Synthesis and characterization of ABA-type block copolymer of poly(trimethylene carbonate) with poly(ethylene glycol): Bioerodible copolymer

ABA-type block copolymers of poly(trimethylene carbonate) with poly(ethylene glycol) (M_n 6820), PTMC-b-PEG-b-PTMC, were synthesized by the ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) in the presence of poly-(ethylene glycol) with stannous octoate catalyst, and the copolymers with various compositions were obtained. The PTMC-b-PEG-b-PTMC copolymers were characterized with Fourier transform infrared and nuclear magnetic resonance spectroscopies. The intrinsic viscosities of resulting copolymers increased with the increase of 1,3-dioxan-2-one content in feed while the molar ratio of monomer over catalyst kept constant. It has been observed that the glass transition temperature (T_g) of the PTMC segments in copolymers, recorded from differential scanning calorimetry, was dependent on the composition of copolymers. The melting temperature (T_m) of PEG blocks in copolymer was lower than that of PEG polymer, and then disappeared as the length of PTMC blocks increased. The results of dynamic contact angle measurement clearly revealed that the hydrophilicity of resulting copolymers increased greatly with the increase of PEG content in copolymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 695–702, 1998     

Homopolymerization and copolymerization kinetics of trimethylene carbonate bearing a methoxyethoxy side group

The polymerization kinetics of 5‐[2‐{2‐(2‐methoxyethoxy)ethyoxy}‐ethoxymethyl]‐5‐methyl‐trimethylene carbonate (TMCM‐MOE3OM) synthesized using the organocatalyst 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) were studied and compared to those with the commonly used catalyst/initiator for ring‐opening polymerization of cyclic carbonates and esters, stannous 2‐ethylhexanoate. Further, the utility of each of these catalysts in the copolymerization of TMCM‐MOE3OM with trimethylene carbonate (TMC) and l ‐lactide (LLA) was examined. Regardless of conditions with either catalyst, homopolymerization of TMCM‐MOE3OM yielded oligomers, having number average molecular weight less than 4000 Da. The resultant molecular weight was limited by ring‐chain equilibrium as well as through monomer autopolymerization. Interestingly, autopolymerization of TMC was also achieved with DBU as the catalyst. Copolymerization with TMC using stannous 2‐ethylhexanoate as the catalyst yielded random copolymers, while diblock copolymers were formed by copolymerization with LLA. With DBU as the catalyst, copolymers with LLA could not be formed, while blocky copolymers were formed with TMC. These findings should be useful in the incorporation of this monomer in the design of polymer biomaterials. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 544–552     

Synthesis of a water‐soluble diblock copolymer of polysulfonic diphenyl aniline and poly(ethylene oxide)

We report the synthesis of a water‐soluble diblock copolymer composed of polysulfonic diphenyl aniline (PSDA) and poly(ethylene oxide) (PEO), which was prepared by reacting an amine‐terminated PSDA and tosylate PEO (PEO‐Tos). First, a HCl‐mediated polymerization of sulfonic diphenyl aniline monomer with the formation of HCl‐doped PSDA was carried out. After its neutralization and reduction, a secondary amine‐functionalized PSDA was obtained. Second, PEO‐Tos was synthesized via the tosylation of the monohydroxyl PEO methyl ether with tosylol chloride. Diblock copolymers with various PEO segment lengths (PSDA‐b‐PEO‐350 and PSDA‐b‐PEO‐2000) were obtained with PEO‐350 [number‐average molecular weight (M_n) = 350] and PEO‐2000 (M_n = 2000). The prepolymers and diblock copolymers were characterized by Fourier transform infrared spectroscopy, NMR, mass spectrometry, and ultraviolet–visible light. They had relatively low conductivities, ranging from 10^?6 to 10^?3 S/cm, because of the withdrawing effect of the sulfonic group as well as the steric effects of the bulky aromatic substitutuents at the N sites of the polyaniline backbone and of the PEO block. These polymers were self‐doped, and an intermolecular self‐doping was suggested. The external doping was, however, more effective. The self‐doping induced aggregation in water among the PSDA backbones, which was also stimulated by the presence of hydrophilic PEO blocks. Furthermore, the electrical conductivities of the diblock copolymers were strongly temperature‐dependent. PSDA‐b‐PEO‐2000 exhibited about one order of magnitude increase in conductivity upon heating from 32 to 57 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2179–2191, 2004     

Well‐defined poly[(dimethylamimo)ethyl methacrylate]‐b‐poly(fluoroalkyl methacrylate) diblock copolymers: Effects of different fluoroalkyl groups on the solution properties

A series of well‐defined, fluorinated diblock copolymers, poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,2‐trifluoroethyl methacrylate) (PDMA‐b‐PTFMA), poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,3,4,4,4‐hexafluorobutyl methacrylate) (PDMA‐b‐PHFMA), and poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(2,2,3,3,4,4,5,5‐octafluoropentyl methacrylate) (PDMA‐b‐POFMA), have been synthesized successfully via oxyanion‐initiated polymerization. Potassium benzyl alcoholate (BzO^?K⁺) was used to initiate DMA monomer to yield the first block PDMA. If not quenched, the first living chain could be subsequently used to initiate a feed F‐monomer (such as TFMA, HFMA, or OFMA) to produce diblock copolymers containing different poly(fluoroalkyl methacrylate) moieties. The composition and chemical structure of these fluorinated copolymers were confirmed by ¹H NMR, ¹⁹F NMR spectroscopy, and gel permeation chromatography (GPC) techniques. The solution behaviors of these copolymers containing (tri‐, hexa‐, or octa‐ F‐atom)FMA were investigated by the measurements of surface tension, dynamic light scattering (DLS), and UV spectrophotometer. The results indicate that these fluorinated copolymers possess relatively high surface activity, especially at neutral media. Moreover, the DLS and UV measurements showed that these fluorinated diblock copolymers possess distinct pH/temperature‐responsive properties, depending not only on the PDMA segment but also on the fluoroalkyl structure of the FMA units. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2702–2712, 2009     

Synthesis,characterization, effect of architecture on crystallization,and spherulitic growth of poly(L‐lactide)‐b‐poly(ethylene oxide) copolymers with different branch arms

Well‐defined poly(L ‐lactide)‐b‐poly(ethylene oxide) (PLLA‐b‐PEO) copolymers with different branch arms were synthesized via the controlled ring‐opening polymerization of L ‐lactide followed by a coupling reaction with carboxyl‐terminated poly(ethylene oxide) (PEO); these copolymers included both star‐shaped copolymers having four arms (4sPLLA‐b‐PEO) and six arms (6sPLLA‐b‐PEO) and linear analogues having one arm (LPLLA‐b‐PEO) and two arms (2LPLLA‐b‐PEO). The maximal melting point, cold‐crystallization temperature, and degree of crystallinity (X_c) of the poly(L ‐lactide) (PLLA) block within PLLA‐b‐PEO decreased as the branch arm number increased, whereas X_c of the PEO block within the copolymers inversely increased. This was mainly attributed to the relatively decreasing arm length ratio of PLLA to PEO, which resulted in various PLLA crystallization effects restricting the PEO block. These results indicated that both the PLLA and PEO blocks within the block copolymers mutually influenced each other, and the crystallization of both the PLLA and PEO blocks within the PLLA‐b‐PEO copolymers could be adjusted through both the branch arm number and the arm length of each block. Moreover, the spherulitic growth rate (G) decreased as the branch arm number increased: G_{6sPLLA‐b‐PEO} < G_{4sPLLA‐b‐PEO} < G_{2LPLLA‐b‐PEO} < G_{LPLLA‐b‐PEO}. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2034–2044, 2006     

Synthesis of four‐armed poly(ε‐caprolactone)‐block‐poly(ethylene oxide) by diethylzinc catalyst

Biodegradable, amphiphilic, four‐armed poly(?‐caprolactone)‐block‐poly(ethylene oxide) (PCL‐b‐PEO) copolymers were synthesized by ring‐opening polymerization of ethylene oxide in the presence of four‐armed poly(?‐caprolactone) (PCL) with terminal OH groups with diethylzinc (ZnEt₂) as a catalyst. The chemical structure of PCL‐b‐PEO copolymer was confirmed by ¹H NMR and ¹³C NMR. The hydroxyl end groups of the four‐armed PCL were successfully substituted by PEO blocks in the copolymer. The monomodal profile of molecular weight distribution by gel permeation chromatography provided further evidence for the four‐armed architecture of the copolymer. Physicochemical properties of the four‐armed block copolymers differed from their starting four‐armed PCL precursor. The melting points were between those of PCL precursor and linear poly(ethylene glycol). The length of the outer PEO blocks exhibited an obvious effect on the crystallizability of the block copolymer. The degree of swelling of the four‐armed block copolymer increased with PEO length and PEO content. The micelle formation of the four‐armed block copolymer was examined by a fluorescent probe technique, and the existence of the critical micelle concentration (cmc) confirmed the amphiphilic nature of the resulting copolymer. The cmc value increased with increasing PEO length. The absolute cmc values were higher than those for linear amphiphilic block copolymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 950–959, 2004     

Poly(trimethylene carbonate)/Poly(malic acid) Amphiphilic Diblock Copolymers as Biocompatible Nanoparticles

Amphiphilic polycarbonate–poly(hydroxyalkanoate) diblock copolymers, namely, poly(trimethylene carbonate) (PTMC)‐b‐poly(β‐malic acid) (PMLA), are reported for the first time. The synthetic strategy relies on commercially available catalysts and initiator. The controlled ring‐opening polymerization (ROP) of trimethylene carbonate (TMC) catalyzed by the organic guanidine base 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), associated with iPrOH as an initiator, provided iPrO?PTMC?OH, which served as a macroinitiator in the controlled ROP of benzyl β‐malolactonate (MLABe) catalyzed by the neodymium triflate salt (Nd(OTf)₃). The resulting hydrophobic iPrO?PTMC‐b‐PMLABe?OH copolymers were then hydrogenolyzed into the parent iPrO?PTMC‐b‐PMLA?OH copolymers. A range of well‐defined copolymers, featuring different sizes of segments (M_n,NMR up to 9300 g mol^?1; Ð_M=1.28–1.40), were thus isolated in gram quantities, as evidenced by NMR spectroscopy, size exclusion chromatography, thermogravimetric analysis, differential scanning calorimetry, and contact angle analyses. Subsequently, PTMC‐b‐PMLA copolymers with different hydrophilic weight fractions (11–75 %) self‐assembled in phosphate‐buffered saline upon nanoprecipitation into well‐defined nano‐objects with D_h=61–176 nm, a polydispersity index <0.25, and a negative surface charge, as characterized by dynamic light scattering and zeta‐potential analyses. In addition, these nanoparticles demonstrated no significant effect on cell viability at low concentrations, and a very low cytotoxicity at high concentrations only for PTMC‐b‐PMLA copolymers exhibiting hydrophilic fractions over 47 %, thus illustrating the potential of these copolymers as promising nanoparticles.     

Y‐shaped poly(ethylene glycol) and poly(trimethylene carbonate) amphiphilic copolymer: Synthesis and for drug delivery

New Y‐shaped (AB₂‐type) amphiphilic copolymers of poly(ethylene glycol) (PEG) with poly(trimethylene carbonate) (PTMC), PEG‐b‐(PTMC)₂, were successfully synthesized by the ring‐opening polymerization (ROP) of TMC with bishydroxy‐modified monomethoxy‐PEG (mPEG). First, a bishydroxy functional ROP initiator was synthesized by esterification of acryloyl bromide with mPEG, followed by Michael addition using excess diethanolamine. A series of Y‐shaped amphiphilic PEG‐(PTMC)₂ block copolymers were obtained via ROP of TMC using this PEG with bishydroxyl end groups as macroinitiator and ZnEt₂ as catalyst. The amphiphilic block copolymers with different compositions were characterized by gel permeation chromatography (GPC) and ¹H NMR, and their molecular weight was measured by GPC. The results showed that the molecular weight of Y‐shaped copolymers increased with the increase of the molar ratio of TMC to mPEG‐(OH)₂ initiator in feed while the PEG chain length was kept constant. The Y‐shaped copolymer mPEG‐(PTMC)₂ could self‐assemble into micelles in aqueous medium and the critical micelle concentration values of the micelles decrease with increase in hydrophobic PTMC block length of mPEG‐(PTMC)₂. The in vitro cytotoxicity and controlled drug release properties of the Y‐shaped amphiphilic block copolymers were also investigated. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 8131–8140, 2008     

Synthesis and characterization of poly[styrene‐b‐methyl(3,3,3‐trifluoropropyl)siloxane] diblock copolymers via anionic polymerization

A series of narrow molecular weight distribution (MWD) polystyrene‐b‐poly[methyl(3,3,3‐trifluoropropyl)siloxane] (PS‐b‐PMTFPS) diblock copolymers were synthesized by the sequential anionic polymerization of styrene and trans‐1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane in tetrahydrofuran (THF) with n‐butyllithium as the initiator. The diblock copolymers had narrow MWDs ranging from 1.06 to 1.20 and number‐average molecular weights ranging from 8.2 × 10³ to 37.1 × 10³. To investigate the properties of the copolymers, diblock copolymers with different weight fractions of poly[methyl(3,3,3‐trifluoropropyl)siloxane] (15.4–78.8 wt %) were prepared. The compositions of the diblock copolymers were calculated from the characteristic proton integrals of ¹H NMR spectra. For the anionic ring‐opening polymerization (ROP) of 1,3,5‐trimethyl‐1,3,5‐tris(3′,3′,3′‐trifluoropropyl)cyclotrisiloxane (F₃) initiated by polystyryllithium, high monomer concentrations could give high polymer yields and good control of MWDs when THF was used as the polymerization solvent. It was speculated that good control of the block copolymerization under the condition of high monomer concentrations was due to the slowdown of the anionic ROP rate of F₃ and the steric hindrance of the polystyrene precursors. There was enough time to terminate the ROP of F₃ when the polymer yield was high, and good control of block copolymerization could be achieved thereafter. The thermal properties (differential scanning calorimetry and thermogravimetric analysis) were also investigated for the PS‐b‐PMTFPS diblock copolymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4431–4438, 2005     

Synthesis of anionic amphiphilic diblock copolymers of poly(styrene) and poly(acrylic acid) by reverse iodine transfer polymerization (RITP) in solution and emulsion

Reverse iodine transfer polymerization (RITP), offering the appealing potential of the in situ generation of transfer agents out of molecular iodine I₂, is employed in the synthesis of anionic amphiphilic diblock copolymers of poly(styrene) and poly(acrylic acid). Starting with well‐characterized poly(styrene) as macro‐transfer agents synthesized by RITP, diblock copolymers poly(styrene)‐b‐poly(tert‐butyl acrylate) of various lengths are successfully yielded in solution with a good architectural control. These blocks are then subjected to acid deprotection and subsequent pH control to give rise to anionic amphiphilic poly(styrene)‐b‐poly(acrylic acid). Besides, homopolymers of tert‐butyl acrylate are produced by RITP both in solution and in emulsion. Furthermore, a fruitful trial of the synthesis of diblock copolymers poly(tert‐butyl acrylate)‐b‐poly(styrene) is carried out through chain extension of the poly(tert‐butyl acrylate) latex as a macro‐transfer agent in seeded emulsion polymerization of styrene. Finally, the prepared block copolymer is deprotected to bring about its amphiphilic nature and a pH control caters for its anionic character. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4389–4398     

Fluorinated block copolymers containing poly(vinylidene fluoride) or poly(vinylidene fluoride‐co‐hexafluoropropylene) blocks from perfluoropolyethers: Synthesis and thermal properties

PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers [where PFPE, PVDF, VDF, and HFP represent perfluoropolyether, poly(vinylidene fluoride), vinylidene fluoride (or 1,1‐difluoroethylene), and hexafluoropropylene] were synthesized by radical (co)telomerizations of VDF (or VDF and HFP) with an iodine‐terminated perfluoropolyether (PFPE‐I). Di‐tert‐butyl peroxide (DTBP) was used and was shown to act as an efficient thermal initiator. The numbers of VDF and VDF/HFP base units in the block copolymers were assessed with ¹⁹F NMR spectroscopy. According to the initial [PFPE‐I]₀/[fluoroalkenes]₀ and [DTBP]₀/[fluoroalkenes]₀ molar ratios, fluorinated block copolymers of various molecular weights (1500–30,300) were obtained. The states and thermal properties of these fluorocopolymers were investigated. The compounds containing PVDF blocks with more than 30 VDF units were crystalline, whereas all those containing poly(VDF‐co‐HFP) blocks exhibited amorphous states, whatever the numbers were of the fluorinated base units. All the samples showed negative glass‐transition temperatures higher than that of the starting PFPE. Interestingly, these PFPE‐b‐PVDF and PFPE‐b‐poly(VDF‐co‐HFP) block copolymers exhibited good thermostability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 160–171, 2003     

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     

Synthesis and characterization of novel poly(ester carbonate)s based on pentaerythritol

Novel poly(ester carbonate)s were synthesized by the ring‐opening polymerization of L ‐lactide and functionalized carbonate monomer 9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one derived from pentaerythritol with diethyl zinc as an initiator. ¹H NMR analysis revealed that the carbonate content in the copolymer was almost equal to that in the feed. DSC results indicated that T_g of the copolymer increased with increasing carbonate content in the copolymer. Moreover, the protecting benzylidene groups in the copolymer poly(L ‐lactide‐co‐9‐phenyl‐2,4,8,10‐tetraoxaspiro[5,5]undecan‐3‐one) were removed by hydrogenation with palladium hydroxide on activated charcoal as a catalyst to give a functional copolymer, poly(L ‐lactide‐co‐2,2‐dihydroxylmethyl‐propylene carbonate), containing pendant primary hydroxyl groups. Complete deprotection was confirmed by ¹H NMR and FTIR spectroscopy. The in vitro degradation rate of the deprotected copolymers was faster than that of the protected copolymers in the presence of proteinase K. The cell morphology and viability on a copolymer film evaluated with ECV‐304 cells showed that poly(ester carbonate)s derived from pentaerythritol are good biocompatible materials suitable for biomedical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45:1737 –1745, 2007     

Luminescent polymeric ruthenium complexes with polystyrene‐b‐poly(methyl methacrylate) macroligands: The sequential activation of initiator sites for blocks generated by parallel polymerization mechanisms

The synthesis of polystyrene‐b‐poly(methyl methacrylate) diblock copolymers with a luminescent ruthenium(II) tris(bipyridine) [Ru(bpy)₃] complex at the block junction is described. The macroligand precursor, polystyrene bipyridine‐poly(methyl methacrylate) [bpy(PS–H)(PMMA)], was synthesized via the atom transfer radical polymerization of styrene and methyl methacrylate from two independent, sequentially activated initiating sites. Both polymerization steps resulted in the growth of blocks with sizes consistent with monomer loading and narrow molecular weight distributions (i.e., polydispersity index < 1.3). Subsequent reactions with ruthenium(II) bis(bipyridine) dichloride [Ru(bpy)₂Cl₂] in the presence of Ag⁺ generated the ruthenium tris(bipyridine)‐centered diblock, which is of interest for the imaging of block copolymer microstructures and for incorporation into new photonic materials. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4250–4255, 2002     

Synthesis of ABA‐triblock and star‐diblock copolymers with poly(2‐adamantyl vinyl ether) and poly(n‐butyl vinyl ether) segments: New thermoplastic elastomers composed solely of poly(vinyl ether) backbones

ABA‐type triblock copolymers and AB‐type star diblock copolymers with poly(2‐adamantyl vinyl ether) [poly(2‐AdVE)] hard outer segments and poly(n‐butyl vinyl ether) [poly(NBVE)] soft inner segments were synthesized by sequential living cationic copolymerization. Although both the two polymer segments were composed solely of poly(vinyl ether) backbones and hydrocarbon side chains, they were segregated into microphase‐separated structure, so that the block copolymers formed thermoplastic elastomers. Both the ABA‐type triblock copolymers and the AB‐type star diblock copolymers exhibited rubber elasticity over wide temperature range. For example, the ABA‐type triblock copolymers showed rubber elasticity from about ?53 °C to about 165 °C and the AB‐type star diblock copolymer did from about ?47 °C to 183 °C with a similar composition of poly(2‐AdVE) and poly(NBVE) segments in the dynamic mechanical analysis. The AB‐type star diblock copolymers exhibited higher tensile strength and elongation at break than the ABA‐type triblock copolymers. The thermal decomposition temperatures of both the block copolymers were as high as 321–331 °C, indicating their high thermal stability. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Bifunctional imidodiphosphoric acid‐catalyzed controlled/living ring‐opening polymerization of trimethylene carbonate resulting block, α,ω‐dihydroxy telechelic,and star‐shaped polycarbonates

The ring‐opening polymerization (ROP) of trimethylene carbonate (TMC) using imidodiphosphoric acid (IDPA) as the organocatalyst and benzyl alcohol (BnOH) as the initiator has been investigated. The polymerization proceeded without decarboxylation to afford poly(trimethylene carbonate) (PTMiC) with controlled molecular weight and narrow polydispersity. ¹H NMR, SEC, and MALDI‐TOF MS measurements of the obtained PTMC clearly indicated the quantitative incorporation of the initiator at the chain end. The controlled/living nature for the IDPA‐catalyzed ROP of TMC was confirmed by the kinetic and chain extension experiments. A bifunctional activation mechanism was proposed for IDPA catalysis based on NMR and FTIR studies. Additionally, 1,3‐propanediol, 1,1,1‐trimethylolpropane, and pentaerythritol were used as di‐ol, tri‐, and tetra‐ol initiators, producing the telechelic or star‐shaped polycarbonates with narrow polydispersity indices. The well‐defined diblock copolymers, poly(trimethylene carbonate)‐block‐poly(δ‐valerolactone) and poly(trimethylene carbonate)‐block‐poly(ε‐caprolactone), have been successfully synthesized by using the IDPA catalysis system. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1009–1019     

Synthesis of amphiphilic poly(methyl methacrylate‐ b‐ethylene oxide) copolymers from monohydroxy telechelic poly(methyl methacrylate) as macroinitiator

The synthesis of well‐defined poly(methyl methacrylate)‐block‐poly(ethylene oxide) (PMMA‐b‐PEO) dibock copolymer through anionic polymerization using monohydroxy telechelic PMMA as macroinitiator is described. Living anionic polymerization of methyl methacrylate was performed using initiators derived from the adduct of diphenylethylene and a suitable alkyllithium, either of which contains a hydroxyl group protected with tert‐butyldimethylsilyl moiety in tetrahydrofuran (THF) at ?78 °C in the presence of LiClO₄. The synthesized telechelic PMMAs had good control of molecular weight with narrow molecular weight distribution (MWD). The ¹H NMR and MALDI‐TOF MS analysis confirmed quantitative functionalization of chain‐ends. Block copolymerization of ethylene oxide was carried out using the terminal hydroxyl group of PMMA as initiator in the presence of potassium counter ion in THF at 35 °C. The PMMA‐b‐PEO diblock copolymers had moderate control of molecular weight with narrow MWD. The ¹H NMR results confirm the absence of trans‐esterification reaction of propagating PEO anions onto the ester pendants of PMMA. The micellation behavior of PMMA‐b‐PEO diblock copolymer was examined in water using ¹H NMR and dynamic light scattering. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2132–2144, 2008     

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     

Synthesis and characterization of well‐defined diblock and triblock copolymers of poly(N‐isopropylacrylamide) and poly(ethylene oxide)

Well‐defined diblock and triblock copolymers composed of poly(N‐isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) (PEO) were successfully synthesized through the reversible addition–fragmentation chain transfer polymerization of N‐isopropylacrylamide (NIPAM) with PEO capped with one or two dithiobenzoyl groups as a macrotransfer agent. ¹H NMR, Fourier transform infrared, and gel permeation chromatography instruments were used to characterize the block copolymers obtained. The results showed that the diblock and triblock copolymers had well‐defined structures and narrow molecular weight distributions (weight‐average molecular weight/number‐average molecular weight < 1.2), and the molecular weight of the PNIPAM block in the diblock and triblock copolymers could be controlled by the initial molar ratio of NIPAM to dithiobenzoate‐terminated PEO and the NIPAM conversion. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4873–4881, 2004     

Synthesis and Characterization of New Block Copolymers with Poly(ethylene oxide) and Poly[3(S)‐sec‐butylmorpholine‐2,5‐dione] Sequences

Four different types of polydepsipeptide‐polyether block copolymers were synthesized via ring‐opening polymerization of 3(S)‐sec‐butylmorpholine‐2,5‐dione (BMD) in the presence of hydroxytelechelic poly(ethylene oxide) (PEO) with stannous octoate as a catalyst.The polymers were an AB block copolymer, an ABA block copolymer, an (A)₂B star shaped copolymer and an (A)₂B(A)₂ copolymer, where A is a poly[3(S)‐sec‐butylmorpholine‐2,5‐dione] (PBMD) and B a poly(ethylene oxide) block. The molar ratio of BMD to PEO was varied to obtain copolymers with different weight fractions of PBMD blocks ranging from 59.8 to 96.7 wt.‐%. The crystallinity of the PEO phase in the copolymers decreases in the following order: AB > (A)₂B > ABA > (A)₂B(A)₂ . The static contact angle θ decreases with increasing PEO content in the block copolymers.