Grafted Side Chains Research Articles

Polysulfones tethered with benzimidazole

Benzimidazole units have been grafted onto a polysulfone (PSU) backbone via long alkyl thio–ether chains using a two-step procedure. In the first step, lithiated PSU was reacted with 10-undecenoyl chloride to graft PSU with undecenoyl side chains. The second step involved a free-radical thiol–ene coupling reaction between the C C bonds of the pendant undecenoyl chains and 2-(2-benzimidazolyl)ethanethiol. In this reaction, all the C C bonds were converted into thio–ether linkages without any detectable structural degradation, as confirmed by 1H NMR spectroscopy and size-exclusion chromatography. The procedure constitutes a convenient and general pathway to attach functional or mesogenic groups to PSU via long flexible spacers. Thermogravimetry showed that the benzimidazole-functionalized polymers were stable up to 250 °C under nitrogen atmosphere, and that the first degradation step was attributed to the cleavage of the thio–ether bond. While the grafting of the undecenoyl side chains was found to significantly decrease the glass transition temperature ( T g), the subsequent tethering of the benzimidazole only slightly increased the T g of the grafted PSU backbone. The concentration of benzimidazole was probably too low for the formation of a percolating benzimidazole domain. This explains the quite modest proton conductivity measured under completely dry conditions, e.g. 34 nS/cm at 180 °C for a polymer functionalized with 1.7 benzimidazole units per repeating unit of PSU.

Synthesis, preparation, and conformation of stimulus-responsive end-grafted poly(methacrylic acid-g-ethylene glycol) layers.

Here we report the formation of stimulus-responsive chemically end-grafted "brush-brushes" by synthesizing, mono thiol(end)-functionalized poly(methacrylic acid--ethylene glycol) or poly(MAA--EG) comb-type graft copolymers a combination of protecting group chemistry and atom transfer radical polymerization using the initiator 2-(2,4-dinitrophenylthio)ethyl 2-bromo-2-methyl propionate. The polymers were synthesized with three different molecular weights (15 k, 17 k and 27 k), PEG side chain graft densities (EG/MAA mole ratio = 2.2, 0.4 and 1.9, respectively), and a PEG molecular weight = 1100 and then chemically end-grafted to gold substrates chemisorption, resulting in molecular separation distances of ∼3-4 nm. pH-Dependent swelling was confirmed to take place gradually above pH 4-5 and quantified by heights measured by contact mode AFM imaging of microcontact printed (µCP) samples. Swelling factors (maximum height/minimum height) were fairly large (3.6-7.3) and a decrease in molecular weight by ∼2× and side chain graft density by ∼4× resulted in a decrease in swelling factor by ∼2×. Layer height normal force for all three polymers measured by contact mode atomic force microscope imaging on µCP samples at pH 9 showed a nonlinearly decreasing relationship and complete compression ∼<2 nm for forces >10 nN. At pH 4, all polymer layers were largely collapsed (heights ∼<4 nm) and incompressible (, heights were independent of normal force).

Rheological properties of branched polystyrenes: nonlinear shear and extensional behavior

Nonlinear shear and uniaxial extensional measurements on a series of graft-polystyrenes with varying average numbers and molar masses of grafted side chains are presented. Step-strain measurements are performed to evaluate the damping functions of the melts in shear. The damping functions show a decreasing dependence on strain with an increase in mass fraction of grafted side chains. Extensional viscosities of the melts of graft-polystyrenes exhibit a growing strain hardening with increasing average number of grafted side chains as long as the side branches have a sufficient molar mass to be entangled. Graft-polystyrenes with side arms below the critical molar mass M c for entanglements of linear polystyrene but above the entanglement molar mass M e of linear polystyrene (M e < M w,br < M c) still show a distinct strain hardening. With decreasing molar mass of the grafted side chains (M w,br < M e) the nonlinear-viscoelastic properties of the graft-polystyrene melts approach the behavior for a linear polystyrene with comparable polydispersity.

Rheological properties of branched polystyrenes: linear viscoelastic behavior

Oscillatory shear measurements on a series of branched graft polystyrenes (PS) synthesized by the macromonomer technique are presented. The graft PS have similar molar masses (Mw between 1.3×105 g/mol and 2.4×105 g/mol) and a polydispersity Mw/Mn around 2. The molar masses of the grafted side chains Mw,br range from 6.8×103 g/mol to 5.8×104 g/mol, which are well below and above the critical entanglement molar mass Mc of linear polystyrene. The average number \({\ifmmode\expandafter\bar\else\expandafter\fi{p}}\) of side chains per molecule ranges from 0.6 to 6.7. The oscillatory measurements follow the time–temperature superposition principle. The shift factors do not depend on the number of branches. The zero-shear viscosities of all graft PS are lower than those of linear PS with the same molar mass, which can be attributed to the smaller coil size of the branched molecules. It is shown that the influence of branching on the frequency dependence of the dynamic moduli is weak for all graft PS that were investigated, which can be explained by the low entanglement density.

Rheological properties of branched polystyrenes: linear viscoelastic behavior

Oscillatory shear measurements on a series of branched graft polystyrenes (PS) synthesized by the macromonomer technique are presented. The graft PS have similar molar masses (M w between 1.3×105 g/mol and 2.4×105 g/mol) and a polydispersity M w /M n around 2. The molar masses of the grafted side chains M w,br range from 6.8×103 g/mol to 5.8×104 g/mol, which are well below and above the critical entanglement molar mass M c of linear polystyrene. The average number \({\ifmmode\expandafter\bar\else\expandafter\fi{p}}\) of side chains per molecule ranges from 0.6 to 6.7. The oscillatory measurements follow the time–temperature superposition principle. The shift factors do not depend on the number of branches. The zero-shear viscosities of all graft PS are lower than those of linear PS with the same molar mass, which can be attributed to the smaller coil size of the branched molecules. It is shown that the influence of branching on the frequency dependence of the dynamic moduli is weak for all graft PS that were investigated, which can be explained by the low entanglement density.

Synthesis of Somatostatin Mimetics Based on the 1-Deoxymannojirimycin Scaffold

A novel synthesis of somatostatin mimetics based on the 1-deoxymannojirimycin (DMJ) scaffold has been developed. This involved development of a route suitable for the strategic grafting of pharmacophoric tryptophan and lysine side chains to the nitrogen atom of the piperidine ring and to the primary hydroxyl group of DMJ, respectively. The novel peptidomimetics were found to bind with higher affinity to sst4 receptors than to sst5 receptors.

Thiophene-containing poly(arylene–ethynylene)- alt-poly(arylene–vinylene)s: Synthesis, characterisation and optical properties

This work describes the synthesis and characterisation of two types of thiophene-containing poly(arylene–ethynylene)- alt-poly(arylene–vinylene)s (PAE–PAV) copolymers, whose repeating units (–Ph–C C–Th–CH CH–Ph–CH CH–) n , 5, and (–Th–C C–Ph–C C–Th–CH CH–Ph–CH CH–) n , 8a– c, consist, respectively, of a 1:2 and a 2:2 ratio of triple bond/double bond moieties. Comparison of their photophysical, electrochemical and photovoltaic properties has been carried out. Although similar electrochemical data (HOMO: −5.43 eV, LUMO: ∼−3.15 eV, E g ec = 2.28 eV ) as well as identical thin film absorption behaviour ( λ a=500 nm, E g opt = 2.10 eV ) were obtained for both types of materials, significant differences in their thin film photoluminescence behaviour and photovoltaic properties were observed. While polymer 5 shows a fluorescence maximum at λ e=568 nm (with a fluorescence quantum yield of Φ f=7%), a total fluorescence quenching was observed in 8. Far better photovoltaic performance was obtained from solar cells (set up: ITO/PEDOT:PSS/active layer/LiF/Al; active layer consisting of 5 or 8b as donor and PCBM as acceptor in a 1:3 ratio by weight) designed from 5 than from 8b. Open circuit voltage, V OC, as high as 900 mV and power conversion efficiency, η AM1.5, around 1.2% were obtained. This can be attributed to the 1:2 triple bond/double bond ratio as well as the grafting of shorter octyloxy and 2-ethylhexyloxy side chains in 5 and to its comparatively higher molecular-weight.

Side‐chain crystallization behavior of graft copolymers consisting of amorphous main chain and crystalline side chains: Poly(methyl methacrylate)‐graft‐poly(ethylene glycol) and poly(methyl acrylate)‐graft‐poly(ethylene glycol)

AbstractGraft copolymers consisting of amorphous main chain, poly(methyl methacrylate) (PMMA), or poly(methyl acrylate) (PMAc), and crystalline side chains, poly(ethylene glycol) (PEG), have been prepared by copolymerization of PEG macromonomers with methyl methacrylate or methyl acrylate (MMAxor MACx, respectively). Because of the compatibility of PMMA/PEG and PMAc/PEG, from small‐angle X‐ray scattering results, the main and side chains in graft copolymers were suggested to be homogeneous in the molten state. Differential scanning calorimetry (DSC) cooling scans revealed that PEG side chains for graft copolymers with large PEG fractions were crystallized when the sample was cooled, with a cooling rate of 10 °C/min. The spherulite pattern observed by a polarized optical microscope suggested the growth of PEG crystalline lamellae. Crystallization of PEG in MMAxwas more restrained than in MACx. From these results, we have concluded that the crystallization behavior of the grafted side chains is strongly influenced by the glass transition of a homogeneously molten sample as well as dilution of the crystallizable chains. Domain spacings for isothermally crystallized graft copolymers were described by interdigitating chain packing in crystalline–amorphous lamellar structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 79–86, 2005

Novel Alternating Fluorene-Based Conjugated Polymers Containing Oxadiazole Pendants with Various Terminal Groups

A series of soluble alternating fluorene-based copolymers containing symmetrical and asymmetrical 1,3,4-oxadiazole (OXD) pendants with various terminal groups are synthesized by the palladium-catalyzed Suzuki coupling reaction. These polymers possess higher glass transition temperatures than that of the analogous dialkoxy-substituted polymer (PFPOC6) consisting of the same backbone without OXD pendants. The photophysical and electrochemical properties of these polymers are affected by the polar effect (electron-withdrawing group, −CN, and electron-donating group, −R or −OR) and the size effect (the size of the grafted side chain) of the OXD pendants. Owing to the large steric hindrance of OXD pendants, the aggregation of these polymers in solids is reduced, which results in almost identical PL emissions in both solution and solid states. The bulky OXD pendants on the polymer side chains can provide the polymer films with lower HOMO and LUMO energy levels and better electron injection property. Since only one emission peak is observed in both PL and EL spectra of these polymers, it is evidenced that effective energy transfer from the OXD pendants to the conjugated polymer backbones has occurred, thus eliminating the light emission from the OXD pendants. These asymmetrical OXD-substituted polymers have higher quantum yields and less aggregation in the solid state than the symmetrical OXD-substituted polymers. The symmetrical OXD-substituted polymer (P1) has a longer PL emission wavelength than the asymmetrical OXD-substituted polymers (P2−P8), which may be due to the improvement of the coplanarity between the polymer backbone and the symmetrical OXD pendants and/or the introduction of two electron-withdrawing OXD pendants.

Synthesis and Single Molecule Force Spectroscopy of Graft Copolymers of Poly(2-hydroxyethyl methacrylate-g-ethylene glycol)

In this study, an end-functionalized graft copolymer, thiol-terminated poly(2-hydroxyethyl methacrylate-g-ethylene glycol) or SH-poly(HEMA-g-EG), was synthesized by the atom transfer radical polymerization (ATRP) method and then characterized by 1H nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and light scattering (LS). The polymer was covalently end-grafted to an Au substrate at low enough grafting densities to produce well-separated individual polymer “mushrooms” and single molecule force spectroscopy (SMFS) was then employed to measure the single polymer extensional elastic properties in phosphate buffered saline solution (PBS, ionic strength (IS) = 0.15 M, pH = 7.4) and deionized H2O (IS ∼ 6 × 10-5 M, pH = 5). In both solvents, the polymer behaved as an extensible freely jointed chain with a statistical segment length, a = 0.52 ± 0.09 nm, and a segment elasticity, ksegment = 10.5 ± 3.3 N/m, in PBS and a = 1.03 ± 0.01 nm and ksegment = 4.2 ± 0.5 N/m in H2O. Comparison to the known single molecule elasticity behavior for the PEG homopolymer suggests a smaller number and/or smaller magnitude of the noncovalent inter- and intramolecular interactions along the HEMA backbone and that even at this low PEG side chain grafting density, the side chains are still quite effective in causing local expansion of the PHEMA backbone by overcoming hydrophobic collapsing forces relative to the PHEMA homopolymer. Since the PEG chains are still well-solvated in PBS, one explanation for the small variation in nanomechanical properties with solvent is that in PBS the salt ions compete for and weaken the inter- and intramolecular H-bonding that does exist along the PHEMA backbone, causing a local contraction and an increased segmental stiffness due to the reduced noncovalent nature of the segments.

Metalization of polypropylene. I. Synthesis and melt free‐radical grafting of novel maleimides and methacrylates containing chelating moieties

AbstractSeveral chelating monomers with methacrylate and maleimide residues as polymerizable groups and diketone and aspartic acid residues as metal‐bonding groups were synthesized. A long‐chain aliphatic spacer was introduced to increase the solubility of the monomers in the polymer melt and to enhance the compatibility of grafted side chains and homopolymers with polypropylene (PP). PP was functionalized by melt free‐radical grafting, and some properties of the modified polymer were investigated. The grafting of a chelating methacrylic ester by injection molding afforded grafting yields of 30–50%. A comparison with products obtained by the grafting of commercially available acetoacetoxy methyl methacrylate showed the beneficial effect of the aliphatic spacer with respect to the grafting yield as well as the tensile strength and flexural modulus. The grafting of an aspartic acid based maleimide in an extruder afforded grafting yields of 80–95% and a significant increase in the surface wettability, as shown by contact‐angle measurements. A comparative study using samples obtained by the grafting of maleimidobenzoic acid indicated that the homogeneity‐increasing effect of the spacer was neutralized by the detrimental effect of the dicarboxylic chelating group. Nevertheless, the results showed that the maleimides were well suited for grafting by reactive extrusion because of their low susceptibility to homopolymerization under melt‐processing conditions. Preliminary metalization experiments showed the feasibility of plating without the use of corrosive etchants. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3400–3413, 2003

Densely grafted polyisocyanides synthesized by two types of polymerization techniques

AbstractA series of novel polyisocyanide‐graft‐polystyrenes and polyisocyanide‐graft‐[polystyrene‐block‐poly(butyl acrylate)]s were synthesized through the grafting‐through and grafting‐from routes with two types of living polymerization techniques: polymerization with the Pd–Pt μ‐ethynediyl dinuclear complex as the initiator and catalyst for the polyisocyanide backbone and atom transfer radical polymerization for the grafted side chain. Through the introduction of a chiral center at the side chain of the polyisocyanide backbone, helical grafted and graft block polyisocyanides were prepared through the grafting‐from method. All of the obtained polymers exhibited polydispersities in the range of 1.07–1.41. This might have been the first time grafted polyisocyanides were prepared, especially helical grafted polyisocyanides, through the operation of two living polymerization techniques. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1871–1880, 2003

Preparation of N-grafted polyanilines utilizing ring-opening copolymerization of epoxide : Tuning of solubility and optical and electrochemical properties of polyaniline

Polyanilines with various degrees of N-grafting have been synthesized by using ring-opening copolymerization of glycidyl phenyl ether (1,2-epoxy-3-phenoxypropane). The obtained polymer has good solubility in common organic solvents. Optical and thermal properties of the N-grafted polyanilines varying with the degree of the N-grafting and length of the graft side chain have been revealed. The polymer received electrochemical oxidation at about 0.40 V versus Ag +/Ag in a CH 3CN solution of 0.10 M LiBF 4.

Polymer Emulsion for Thermal Ink Jet System

Polymer emulsion is very useful for inkjet inks because it can treat media surface at the same time of printing and improve the print durability and then enlarge the application of inkjet printer. But for the thermal inkjet system, polymer emulsion is likely to make aggregates by heating of the ejection and make serious kogation on the heater. To avoid this thermal problem, heat stable polymer emulsion is necessary.In this paper, several kinds of polymer emulsion are investigated for thermal inkjet inks and low molecular polyester emulsion, polyacrylamide emulsion, and acrylic polymer emulsion with silicone graft side chain are found to show good heat stability for thermal inkjet systems. Especially, the introduction of silicone graft side chain improves the heat stability of the polymer emulsion with only 10% modification and is favorable for further polymer designing.

Ruthenium-Chelating Poly(heteroaryleneethynylene)s: Synthesis and Properties

A series of ruthenium(II)-chelating poly(heteroaryleneethynylene)s were synthesized by the palladium-catalyzed cross-coupling polycondensation of diethynylbenzenes and dibromobipyridine−Ru(II) chelates. The grafting of different alkoxy side chains including n-butoxy, (2-ethylhexyl)oxy, and n-octadecyloxy in the diethynylbenzene compounds enhances the solubility and processability of the new polymers. The same effect is attainable by tert-butyl substituents in the 2,2‘-bipyridine ligands. The UV/vis absorption showed a considerable red shift of the λmax from poly{bis(2,2‘-bipyridine)-[2,2‘-bipyridine-5,5‘-diylethynylene-(2,5-dialkoxy)ethylene]ruthenium(II) bis(hexafluorophosphate)} (5) to the 4,4‘-diylethynylene isomers 6, suggesting an increase in the electronic delocalization between the backbone and ruthenium(II) chelate. The polymers are good photoconducting materials (IPh = 3.7 × 10-12 A at 18 000 cm-1), exhibiting an oxidation potential of 1.24 V vs SCE. The polymers are thermostable and exhibit a go...

Synthesis and Properties of Novel Well-Defined Alternating PPE/PPV Copolymers

The polycondensation reactions of luminophoric dialdehydes 5 and bisphosphonates 3 provide a new type of π-conjugated polymers 7 with well-defined structure (—Ar—C≡C—Ar—C≡C—Ar—CH=CH—Ar— CH=CH—)n , which was confirmed by NMR, infrared and UV-Vis spectroscopy. High molecular weight (M̄w up to 500 000 g/mol), thermostable, soluble and transparent film-forming materials were obtained. The grafting of large alkoxy side chains enhances the solubility and processability of the new compounds. The incorporation of triple bonds into the PPV backbone increases the oxidation and reduction potentials, thus making these polymers potentially good electron-transporting materials if used in light-emissive-diode devices. The polymers are photoconductive and show very good photoluminescent properties in solution as well as in the solid state. Identical absorption (λmax,abs = 445 nm) and emission (λmax,em = 490 nm) behaviors were observed for all polymers in solution (CHCl3), resulting in a fluorescence quantum yield of 70%, but the photophysical behavior in solid state was side group dependent. Polymer 7ac shows a very large Stokes shift (137 nm) and lower fluorescence quantum yield (19%), whereas 7aa, 7bb and 7ab, consisting of side groups equal to or longer than O(CH2)11CH3 are characterized by smaller Stokes shifts (around 30 nm) and comparatively higher fluorescence quantum yields (34 to 44%).

Modification of lignin for the production of new compounded materials.

The cell walls of woody plants are compounded materials made by in situ polymerization of a polyphenolic matrix (lignin) into a web of fibers (cellulose), a process that is catalysed by polyphenoloxidases (laccases) or peroxidases. The first attempt to transform the basic strategy of this natural process for use in human craftsmanship was the ancient lacquer method. The sap of the lacquer tree (Rhus verniciflua) contains large amounts of a phenol (urushiol), a polysaccharide and the enzyme laccase. This oil-in-water emulsion solidifies in the presence of oxygen. The Chinese began using this phenomenon for the production of highly creative artwork more than 6,000 years ago. It was the first example of an isolated enzyme being used as a catalyst to create an artificial plastic compound. In order to apply this process to the production of products on an industrial scale, an inexpensive phenol must be used, which is transferred by an enzyme to active radicals that react with different components to form a compounded material. At present, the following approaches have been studied: (1) In situ polymerization of lignin for the production of particle boards. Adhesive cure is based on the oxidative polymerization of lignin using phenoloxidases (laccase) as radical donors. This lignin-based bio-adhesive can be applied under conventional pressing conditions. The resulting particle boards meet German performance standards. By this process, 80% of the petrochemical binders in the wood-composite industry can be replaced by materials from renewable resources. (2) Enzymatic copolymerization of lignin and alkenes. In the presence of organic hydroperoxides, laccase catalyses the reaction between lignin and olefins. Detailed studies on the reaction between lignin and acrylate monomers showed that chemo-enzymatic copolymerization offers the possibility to produce defined lignin-acrylate copolymers. The system allows control of the molecular weights of the products in a way that has not been possible with chemical catalysts. This is a novel attempt to enzymatically induce grafting of polymeric side chains onto the lignin backbone, and it enables the utilization of lignin as part of new engineering materials. (3) Enzymatic activation of the middle-lamella lignin of wood fibers for the production of wood composites. The incubation of wood fibers with a phenol oxidizing enzyme results in oxidative activation of the lignin crust on the fiber surface. When such fibers are pressed together, boards are obtained which meet the German standards for medium-density fiber boards (MDF). The fibers are bound together in a way that comes close to that by which wood fibers are bound together in naturally grown wood. This process will, for the first time, yield wood composites that are produced solely from naturally grown products without any addition of resins.

Aggregation behavior of proto-type amphiphilic copolymer brushes in aqueous solution

It is well known that comb copolymers with densely grafted side chains in a good solvent can adopt a worm-like cylindrical brush conformation, in which the side chains are stretched in the direction normal to the backbone owing to the excluded volume interaction. Polymerizations of macromonomers provide regular multi-branched polymers with dense branching. Since both degree of polymerization and the length of branches are varied, poly(macromonomer)s, often so-called “polymer brushes,” are interesting models for the study of the branched polymers [1–9]. We have reported the synthesis and dilutesolution properties of poly(diblock macromonomer)s: polystyrene-block-polyisoprene (PS-block-PI) [10] and PS-block-poly(2-vinylpyridine) (P2VP) diblock poly (macromonomer)s [11]. These types of poly(diblock macromonomer)s have the advantage of controlling the stiffness of the main chain parts by crosslinking inner PI or P2VP blocks. Free-radical copolymerization of binary macromonomers will form copolymers with not only combshaped but also hetero-armed structures. In this preparation process, the relevant copolymerization parameters are very important in determining the branch distribution in the resulting comb-shaped copolymers. Free-radical copolymerizations of binary vinylbenzylterminated PS and PI macromonomers were carried out in benzene, varying the molecular weight of the macromonomers [12]. The reactivity ratios of these systems were close to an azeotropic copolymerization, in the case of the same degree of polymerization (DP) for binary macromonomers. Subsequently, free-radical copolymerizations of vinylbenzyl-terminated PS (PSVM; M1) with maleate-terminated poly(ethylene oxide) (PEO-MA; M2) were carried out in benzene, in order to achieve alternative reactivity [13]. The reactivity ratios (r1 = 0.765 and r2 = 0.064) obtained for such binary macromonomer systems were different from the corresponding model system of styrene and maleic acid ethyl ester (r1 = 0.13 and r2 = 0.035) due to phase separation. More recently, free-radical copolymerizations of PS-VM (M1) with methacryloyl-terminated PEO (PEO-MC; M2) were carried out under various copolymerization conditions [14]. As a result, the reactivity ratios (r1 = 0.25 and r2 = 0.02) obtained for the binary copolymerization of PS-VM with PEO-MC/tin tetrachloride (SnCl4) complex showed strong alternation (Scheme 1). It was suggested the alternation results from homopolymerization of 1 : 1 complexes formed Scheme 1

Biodegradable Plastics from Cellulose

Brief history of the attempts trying to develop biodegradable plastics from cellulose acetates were reviewed in the first part. Then, two kinds of authors' trials were introduced. One of them is a plasticization trial for cellulose acetates (CAs) that is based on the reaction with dibasic acid anhydrides and monoepoxides during melt processing under practical process conditions. This reactive melt-processing method allowed the preparation of biodegradable cellulosic plastics with enough thermoplasticity and moldability. The biggest problem was the occurrence of external plasticizer's bleeding, which was found to be prevented by effective yield of grafting. Higher biodegradabilities have been found for the grafted CAs compared to the unmodified CAs. From the above trial, the amounts of grafting and the graft efficiency were intended to increase. As one of its extensions, a plasticization method for CA based on selective grafting of ϵ -caprolactone (CL) and lactide (LACD) has been developed. The selective-grafted products could be prepared by ring-opening polymerization in the melt state. By using adequate reaction conditions, the grafting reaction proceeded and completed rapidly (within 10–30 min). Transparent amorphous molding were obtainable. The fact that the formed graft side-chains contain a large amount of randomly polymerized parts explains the high thermoplasicity and amorphous nature of the grafted products.

Electron Beam Graft-Polymerization on Inert Polymer Membranes and Introduction of Thiol Group on the Grafted Side Chains.

Applying the electron beam-preirradiation method, glycidyl methacrylate (GMA) or its mixture with 2-hydroxyethyl methaclylate (HEMA) was grafted onto some inert polymer membranes such as polypropylene (PP), poly(vinylidene) fluoride (PVDF) and poly(tetrafluoroethylene)(PTFE). The epoxide rings of the graft chains were converted to chloride by reacting with HCl and then to -SH by reacting with NaSH. These membranes were analyzed by several methods and the metal ion sorption ability of the membranes was investigated. Consequently the following results were obtained; 1) PP and PVDF membranes could be easily grafted and the degree of grafting could be varied from a little % to approximately 1, 000% by changing the monomer concentration and the reaction time after EB-irradiation. In the case of PTFE membrane the degree of grafting was 40% even under the optimum condition. 2) The content of thiol group could be varied from 0.3 to 3.6mmol/g membrane. In spite of heterogeneous reaction the conversion efficiency of epoxide ring to -SH group was very high up to 66∼77% even under the mild condition such as at 323K. 3) The content of residual free-SH group in the NaSH-treated graft membranes was relatively low. It can be explained by the fact that the most of introduced -SH groups were combined to each other to form disulfide bonds by air oxidation. In contrast with these membranes, membranes grafted with a mixture of GMA/HEMA(45/55) possessed ca. 25mol% free -SH groups. 4) The -SH and -SS- introduced membranes showed selectively metal ion sorption ability, hence, extremely high sorption for Au ion.