Block and star block copolymers by mechanism transformation. II. Synthesis of poly(DOP‐b‐St) by combination of ATRP and CROP

Styrene underwent the ATRP process using an asymmetric difunctional initiator, 2‐hydroxylethyl 2′‐bromobutyrate in combination with CuBr and 2,2′‐bipyridine (bpy). Polystyrene with hydroxyl and bromine groups at each end of the polymer (HO‐PSt‐Br) was obtained, and used as a chain‐transfer agent in the cationic ring‐opening polymerization of 1,3‐dioxepane with triflic acid as initiator. The structures of the polymerization products were analyzed by ¹H NMR and GPC analyses, indicating the formation of block copolymer. The molecular weight distribution of the block copolymer was relatively narrow and the molecular weight of the polyDOP block was high. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 436–443, 2000     

Structural features of polymeric silicon glycerolate hydrogels

Structural features of polymeric silicon glycerolate hydrogels based on tetrafunctional silicon glycerolates were investigated using model process, namely, hydrolytic transformation of difunctional silicon glycerolates, by IR and ¹H NMR spectroscopy, elemental analysis, atomic emission spectrometry. The possibility of forming a polymer network containing Si—O—Si and Si—OCH₂CH(OH)CH₂O—Si fragments was demonstrated. The molecular weight of the sub-chains in the network was calculated using Flory—Rehner approach based on the mechanical properties of the swollen network of flexible polymeric chains.     

Bilateral, difunctional nanosphere aggregates and their assembly mediated by polymer chains

We have developed an efficient method for producing difunctional, bilateral nanospheres. A monolayer of nanoparticles was prepared followed by deposition of a thin layer of metal. By varying the base particle and metal deposited, bilateral nanoparticles were formed. The different regions of the nanoparticles were selectively functionalized with polymer linkers containing specific terminal groups, thereby creating bilateral, difunctional nanoparticles. Subsequent covalent cross-linking of different nanoparticles enabled the formation of stable architectures with programmed hierarchy and controlled chemical composition.     

Cyclic poly(ε‐caprolactone) synthesized by combination of ring‐opening polymerization with ring‐closing metathesis,ring closing enyne metathesis,or “click” reaction

This article described the synthesis of cyclic poly(ε‐caprolactone) (PCL) via ring‐closing metathesis (RCM), ring closing enyne metathesis (RCEM), and “click” reaction of different difunctional linear PCL. Linear PCL precursors were prepared by ring‐opening polymerization (ROP) of ε‐caprolactone in bulk using 10‐undecen‐1‐ol or propargyl alcohol as the initiator, followed by reacting with corresponding acyl chloride containing vinyl or azido end group. The subsequent end‐to‐end intramolecular coupling reactions were performed under high dilution conditions. The successful transformation of linear PCL precursor to cyclic PCL was confirmed by Gel permeation chromatography, ¹H NMR, and Fourier transform infrared measurements. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3022–3033, 2009     

Synthesis and characterisation of novel PBT and PCCD telechelic ionomers prepared by end capping

Poly(butylene terephthalate) (PBT) and poly(1,4-cyclohexylenedimethylene 1,4-cyclohexanedicarboxylate) (PCCD) ionomers containing terminal ionic units, derived from a novel sodiosulfonate epoxy molecule, were synthesised using an end capping technique in solution. The sulfonated epoxide has the fundamental feature of selectively reacting with the polymer carboxylic terminal groups and therefore, creating polymers with terminal ionic groups. The presence of the sodiosulfonate end groups was confirmed by ¹H NMR spectroscopy and titration of carboxyl end groups. Differential scanning calorimetry (DSC) indicated that the presence of ionic end groups has a different effect on the crystallisation process. In particular in PBT the ionic groups cause an increment of the crystallisation rate, whereas, in PCCD the opposite effect is observed.     

End‐group modified poly(methyl vinyl ether): Characterization and LCST demixing behavior in water

A range of hydrophilic poly(methyl vinyl ether) (PMVE) polymers was synthesized by living cationic polymerization of methyl vinyl ether (MVE), having different hydrophilic or hydrophobic chain‐end functionalities. The dissimilar end‐groups were either introduced by end‐capping of the growing polymer chain with LiBH₄, methanol, and water or by functional initiation with 2‐bromo‐(3,3‐diethoxy‐propyl)‐2‐methylpropanoate. The synthesized PMVEs were characterized by ¹H NMR, size exclusion chromatography, and matrix‐assisted laser desorption ionization time of flight, displaying a narrow polydispersity. Modulated temperature DSC was applied to study the influence of the nature of the end‐groups on the solubility behavior of PMVE in water. Terminal‐modification with a hydroxyl function improves the solubility, whereas a Br‐containing end‐group causes the polymer to be insoluble in water at room temperature; however, the special type III lower critical solution temperature demixing behavior being maintained. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 461–469, 2006     

Surface‐initiated atom transfer radical polymerization grafting of poly(2,2,2‐trifluoroethyl methacrylate) from flat silicon wafer surfaces

Poly(2,2,2‐trifluoroethyl methacrylate) (PTFEMA), a partially fluorinated polymer, was directly grafted from silicon wafer surfaces by a surface‐initiated atom‐transfer radical polymerization (ATRP). The polymer layer thickness increased linearly with monomer conversion and molecular weight of free polymers in solution. The thickness was mainly determined by the experimental conditions such as activator/deactivator ratio, monomer/catalyst ratio, and monomer concentration. PTFEMA layers of more than 100‐nm thick were obtained. The grafted PTFEMA chains were “living” and allowed the extension of a second block of PMMA. X‐ray photoelectron spectroscopy study showed that the chemical compositions at the surfaces agreed well with their theoretical values. A novel surface‐attachable difunctional initiator was also synthesized and applied to the grafting of PTFEMA. The grafting density was doubled using this difunctional initiator, from 0.48 to 0.86 chains/nm². © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1252–1262, 2006     

Application of Dipotassium Glycoxides–Activated 18-Crown-6 for the Synthesis of Poly(propylene oxide) with Increased Molar Mass

Mono- and dipotassium salts of dipropylene glycol were applied for the polymerization of propylene oxide in mild conditions, i.e., tetrahydrofuran solution at ambient temperature. The structure of polymers was investigated by use of ¹³C NMR and MALDI-TOF techniques. The structure depends strongly on the kind of initiator and additives that are used such as coronand 18-crown-6 and dipropylene glycol. The lowest unsaturation, represented by allyloxy starting groups, has the polymer obtained by use of monopotassium salt without the ligand. The highest unsaturation degree is for the polymer synthesized in the presence of dipotassium salt–activated 18-crown-6. This polymer, obtained at high initial monomer concentration and low initial concentration of initiator, consists of two fractions, i.e., a low molar mass fraction (M_n = 9400) containing mainly macromolecules with alkoxide starting and end groups and a much higher molar mass fraction (M_n = 29500 g/mol) containing macromolecules with allyloxy starting groups and alkoxide or hydroxyl end groups. Addition of free glycol to this system decreases the molar mass of polymers. Similar results were obtained by use of dipotassium salts of other glycols. The mechanisms of the studied processes are discussed.     

聚苯乙烯-b-聚硅氧烷-b-聚苯乙烯三嵌段共聚物的合成及表征

采用乙烯基封端的聚 (二甲基硅氧烷 )与溴化氢反应制得末端含有C Br的双官能聚 (二甲基硅氧烷 ) ,以此聚 (二甲基硅氧烷 )大分子为引发剂 ,CuCl为催化剂 ,4 ,4′ 二 (5 壬基 ) 2 ,2′ 联吡啶为配体 ,通过原子转移自由基聚合法 ,制得分子量和结构可控的聚苯乙烯 b 聚硅氧烷 b 聚苯乙烯 (PSt b PDMS b PSt)共聚物 .     

Preparation of microporous polymers in the form of particles and a thin film from hyperbranched polyphenylenes

The use of a hyperbranched polymer as a building block for the synthesis of a microporous organic polymer was demonstrated. Hyperbranched polyphenylenes (HBPs) were prepared from (3,5‐dibromophenyl)boronic acid, which contained numerous unreacted bromophenyl end groups. Utilizing metal‐catalyzed coupling reactions between these functional groups, cross‐linked porous polymers were obtained. Although the HBPs did not show porosity, their cross‐linked polymers had highly porous structures with Brunauer–Emmett–Teller surface areas of up to 2030 m²/g. An insoluble porous thin film was fabricated by spin casting of a solution containing a HBP followed by Sonogashira cross‐coupling reaction. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2336–2342     

Polymerization of methyl methacrylate with ceric ion-methanol redox system

The polymerization of methyl methacrylate initiated by Ce⁴⁺ methanol redox system was studied in aqueous solution of nitric acid at 15°C. The polymerization was initiated by primary radicals formed from Ce⁴⁺/alcohol complex. Poly(methyl methacrylate) chains containing the alcohol residue were obtained. Variations in the temperatuare and concentration of the components of the redox system allowed the control of the rate of polymerization and molecular weight of the polymer. The concentration of the hydroxyl end groups in the poly(methyl methacrylate) of low molecular weight was determined by titration and by spectrometric method.     

High-temperature,high-resolution nuclear magnetic resonance of poly (p-phenylene sulfide)

A high-temperature, high-resolution ¹³C nuclear magnetic resonance spectroscopy technique was developed for the analysis of poly (p-phenylene sulfide) (HT/HR NMR of PPS). This technique can be applied to the identification and quantitative analysis of end groups and polymer structure in high-temperature polymers where solution temperatures above 200°C are required for analysis. Verification of calculated ¹³C NMR shift values of chloro-terminated and hydrogen-terminated end groups was made by HT/HR NMR of two oligo (p-phenylene sulfide) model compounds. Identification of the chlorine end group was made in high-molecular weight PPS. On the high-molecular weight PPS, identification and quantitative analysis of amino and N-alkylamino end groups were possible only after derivatization of the polymer with ¹³C-enriched benzoyl chloride.     

Polyethynylferrocene

The completely conjugated polymer, polyethynylferrocene, was prepared by heating ethynylferrocene with catalytic amounts of azobisisobutyronitrile to 180-240[ddot] under nitrogen in bulk. Cyclotrimerization competes with polymerization under these conditions. Pure low molecular weight polyethynylferrocene was isolated and characterized by IR and NMR spectroscopy and by a gel permeation chromatography. The pure polymer exhibits a conductivity of 2 × 10^{?14 ?1} cm^?1. Attempts to prepare polyethynylferrocene by heating acetylferrocene in molten zinc chloride were, contrary to literature reports, unsuccessful. A polymer containing hydroxyl and keto groups was obtained, and extensive degradation of the ferrocene groups occurred. The general reaction scheme is discussed. It includes cleavage of cyclopentadienyl rings from ferrocene and the incorporation of cyclopentane rings into the polymer structure.     

Photopolymerization of difunctional cyclopolymerizable monomers with low shrinkage behavior

Cyclopolymerizable monomers (CPM) have been the focus of investigations for over 70 years due to favorably low shrinkage upon polymerization, yet little research dealt with difunctional CPMs, especially in the field of radical photopolymerization. Herein, we synthesized novel difunctional 1,6-diene CPMs based on the isomeric mixture of (2,2,4)/(2,4,4)-trimethylhexane-1,6-diamine as spacer unit, which undergoes cyclopolymerization forming five- or six-membered ring structures in the polymer backbone upon photopolymerization. Different photopolymerizable moieties (allyl-, methacryloyl-, and ester-activated allyl-moieties) were chosen for modification of the spacer unit to investigate their influence on reactivity and shrinkage behavior. The (thermo)mechanical properties of the cured difunctional 1,6-diene CPMs further reveal the effect of reactivity-enhancing electron-withdrawing groups (e.g., ester and carbonyl groups) on the final polymer network. For comparison, similar difunctional monoene compounds were are also synthesized and characterized to illustrate the low shrinkage behavior of the novel difunctional 1,6-diene CPMs.     

Dendronized polymers via Diels–Alder “click” reaction

A modular approach toward the synthesis of polymers containing dendron groups as side chains is developed using the Diels–Alder “click” reaction. For this purpose, a styrene‐based polymer appended with anthracene groups as reactive side chains was synthesized. First through third‐generation polyester dendrons containing furan‐protected maleimide groups at their focal point were synthesized. Facile, reagent‐free, thermal Diels–Alder cycloaddition between the anthracene‐containing polymer and latent‐reactive dendrons leads to quantitative functionalization of the polymer chains to afford dendronized polymers. The efficiency of this functionalization step was monitored using ¹H and ¹³C NMR spectroscopy and FTIR and UV–vis spectrometry. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 410–416, 2010     

The synthesis of diene and vinyl copolymers containing predetermined quantities of polynuclear hydrocarbon or heterocyclic adducts—VII: Copolymers formed from butadiene,a heterocyclic compound and some linking or terminating agents

The reaction of butadiene (M) and a suitable heterocyclic molecule (A) (acridine, quinoline or puridine) with lithium metal in tetrahydrofuran (THF) produced polymeric adducts of structure ^?A—M_n—A^? where the negative charges are located on the nitrogen atoms. Similar products (mono or difunctional) may be produced by reacting living polybutadiene directly with these heterocyclic molecules. In the case of acridine, proton termination produced oligomers terminated with dihydroacridine groups; polymeric species containing amide linkages can be produced by titration with adipoyl chloride and, although this reaction is in itself efficient, the product easily re-aromatizes. With quinoline and pyridine, the dihydroadducts become progressively less stable, showing strong tendencies to re-aromatise and crosslink. It is shown that the anionic pyridine adduct of polybutadiene may be cleanly re-aromatised to produce pyridine-terminated polymers which are stable. These pyridine groups can be reacted with benzyl halides to produce pyridinium salts; the presence of these ionic groups has a profound effect on the physical properties of the product. Reaction with p-xylylene dibromide converts low molecular weight difunctional pyridine-terminated polybutadiene from a mobile liquid to a rubbery solid; the material remains soluble and so is free from chemical crosslinks.     

Sorption of ethanesulfonic acid by nylon-6 containing various numbers of end groups

From the analysis of the permeation of ³⁵S labeled ethanesulfonic acid, through nylon-6 films sorption isotherms were obtained. The films are characterized by their largely different content of carboxyl and amino end groups. It was found that the shape of the isotherm depends on the molar ratio of the two end groups: an S-shape curve for the film containing the carboxyl end group larger than the amino end group and a Langmuir-type curve for the film containing comparable numbers of end groups. These results were explained by the McGregor-Harris theory in which the acid dissociation constants of the two end groups in nylon were estimated experimentally.     

Synthesis of ω‐ and α,ω‐sulfonatotelechelics based on homopolymers and block copolymers of n‐butyl methacrylate and t‐butyl methacrylate

The synthesis of ω‐ and α,ω‐telechelics with sulfonate end groups through the sulfoalkylation of homopolymers and block copolymers of n‐butyl methacrylate and t‐butyl methacrylate with 1,3‐propane sultone is described. The polymerizations are initiated in tetrahydrofuran at −78 °C with either 1,1‐diphenyl‐3‐methylpentyllithium or dilithium 1,1,4,4‐tetraphenylbutane to obtain monofunctional or difunctional polymethacrylate anions, respectively. Narrow molecular weight distributions are obtained for the homopolymers and copolymers in the presence of LiCl in a 10/1 ratio relative to the initiator. The direct reaction of the poly(n‐butyl methacrylate) anions with the sultone results in low functionalization levels: f = 0.24–0.29 for the monofunctional anions and f = 0.32–0.35 for the difunctional anions. The reaction of the poly(t‐butyl methacrylate) anions or end‐capping of the poly(n‐butyl methacrylate) anions with t‐butyl methacrylate units before sulfoalkylation yields telechelics with f = 0.81–1.0 for the monofunctional anions and f = 1.74–1.94 for the difunctional anions. The telechelic polymers, purified by ultrafiltration, have been characterized by size exclusion chromatography, Fourier transform infrared, and ¹H NMR spectroscopy. The yield of the sulfoalkylation reactions, determined by colorimetric analysis of a complex formed with methylene blue, is in good agreement with the results obtained by nonaqueous titration of the acidified telechelics. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3711–3721, 2000     

13C-NMR spectroscopy study of polyurethane obtained from azide hydroxyl-terminated polymer cured with isophorone diisocyanate (IPDI)

Chemical structure investigations of polyurethane binders based on difunctional linear glycidyl azide polymer (GAP) cured with isophorone diisocyanate (IPDI) were performed using ¹³C-NMR spectroscopy in solution. Chemical functions such as urethane, urea, allophanate, and biuret were all expected to be detected in these polymeric binders. ¹³C-NMR assignment of the C O urethane and urea functions were found in these polymers as determined by using model compounds of IPDI. The ¹³C-NMR data gathered in this article can be considered as basic parameters for further characterization of polyurethane structure based on IPDI. Also, ¹³C CP MAS NMR spectra of GAP-IPDI-based polymers were carried out to identify the various chemical functions present in solid polyurethane elastomer. In addition, the curing evolution of a GAP-IPDI-based polymer at 50 and 80°C in bulk was monitored, and the reaction path of the binder was readily determined. Some conclusions on the effects of the cure catalyst and the curing temperature were also drawn. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2991–2998, 1997