable polyester materials via ketoxime ether‐based functionalization: Amphiphilic,multifunctional graft copolymers and their resulting solution‐state aggregates

Degradable, amphiphilic graft copolymers of poly(ε‐caprolactone)‐graft‐poly(ethylene oxide), PCL‐g‐PEO, were synthesized via a grafting onto strategy taking advantage of the ketones presented along the backbone of the statistical copolymer poly(ε‐caprolactone)‐co‐(2‐oxepane‐1,5‐dione), (PCL‐co‐OPD). Through the formation of stable ketoxime ether linkages, 3 kDa PEO grafts and p‐methoxybenzyl side chains were incorporated onto the polyester backbone with a high degree of fidelity and efficiency, as verified by NMR spectroscopies and GPC analysis (90% grafting efficiency in some cases). The resulting block graft copolymers displayed significant thermal differences, specifically a depression in the observed melting transition temperature, T_m, in comparison with the parent PCL and PEO polymers. These amphiphilic block graft copolymers undergo self‐assembly in aqueous solution with the P(CL‐co‐OPD‐co‐(OPD‐g‐PEO)) polymer forming spherical micelles and a P(CL‐co‐OPD‐co‐(OPD‐g‐PEO)‐co‐(OPD‐g‐pMeOBn)) forming cylindrical or rod‐like micelles, as observed by transmission electron microscopy and atomic force microscopy. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3553–3563, 2010     

Well‐defined polyolefin/poly(ε‐caprolactone) diblock copolymers: New synthetic strategy and application

A new synthetic strategy, the combination of living polymerization of ylides and ring‐opening polymerization (ROP), was successfully used to obtain well‐defined polymethylene‐b‐poly(ε‐caprolactone) (PM‐b‐PCL) diblock copolymers. Two hydroxyl‐terminated polymethylenes (PM‐OH, M_n= 1800 g mol^?1 (PDI = 1.18) and M_n = 6400 g mol^?1 (PDI = 1.14)) were prepared using living polymerization of dimethylsulfoxonium methylides. Then, such polymers were successfully transformed to PM‐b‐PCL diblock copolymers by using stannous octoate as a catalyst for ROP of ε‐caprolactone. The GPC traces and ¹H NMR of PM‐b‐PCL diblock copolymers indicated the successful extension of PCL segment (M_n of PM‐b‐PCL = 5200–10,300 g mol^?1; PDI = 1.06–1.13). The thermal properties of the double crystalline diblock copolymers were investigated by differential scanning calorimetry (DSC). The results indicated that the incorporation of crystalline segments of PCL chain effectively influence the crystalline process of PM segments. The low‐density polyethylene (LDPE)/PCL and LDPE/polycarbonate (PC) blends were prepared using PM‐b‐PCL as compatibilizer, respectively. The scanning electron microscopy (SEM) observation on the cryofractured surface of such blend polymers indicates that the PM‐b‐PCL diblock copolymers are effective compatibilizers for LDPE/PCL and LDPE/PC blends. Porous films were fabricated via the breath‐figure method using different concentration of PM‐b‐PCL diblock copolymers in CH₂Cl₂ under a static humid condition. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Tailoring block copolymer morphologies via alkyne/azide cycloaddition

We investigated the morphological transitions induced by alkyne/azide Huisgen 1,3‐dipolar cycloaddition reaction in a series of poly(ethylene oxide)‐block‐poly(n‐butyl methacrylate‐random‐propargyl methacrylate) (PEO‐b‐P(nBMA‐r‐PgMA)) diblock copolymers. Studies on the phase behavior of neat diblock copolymers revealed that the interactions between the PEO block and the terminal alkyne groups in the P(nBMA‐r‐PgMA) block significantly affected the miscibility between the two blocks and the crystallization of the PEO block. Phase‐mixed diblock copolymers underwent disorder‐to‐order transitions by blending with Rhodamine B azide and annealing at elevated temperatures. Different morphologies were achieved, not only by controlling the composition of the block copolymer but also by blending the diblock copolymer with different amount of azides. Microphase separated PEO‐b‐P(nBMA‐r‐PgMA) diblock copolymer also exhibited reactivity toward azides, and order‐to‐order transitions were observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

A novel and versatile potassium‐based catalyst for the ring opening polymerization of cyclic esters

Poly(lactide) (PLA), poly(ε‐caprolactone) (PCL) and poly(trimethylene carbonate) (PTMC) homopolymers of high molecular weight were prepared using potassium‐based catalyst. Polymerizations were carried out in toluene at room temperature. The chemical structure of the polymers was investigated by ¹H and ¹³C NMR. The physical properties investigated by GPC and DSC for the polymers obtained are similar to those prepared using tin octanoate based catalyst. Using a sequential polymerization procedure, PLA‐b‐PCL, PLA‐b‐PTMC, and PCL‐b‐PTMC diblock copolymers were synthesized and characterized in terms of their composition and physical properties. The formation of diblock copolymers was confirmed by NMR and DSC measurements. In vitro cytotoxicity tests have been carried out using MTS assay and the results show the biocompatibility of these polymers in the presence of the fibroblast cells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5348–5362, 2008     

Melt crystallization and morphology of poly(ε‐caprolactone)‐poly(ethylene glycol) diblock copolymers with different compositions and molecular weights

Ring opening polymerization of ε‐caprolactone was realized in the presence of monomethoxy poly(ethylene glycol) with M_n = 1000 and 2000, using Zn(La)₂ as catalyst. The resulting PCL‐PEG diblock copolymers with CL/EO repeat unit molar ratios from 0.2 to 3.0 were characterized by using DSC, WAXD, SEC, and ¹H NMR. The crystal phase of PCL blocks exist in all polymers, and the crystallization ability of PCL blocks increases with CL/EO ratio. PEG blocks are able to crystallize for copolymers with CL/EO below 1.0 only. Melt crystallization results were analyzed with Avrami equation. The Averami exponent n is around 3.0 in most cases, in agreement with heterogeneous nucleation with three dimensional growth. The morphology of the crystals was observed by using POM. Rod‐like crystals were found to grow in 1, 3 or 2, 4 quadrants for samples with low molecular weights. In the case of a copolymer with M_n,PEG = 2000 and M_n,PCL = 800, PEG blocks could crystallize and grow on PCL crystals after PCL finished to form rod‐like crystals, leading to formation of poorly or well structured spherulites. The spherulite growth rate (G) was determined at different crystallization temperatures (T_c) ranging from 9 to 49 °C. All the copolymers present a steady G decrease with increasing crystallization temperature due to lower undercooling. On the other hand, increase of CL/EO ratio leads to increase of G in the same T_c range. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 286–293, 2010     

Hydrophilic–hydrophobic AB diblock copolymers containing poly(trimethylene carbonate) and poly(ethylene oxide) blocks

AB‐type block copolymers with poly(trimethylene carbonate) [poly(TMC); A] and poly(ethylene oxide) [PEO; B; number‐average molecular weight (M_n) = 5000] blocks [poly(TMC)‐b‐PEO] were synthesized via the ring‐opening polymerization of trimethylene carbonate (TMC) in the presence of monohydroxy PEO with stannous octoate as a catalyst. M_n of the resulting copolymers increased with increasing TMC content in the feed at a constant molar ratio of the monomer to the catalyst (monomer/catalyst = 125). The thermal properties of the AB diblock copolymers were investigated with differential scanning calorimetry. The melting temperature of the PEO blocks was lower than that of the homopolymer, and the crystallinity of the PEO block decreased as the length of the poly(TMC) blocks increased. The glass‐transition temperature of the poly(TMC) blocks was dependent on the diblock copolymer composition upon first heating. The static contact angle decreased sharply with increasing PEO content in the diblock copolymers. Compared with poly(TMC), poly(TMC)‐b‐PEO had a higher Young's modulus and lower elongation at break. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4819–4827, 2005     

Synthesis and characterization of side‐chain liquid crystalline ABC triblock copolymers with p‐methoxyazobenzene moieties by atom transfer radical polymerization

A series of novel side‐chain liquid crystalline ABC triblock copolymers composed of poly(ethylene oxide) (PEO), polystyrene (PS), and poly[6‐(4‐methoxy‐4′‐oxy‐azobenzene) hexyl methacrylate] (PMMAZO) were synthesized by atom transfer radical polymerization (ATRP) using CuBr/1,1,4,7,7‐pentamethyldiethylenetriamine (PMDETA) as a catalyst system. First, the bromine‐terminated diblock copolymer poly(ethylene oxide)‐block‐polystyrene (PEO‐PS‐Br) was prepared by the ATRP of styrene initiated with the macro‐initiator PEO‐Br, which was obtained from the esterification of PEO and 2‐bromo‐2‐methylpropionyl bromide. An azobenzene‐containing block of PMMAZO with different molecular weights was then introduced into the diblock copolymer by a second ATRP to synthesize the novel side‐chain liquid crystalline ABC triblock copolymer poly(ethylene oxide)‐block‐polystyrene‐block‐poly[6‐(4‐methoxy‐4′‐oxy‐azobenzene) hexyl methacrylate] (PEO‐PS‐PMMAZO). These block copolymers were characterized using proton nuclear magnetic resonance (¹H NMR) and gel permeation chromatograph (GPC). Their thermotropic phase behaviors were investigated using differential scanning calorimetry (DSC) and polarized optical microscope (POM). These triblock copolymers exhibited a smectic phase and a nematic phase over a relatively wide temperature range. At the same time, the photoresponsive properties of these triblock copolymers in chloroform solution were preliminarily studied. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4442–4450, 2008     

Supramolecular polyseudorotaxanes formation between star‐block copolymer and α‐cyclodextrin: From outer block to diblock inclusion complexation

A series of star‐block poly(L ‐lactide)‐b‐poly(ethylene oxide) (SPLLA‐b‐PEO) copolymers were synthesized by ring‐opening polymerization (ROP) and DCC chemistry. The inclusion complexes of SPLLA‐b‐PEO copolymers and α‐cyclodextrin (α‐CD) were prepared with two different methods. FTIR, ¹H NMR, WAXD, DSC, and TGA indicate that α‐CD only can be threaded onto PEO blocks in inclusion complexes of α‐CD‐SPLLA‐b‐PEO1.1K‐a, α‐CD‐SPLLA‐b‐PEO2K‐a, and α‐CD‐SPLLA‐b‐PEO5K‐a formed without heating and ultrasonication, and can be threaded onto both PLLA and PEO blocks in inclusion complexes of α‐CD‐SPLLA‐b‐PEO1.1K‐b, α‐CD‐SPLLA‐b‐PEO2K‐b, and α‐CD‐SPLLA‐b‐PEO5K‐b formed with heating and ultrasonication. Namely, α‐CDs can be threaded onto PEO blocks and the flanking bulky PLLA blocks of star‐block copolymers to form stable polyseudorotaxanes with heating method and ultrasonication to conquer the activation energy barrier of the inclusion complexation between bulky PLLA and α‐CD and the effect of the steric hindrance of star‐block copolymers. With the alteration of preparing methods, the inclusion complexes of α‐CD with the outer PEO block or PEO and PLLA blocks were obtained successfully. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2754–2762, 2009     

Synthesis,reactivity, and optoelectronic properties of poly(3‐alkenylthiophene) diblock copolymers

Poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) and poly(3‐hexylthiophene)‐b‐poly(3‐undecenylthiophene) diblock copolymers have been synthesized by McCullough method. X‐ray diffraction analysis of the diblock copolymers displayed all the reflection peaks specific to regioregular poly(3‐hexylthiophene), indicating that the presence of poly(3‐alkenylthiophene) block does not affect the packing of the polymer in the solid state. The synthesized diblock copolymers were subjected to hydroboration/oxidation and hydrosilation to demonstrate the reactivity of the alkenyl substituents. Furthermore, poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene) was used as a chain transfer agent for the ruthenium‐catalyzed ring‐opening metathesis polymerization of cyclooctene to generate a polycyclooctene graft copolymer, which was hydrogenated to give poly(3‐hexylthiophene)‐b‐poly(3‐pentenylthiophene‐g‐polyethylene). The opto‐electronic properties and the morphology of the synthesized polymers have been investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Hydrophilic segmented block copolymers based on poly(ethylene oxide) and monodisperse amide segments

Segmented block copolymers based on poly(ethylene oxide) (PEO) flexible segments and monodisperse crystallizable bisester tetra‐amide segments were made via a polycondensation reaction. The molecular weight of the PEO segments varied from 600 to 4600 g/mol and a bisester tetra‐amide segment (T6T6T) based on dimethyl terephthalate (T) and hexamethylenediamine (6) was used. The resulting copolymers were melt‐processable and transparent. The crystallinity of the copolymers was investigated by differential scanning calorimetry (DSC) and Fourier Transform infrared (FTIR). The thermal properties were studied by DSC, temperature modulated synchrotron small angle X‐ray scattering (SAXS), and dynamic mechanical analysis (DMA). The elastic properties were evaluated by compression set (CS) test. The crystallinity of the T6T6T segments in the copolymers was high (>84%) and the crystallization fast due to the use of monodisperse tetra‐amide segments. DMA experiments showed that the materials had a low T_g, a broad and almost temperature independent rubbery plateau and a sharp flow temperature. With increasing PEO length both the PEO melting temperature and the PEO crystallinity increased. When the PEO segment length was longer than 2000 g/mol the PEO melting temperature was above room temperature and this resulted in a higher modulus and in higher compression set values at room temperature. The properties of PEO‐T6T6T copolymers were compared with similar poly(propylene oxide) and poly(tetramethylene oxide) copolymers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 4522–4535, 2007     

Synthesis and characterization of well‐defined ABC 3‐Miktoarm star‐shaped terpolymers based on poly(styrene), poly(ethylene oxide), and poly(ϵ‐caprolactone) by combination of the “living” anionic polymerization with the ring‐opening polymerization

A series of well‐defined ABC 3‐Miktoarm star‐shaped terpolymers [Poly(styrene)‐Poly(ethylene oxide)‐Poly(ε‐caprolactone)](PS‐PEO‐PCL) with different molecular weight was synthesized by combination of the “living” anionic polymerization with the ring‐opening polymerization (ROP) using macro‐initiator strategy. Firstly, the “living” poly(styryl)lithium (PS^?Li⁺) species were capped by 1‐ethoxyethyl glycidyl ether(EEGE) quantitatively and the PS‐EEGE with an active and an ethoxyethyl‐protected hydroxyl group at the same end was obtained. Then, using PS‐EEGE and diphenylmethylpotassium (DPMK) as coinitiator, the diblock copolymers of (PS‐b‐PEO)_p with the ethoxyethyl‐protected hydroxyl group at the junction point were achieved by the ROP of EO and the subsequent termination with bromoethane. The diblock copolymers of (PS‐b‐PEO)_d with the active hydroxyl group at the junction point were recovered via the cleavage of ethoxyethyl group on (PS‐b‐PEO)_p by acidolysis and saponification successively. Finally, the copolymers (PS‐b‐PEO)_d served as the macro‐initiator for ROP of ε‐CL in the presence of tin(II)‐bis(2‐ethylhexanoate)(Sn(Oct)₂) and the star(PS‐PEO‐PCL) terpolymers were obtained. The target terpolymers and the intermediates were well characterized by ¹H‐NMR, MALDI‐TOF MS, FTIR, and SEC. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1136–1150, 2008