Synthesis of a new 2‐amino‐glycan,poly‐(1→6)‐α‐D‐mannosamine,by ring‐opening polymerization of 1,6‐anhydro‐mannosamine derivatives

A stereoregular 2‐amino‐glycan composed of a mannosamine residue was prepared by ring‐opening polymerization of anhydro sugars. Two different monomers, 1,6‐anhydro‐2‐azido‐mannose derivative ( 3 ) and 1,6‐anhydro‐2‐(N, N‐dibenzylamino)‐mannose derivative ( 6 ), were synthesized and polymerized. Although 3 gave merely oligomers, 6 was promptly polymerized into high polymers of the number‐average molecular weight (M_n) of 2.3 × 10⁴ to 2.9 × 10⁴ with 1,6‐α stereoregularity. The differences of polymerizability of 3 and 6 from those of the corresponding glucose homologs were discussed. It was found that an N‐benzyl group is exceedingly suitable for protecting an amino group in the polymerization of anhydro sugars of a mannosamine type. The simultaneous removal of O‐ and N‐benzyl groups of the resulting polymers was achieved by using sodium in liquid ammonia to produce the first 2‐amino‐glycan, poly‐(1→6)‐α‐D ‐mannosamine, having high molecular weight through ring‐opening polymerization of anhydro sugars.© 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Scalable ambient synthesis of water‐soluble poly(β‐hydroxythio‐ether)s

Proton transfer polymerization through thiol‐epoxy “click” reaction between commercially available and hydrophilic di‐thiol and di‐epoxide monomers is carried out under ambient conditions to furnish water‐soluble polymers. The hydrophilicity of monomers permitted use of aqueous tetrahydrofuran as the reaction medium. A high polarity of this solvent system in turn allowed for using a mild catalyst such as triethylamine for a successful polymerization process. The overall simplicity of the system translated into a simple mixing of monomers and isolation of the reactive polymers in an effortless manner and on any scale required. The structure of the resulting polymers and the extent of di‐sulfide defects are studied with the help of 13C‐ and ¹H‐NMR spectroscopy. Finally, reactivity of the synthesized polymers is examined through post‐polymerization modification reaction at the backbone sulfur atoms through oxidation reaction. The practicality, modularity, further functionalizability, and water solubility aspects of the described family of new poly(β‐hydroxythio‐ether)s is anticipated to accelerate investigations into their potential utility in bio‐relevant applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 3381–3386     

Synthesis and chemical modification of hyperbranched polyethers with terminal hydroxy groups by the anionic ring‐opening polymerization of 3‐alkyl‐3‐hydroxymethyl oxetanes

The anionic ring‐opening polymerization of oxetanes containing hydroxyl groups was carried out with potassium tert‐butoxide as an initiator in the presence of 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding multifunctional hyperbranched polymers: poly(3‐ethyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 2200–4100 in 83–95% yields, and poly(3‐methyl‐3‐hydroxymethyloxetane)s, with number‐average molecular weights of 4600–5200 in 70–95% yields. The synthesized poly(3‐ethyl‐3‐hydroxymethyloxetane)s and poly(3‐methyl‐3‐hydroxymethyloxetane)s were hyperbranched polyethers containing an oxetane moiety and many hydroxy groups at the ends. The postpolymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane)s was performed in the presence of potassium tert‐butoxide and 18‐crown‐6‐ether in N‐methylpyrrolidinone at 180 °C; it yielded corresponding polymers with higher molecular weights in good yields. The cationic polymerization of poly(3‐ethyl‐3‐hydroxymethyloxetane) derivatives was carried out with boron trifluoride etherate as an initiator and was followed by alkaline hydrolysis; this yielded a new branched polymer, a poly(hyperbranched polyether), with many pendant hydroxy groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3739–3750, 2004     

Synthesis,characterization, and thermal properties of a novel pentaerythritol‐initiated star‐shaped poly(p‐dioxanone)

A novel star‐shaped poly(p‐dioxanone) was synthesized by the ring‐opening polymerization of p‐dioxanone initiated by pentaerythritol with stannous octoate as a catalyst in bulk. The effect of the molar ratio of the monomer to the initiator on the polymerization was studied. The polymers were characterized with ¹H NMR and ¹³C NMR spectroscopy. The thermal properties of the polymers were investigated with differential scanning calorimetry and thermogravimetric analysis. The novel star‐shaped poly(p‐dioxanone) has a potential use in biomedical materials. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1245–1251, 2006     

Synthesis and characterization of highly fluorinated poly(phthalazinone ether)s based on AB‐type monomers

Four different fluorinated methyl‐ and phenyl‐substituted 4‐(4‐hydroxyphenyl)‐2‐(pentafluorophenyl)‐phthalazin‐1(2H)‐ones, AB‐type phthalazinone monomers, have been successfully synthesized by nucleophilic addition–elimination reactions of methyl‐ and phenyl‐substituted 2‐((4‐hydroxy)benzoyl)benzoic acid with 1‐(pentafluorophenyl)hydrazine. Under mild reaction conditions, the AB‐type monomers underwent self‐condensation polymerization reactions successfully and gave fluorinated poly(phthalazinone ether)s with high molecular weights. Detailed structural characterization of the AB‐type monomers and fluorinated polymers was determined by ¹H NMR, ¹⁹F NMR, FTIR, and GPC. The solubility, thermal properties, mechanical properties, water contact angles, and optical absorption of the polymers were evaluated. The polymers had high T_gs varying from 337 to 349 °C and decomposition temperatures (T_{d, 25} wt %) above 409 °C. Tough, flexible films were cast from THF and chloroform solutions. The films showed excellent tensile strengths ranging from 70 to 85 MPa with good hydrophobicities with water contact angles higher than 95.5 °C. The polymers had absorption edges below 340 nm and very low absorbance per cm at higher wavelengths 500–2500 nm. These results indicate that the polymers are promising as high performance materials, for example, membranes and hydrophobic materials. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1761–1770     

Synthesis of biocompatible and biodegradable block copolymers of polyvinyl alcohol‐block‐poly(ε‐caprolactone) using metal‐free living cationic polymerization

Applications of metal‐free living cationic polymerization of vinyl ethers using HCl · Et₂O are reported. Product of poly(vinyl ether)s possessing functional end groups such as hydroxyethyl groups with predicted molecular weights was used as a macroinitiator in activated monomer cationic polymerization of ε‐caprolactone (CL) with HCl · Et₂O as a ring‐opening polymerization. This combination method is a metal‐free polymerization using HCl · Et₂O. The formation of poly(isobutyl vinyl ether)‐b‐poly(ε‐caprolactone) (PIBVE‐b‐PCL) and poly(tert‐butyl vinyl ether)‐b‐poly(ε‐caprolactone) (PTBVE‐b‐PCL) from two vinyl ethers and CL was successful. Therefore, we synthesized novel amphiphilic, biocompatible, and biodegradable block copolymers comprised polyvinyl alcohol and PCL, namely PVA‐b‐PCL by transformation of acid hydrolysis of tert‐butoxy moiety of PTBVE in PTBVE‐b‐PCL. The synthesized copolymers showed well‐defined structure and narrow molecular weight distribution. The structure of resulting block copolymers was confirmed by ¹H NMR, size exclusion chromatography, and differential scanning calorimetry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5169–5179, 2009     

Synthesis and in vitro activity of platinum containing 2‐oxazoline‐based glycopolymers

We report the synthesis of glyco(poly(2‐oxazoline)s) functionalized with Pt(II) units for targeted tumor applications. To this end, poly(2‐ethyl‐2‐oxazoline‐block‐2‐(3‐butenyl)‐2‐oxazoline) is modified with thiol‐modified acetyl protected glucose and galactose, respectively, and terpyridine (tpy) units using thiol‐ene photoaddition. Deprotection of the sugars with sodium methoxide and treatment with Pt(COD)Cl₂ applying a mild synthesis route yields polymers with monosaccharide targeting moieties and cytotoxic Pt(II) units. The polymers and intermediates are characterized by ¹H nuclear magnetic resonance spectroscopy and size exclusion chromatography. Subsequently, the hemolytic activity, induction of erythrocyte aggregation as well as the cytotoxicity against mouse fibroblast L929 cells, human embryonic kidney cells HEK 293, and human hepatocytes HepG2 are studied. The comparison to cisplatin, the standard for cancer therapy, demonstrates the potential of the presented system. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2703–2714     

Ring‐opening polymerization of lipoic acid and characterization of the polymer

Thermal polymerization of DL ‐α‐lipoic acid (LPA) in bulk without any initiator proceeded easily above the melting point of LPA. The molecular weight polymer determined by GPC was high. From the ¹H NMR spectra of polymers, poly(LPA) obtained from polymerization of high purity LPA was to consist of cyclic structures, which was confirmed by ESI‐MS. Interlocked polymer consisting of poly(LPA) and dibenzo‐30‐crown‐10 entangled with each other was synthesized by the polymerization of LPA in the presence of dibenzo‐30‐crown‐10. From the DSC analysis of the polymers, glass transition temperature was estimated to be about ?11 °C, but melting point was not observed, indicating that poly(LPA) is an amorphous polymer. By photodecomposition of poly(LPA), M_n was rapidly decreased at the early stage of the decomposition. After that, the M_n of the polymer kept and then was almost constant even for a prolonged reaction time. On the basis of the results, it would be presumed that poly (LPA) obtained form polymerization of high purity LPA includes an interlocked structure. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Polyrotaxanes by free‐radical polymerization of acrylate and methacrylate monomers in the presence of a crown ether

Poly[(methyl acrylate)‐rotaxa‐(30‐crown‐10)] ( 5 ) and poly[(methyl methacrylate)‐rotaxa‐(30‐crown‐10)] ( 6 ) were synthesized by azobisisobutyronitrile‐initiated free‐radical bulk polymerizations of the respective monomers in the presence of 30‐crown‐10 ( 1 ; equimolar; 5 times the monomer mass). For 5 , 3.8 mass % (0.81 mol % with respect to the monomer) of the crown was incorporated versus 1.7 mass % (0.39 mol % with respect to the monomer) for 6 . Control reactions with 18‐crown‐6, which is to small to be threaded, showed that chain transfer to the crown ethers was detectable only for the acrylate but was relatively negligible and spectroscopically distinct. The threading yields were much higher with these systems than with polystyrene, most likely because of the greater compatibility of the crown ether with these polar monomers and polymers and the consequent ability to carry out the polymerizations homogeneously in the absence of added solvent; however, the threading process was still essentially statistical. Therefore, the polymerization of methacrylate monomers 8a – 8c based on tetraarylmethane moieties connected via diethyleneoxy or triethyleneoxy spacers was examined in the presence of 1 in the belief that the supramolecular semirotaxane monomer 9 formed statistically in situ could be captured more efficiently and produce higher threading yields, presumably of side‐chain polyrotaxanes, than the simple (meth)acrylate monomers. Azobisisobutyronitrile‐initiated polymerizations either neat or in toluene produced polyrotaxanes 10 with up to about 1.6 mass % and 2 mol % threaded crown ether, presumably trapped on the pendant stoppered side chains. Although primarily statistical in nature, the latter rotaxane syntheses afforded on a molar basis 3–7 times more efficient incorporation of 1 than styrene (0.33 mol %), methyl acrylate (0.81 mol %), or methyl methacrylate (0.39 mol %) monomers for the preparation of main‐chain polypseudorotaxanes and indeed even surpassed the 60‐crown‐20/polyacrylonitrile system (1.5 mol %). This was presumed to be due to the fact that the loss of the crown ether, once it was threaded onto the monomer to form 9 and the latter was polymerized, was either retarded (by the tetraphenylmethyl stopper in 10a ) or prevented completely [by tris(p‐t‐butylphenyl)phenylmethyl stoppers in 10b and 10c ]. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1978–1993, 2001     

Hyperbranched polymers generated from oxyanionic vinyl polymerization of commercially available methacrylate inimers

Hyperbranched polymethacrylates were prepared by means of oxyanionic vinyl polymerization of commercially available monomers, including hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methacrylate (PEG‐MA). Hyperbranched polymethacrylates with high molecular weight were obtained with the complex of potassium hydride and 18‐crown‐6 as the initiator. The effect of 18‐crown‐6 is very important, and only oligomer can be obtained in the polymerization without 18‐crown‐6. The molecular structure of the hyperbranched polymers was confirmed with ¹H NMR and ¹³C NMR spectra. The ratio of initiator to monomer significantly affects the architecture of the resultant polymers. When the ratio of initiator to monomer equals 1 in the oxyanionic vinyl polymerization of HEMA, the degree of branching of the resulting polymer was calculated to be around 0.49. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3502–3509, 2005     

ɛ‐caprolactone and lactide polymerization promoted by an ionic titanium(IV)/iron(III) polynuclear halo‐alkoxide

The ionic [Ti₃(µ₃‐OPrⁱ)₂(µ‐OPrⁱ)₃(OPrⁱ)₆][FeCl₄] halo‐alkoxide ( A ) was investigated for its activity towards the bulk polymerization of rac‐lactide (rac‐LA) and ?‐caprolactone (?‐CL) in various temperatures, monomer/ A molar proportions, and reaction times. The reactivity of A in the ring‐opening polymerization (ROP) of both monomers is mainly due to the cationic [Ti₃(OPrⁱ)₁₁]⁺ unity and proceeds through the coordination–insertion mechanism. Molecular weights ranging from 6,379 to 13,950 g mol^?1 and PDI values varying from 1.22 to 1.52 were obtained. Results of ROP kinetic studies for both ?‐CL and rac‐LA confirm that the reaction rates are first‐order with respect to monomers. The production of poly(?‐caprolactone) shows a higher sensitivity of the reaction rate to temperature, while the polymerization of rac‐LA is slower and more dependent on the thermal stability of the active species during the propagation step. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2509–2517     

“Push‐pull” supramolecular chromophores supported on cyclopolymers

Well‐defined macromolecules have been obtained through free‐radical cyclopolymerization and cyclocopolymerization of difunctional and acrylic‐like monomers, which contained “push‐pull” supramolecular chromophores, able to form 1:1 complexes with Eu³⁺ ions in solution. The monomeric molecular modules are built around bismalonate crown ethers in a convergent fashion, in which one of the malonate moiety is derivatized as the ylidene malonate push‐pull fragment, and the other malonate moiety is elaborated to introduce two polymerizable and acrylic‐like substituents. The free‐radical induced cyclopolymerization of these monomers, or their cyclocopolymerization with UV/Vis “silent” but structurally related monomers, afforded macromolecular architectures characterized by GPC, NMR and DSC techniques. UV/Vis titration studies, performed with Eu(OTf)₃ as the supramolecular probe, revealed how adjacent chromophores within the polymeric backbone are virtually independent from each other, and how the binding ability towards the probe of these multivalent, highly packed cyclopolymeric architectures, although reduced, is still clearly detectable. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5202–5213, 2008     

Tuning the LCST of poly(2‐cyclopropyl‐2‐oxazoline) via gradient copolymerization with 2‐ethyl‐2‐oxazoline

Poly(2‐propyl‐oxazoline)s can be prepared by living cationic ring‐opening polymerization of 2‐oxazolines and represent an emerging class of biocompatible polymers exhibiting a lower critical solution temperature in aqueous solution close to body temperature. However, their usability is limited by the irreversibility of the transition due to isothermal crystallization in case of poly(2‐isopropyl‐2‐oxazoline) and the rather low glass transition temperatures (T_g < 45 °C) of poly(2‐n‐propyl‐2‐oxazoline)‐based polymers. The copolymerization of 2‐cyclopropyl‐2‐oxazoline and 2‐ethyl‐2‐oxazoline presented herein yields gradient copolymers whose cloud point temperatures can be accurately tuned over a broad temperature range by simple variation of the composition. Surprisingly, all copolymers reveal lower T_gs than the corresponding homopolymers ascribed to suppression of interchain interactions. However, it is noteworthy that the copolymers still have T_gs > 45 °C, enabling convenient storage in the fridge for future biomedical formulations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3118–3122     

Living anionic polymerization of N‐methoxymethyl‐N‐isopropylacrylamide: Synthesis of well‐defined poly(N‐isopropylacrylamide) having various stereoregularity

Anionic polymerization of N‐methoxymethyl‐N‐isopropylacrylamide ( 1 ) was carried out with 1,1‐diphenyl‐3‐methylpentyllithium and diphenylmethyllithium, ‐potassium, and ‐cesium in THF at ?78 °C for 2 h in the presence of Et₂Zn. The poly( 1 )s were quantitatively obtained and possessed the predicted molecular weights based on the feed molar ratios between monomer to initiators and narrow molecular weight distributions (M_w/M_n = 1.1). The living character of propagating carbanion of poly( 1 ) either at 0 or ?78 °C was confirmed by the quantitative efficiency of the sequential block copolymerization using N,N‐diethylacrylamide as a second monomer. The methoxymethyl group of the resulting poly( 1 ) was completely removed to give a well‐defined poly(N‐isopropylacrylamide), poly(NIPAM), via the acidic hydrolysis. The racemo diad contents in the poly(NIPAM)s could be widely changed from 15 to 83% by choosing the initiator systems for 1 . The poly(NIPAM)s obtained with Li⁺/Et₂Zn initiator system possessed syndiotactic‐rich configurations (r = 75–83%), while either atactic (r = 50%) or isotactic poly(NIPAM) (r = 15–22%) was generated with K⁺/Et₂Zn or Li⁺/LiCl initiator system, respectively. Atactic and syndiotactic poly(NIPAM)s (42 < r < 83%) were water‐soluble, whereas isotactic‐rich one (r < 31%) was insoluble in water. The cloud points of the aqueous solution of poly(NIPAM)s increased from 32 to 37 °C with the r‐contents. These indicated the significant effect of stereoregularity of the poly(NIPAM) on the water‐solubility and the cloud point in water © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4832–4845, 2006     

The application of copper(II) deactivator on the single‐electron transfer living radical polymerization of tert‐butyl acrylate

We demonstrate the living radical polymerization of tert‐butyl acrylate (tBA) applying the SET mechanism, employing methyl 2‐bromopropionate (MBP) as initiator in dimethyl sulfoxide (DMSO) at ambient temperature. It is observed that introducing copper bromide into the catalyst system is necessary for controlling on the SET‐LRP polymerization of tBA. In this work, we make major investigation for the effect of the different stoichiometry quantity of copper bromide on the polymerization. Experiments show that the polymerization achieves better control with increasing the stoichiometry quantity of copper(II) deactivator. The structural analysis of the resulting polymers by ¹H NMR demonstrates the successful synthesis of poly(tBA)s by SET‐LRP in DMSO. Moreover, this work is helpful to the SET‐LRP of other monomers and is expected to expand the application of SET‐LRP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2793–2797, 2010     

Spacer‐length‐dependent association in polymers with multiple‐hydrogen‐bonded end groups

Herein, we investigate the influence of spacer length on the homoassociation and heteroassociation of end‐functionalized hydrogen‐bonding polymers based on poly(n‐butyl acrylate). Two monofunctional ureido‐pyrimidinone (UPy) end‐functionalized polymers were prepared by atom transfer radical polymerization using self‐complementary UPy‐functional initiators that differ in the spacer length between the multiple‐hydrogen‐bonding group and the chain initiation site. The self‐complementary binding strength (K_dim) of these end‐functionalized polymers was shown to depend critically on the spacer length as evident from ¹H NMR and diffusion‐ordered spectroscopy. In addition, the heteroassociation strength of the end‐functionalized UPy polymers with end‐functionalized polymers containing the complementary 2,7‐diamido‐1,8‐naphthyridine (NaPy) hydrogen‐bond motif is also affected when the aliphatic spacer length is too short. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of 4μ‐PS2PEO2, 4μ‐PS2PCL2, 4μ‐PI2PEO2, and 4μ‐PI2PCL2 star‐shaped copolymers by the combination of glaser coupling with living anionic polymerization and ring‐opening polymerization

4μ‐A₂B₂ star‐shaped copolymers contained polystyrene (PS), poly(isoprene) (PI), poly(ethylene oxide) (PEO) or poly(ε‐caprolactone) (PCL) arms were synthesized by a combination of Glaser coupling with living anionic polymerization (LAP) and ring‐opening polymerization (ROP). Firstly, the functionalized PS or PI with an alkyne group and a protected hydroxyl group at the same end were synthesized by LAP and then modified by propargyl bromide. Subsequently, the macro‐initiator PS or PI with two active hydroxyl groups at the junction point were synthesized by Glaser coupling in the presence of pyridine/CuBr/N,N,N ′,N ″,N ″‐penta‐methyl diethylenetri‐amine (PMDETA) system and followed by hydrolysis of protected hydroxyl groups. Finally, the ROP of EO and ε‐CL monomers was carried out using diphenylmethyl potassium (DPMK) and tin(II)‐bis(2‐ethylhexanoate) (Sn(Oct)₂) as catalyst for target star‐shaped copolymers, respectively. These copolymers and their intermediates were well characterized by SEC, ¹H NMR, MALDI‐TOF mass spectra and FT‐IR in details. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Oxo‐crown‐ethers as comonomers for tuning polyester properties

2‐Oxo‐12‐crown‐4‐ether (OC) was procured in a novel, two‐step procedure in a 37% overall yield. This interesting hydrophilic lactone was effectively polymerized with Novozym 435 as the catalyst: within 10 min, the monomer conversion was greater than 95%. Poly(2‐oxo‐12‐crown‐4‐ether) [poly(OC)] was obtained as a viscous oil with a glass‐transition temperature of approximately ?40 °C, and it was soluble in water. Subsequently, OC was copolymerized with ω‐pentadecanolactone (PDL). A kinetic evaluation of both monomers showed that for OC, the Michaelis–Menten constant (K_M) and the maximal rate of polymerization (V_max) were 2.7 mol/L and 0.24 mol/L min, respectively, whereas for PDL, K_M and V_max were 0.5 mol/L and 0.09 mol/L min, respectively. Although OC polymerized five times faster than PDL, ¹H NMR analysis of the copolymers revealed a random copolymer structure. Differential scanning calorimetry traces of the copolymers showed that they were semicrystalline and that the melting temperature and melting enthalpy of the copolymers linearly decreased with an increasing amount of OC. The melting temperature of the copolymers could be adequately predicted by the Baur equation, and this suggested that poly (OC) was rejected from the poly(ω‐pentadecanolactone) [poly(PDL)] crystals. Solid‐state NMR studies confirmed that the crystalline phase exclusively consisted of poly (PDL), whereas the amorphous phase was a mixture of OC and PDL units. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2166–2176, 2006     

Synthesis of helical polyisocyanides bearing aza‐crown ether groups as pendant

We, herein, present a novel synthesis of responsive helical poly(aryl isocyanide)s bearing aza‐crown ethers as pendant groups. Chiral aryl isocyanide monomers bearing an aza‐crown ether as a pendant were designed and synthesized, piror to polymerization using a Pd‐Pt µ‐ethynediyl complex as an initiator to give the corresponding polymers in good yield. The resulting polyisocyanides adopted a stable helical structure in solution, as confirmed by circular dichroism spectroscopic analysis. In addition, the polymers were soluble in various solvents. Furthemore, the addition of suitable alkali metal ions to the crown ether of the sidechain on the helical polyisocyanide to form host‐gest complexes resulted in deformation of the helix due to electrostatic repulsion, and these phenomena depended on the size of metal cations. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 496–504.     

ABC‐type hetero‐arm star terpolymers through “Click” chemistry

Hetero‐arm star ABC‐type terpolymers, poly(methyl methacrylate)‐polystyrene‐poly(tert‐butyl acrylate) (PMMA‐PS‐PtBA) and PMMA‐PS‐poly(ethylene glycol) (PEG), were prepared by using “Click” chemistry strategy. For this, first, PMMA‐b‐PS with alkyne functional group at the junction point was obtained from successive atom transfer radical polymerization (ATRP) and nitroxide‐mediated radical polymerization (NMP) routes. Furthermore, PtBA obtained from ATRP of tBA and commercially available monohydroxyl PEG were efficiently converted to the azide end‐functionalized polymers. As a second step, the alkyne and azide functional polymers were reacted to give the hetero‐arm star polymers in the presence of CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine ( PMDETA) in DMF at room temperature for 24 h. The hetero‐arm star polymers were characterized by ¹H NMR, GPC, and DSC. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5699–5707, 2006