Functional polymers

Summary Polymeric antioxidants prepared from 2,6-di-tertiary-butyl-4-vinyl (4-lsopropenyl)phenol and butadiene or isoprene, and their hydrogenated products (6-8 mol % of phenolic AO in the polymer) were tested by oxygen uptake studies for their effectiveness as antioxidants for polyolefins and polydienes. The polymeric antioxidants seem to be slightly less effective in short-term protection against oxidation at 150° C as compared to low molecular weight antioxidants, but more effective in long-term protection of the polymer samples at a level of 0.1 weight percent.Part 43: P. Grosso, O. Vogl: J. Macromol. Sci. Chem., in pressNow Chemical Company, Midland, MI 48674, USATo whom all correspondence should be addressed: Herman F. Mark Professor of Polymer Science, Polytechnic Institute of New York, Brooklyn, NY 11201, USA     

Functional polymers

Selected 10-undecenoic acid esters were prepared from 10-undecenoic acid and four phenolic ultraviolet stabilizers: (1) 2(2-hydroxy-4-undecenoxyphenyl) 2H-benzotriazole, (2) 2(2,6-dihydroxy-4-undecenoxyphenyl)2H-benzotriazole, (3) 2(2-hydroxy-4-undecenoxyphenyl)1,3-2H-dibenzotriazole, and (4) 2(2,6-dihydroxy-4-undecenoxyphenyl)1,3-2H-dibenzotriazole. The esterification was carried out by allowing 10-undecenoic acid to react with N,N-carbonyldiimide followed by the addition of the phenol. The polymerizable ultraviolet absorbers were characterized.Part XXXIII: F. Xi, W. Bassett, Jr., and O. Vogl, Polymer Bulletin 11(4), 329 (1984).     

Functional polymers

2-(2,4-Dihydroxyphenyl)2H-4-methoxybenzotriazole was treated with acryloyl or methacryloyl chloride and gave 2[2-hydroxy-4-acryloxy(methacryloxy)phenyl]2H-4-methoxybenzotriazole. The two monomers were homo-polymerized and copolymerized with styrene, methyl methacrylate and n-butyl acrylate with azobisisotutyronibrile as the initiator. The monomers, homopolymers and copolymers were characterized.Functional Polymers XXXII: F. Xi, W. Bassett, Jr., and O. Vogl, J. Polym. Sci., Polym. Chem. Ed., in press.     

Functional polymers

Acrylates and methacrylates of 1,3(2,4-dihydroxyphenyl)-di(2H-benzotriazole) and 1,3(2,4,6-trihydroxyphenyl)-di(2H-benzotriazole) have been prepared by treating acrylic acid or methacrylic acid with N,N-dicyclohexyl carbodiimide and then allowing this mixture to react with the phenolic ultraviolet absorbers to give 1,3[2-hydroxy-4-acryloxy(methacryloxy)phenyl]-di(2H-benzotriazole) and 1,3[2,6-dihydroxy-4-acryloxy(methacryloxy)phenyl]-di(2H-benzotriazole). The yield of the esters was from 10 to 30%; they were characterized by their infrared, ¹H, and ¹³C NMR spectra; their polymerizability was demonstrated. The compounds had X of 330 to 335 nm with extinction coefficients ranging from 3.0 to 3.5×10⁴ L/mol·cm.     

Functional polymers for photovoltaic devices

Solar cells based on functional copolymers were considered as promising devices and can be used to solve the intractable energy crisis for humankind. In this review, several key factors in molecular structures and morphologies which may depress the power conversion efficiency of devices are discussed first. Moreover, we concentrate on the molecular design strategies which can be applied in synthesizing functional polymers with appropriate band gap energy, prolonged exciton diffusion distance, good charge carrier transportations, as well as suitable self-assembly microphase morphologies in solid state. Once these design strategies are selectively combined, polymer solar cells with optimized performance can be approached.     

Functional biomedical polymers for corneal regenerative medicine

Recent progress in biomedical polymer science has greatly contributed to rapid development of corneal regenerative medicine. In the past decades, scientists have achieved several major breakthroughs in corneal tissue reconstruction. Studies regarding the findings of core-and-skirt keratoprostheses for visual rehabilitation, biosynthetic tissue replacements for corneal transplantation, and thermo-responsive cell-detachable substrates for corneal cell sheet engineering have been reported by several groups of investigators. This brief overview focuses on the contributions of functional polymers in the applications of corneal regenerative medicine. The keratoprosthetic devices developed by our group using heterobifunctional silicone rubber membranes grafted with different bioactive functional groups showed promising results in animal studies. In addition, the fabrication and transplantation of bioengineered human corneal endothelial cell sheets by utilizing the functional biomedical polymers such as poly(N-isopropylacrylamide) and gelatin are discussed, especially for the significance of gelatin in the development of a potential intraocular delivery system for cell sheet grafts.     

Functional polymers and sequential copolymers by phase transfer catalysis

Summary Kinetic analysis of the cationic polymerization of 5-methyl-2-oxazoline (5-MeOZO) was performed with methyl tosylate(MeOTs) and methyl iodide(MeI) initiators by using ¹H NMR spectroscopy. With MeOTs the polymerization of 5-MeOZO proceeded through oxazolinium tosylate species 3 and 4 and the rate constant of propagation (k_p) was determined. With MeI, on the other hand, the propagating ends are present in equilibrium between alkyl iodide (covalent) species 7, 9 and 11 and oxazolinium(ionic) species 6, 8 and 10. Two model reactions enabled to determine the equilibrium constant (K) of 6/7 and to evaluate the reactivity of covalent species 9 (reflected by k_p(c)) and of ionic species 8 (reflected by k_p(i)). Both species 8 and 9 propagate concurrently and contribute to the whole propagation at comparative extents.     

Functional polymers and sequential copolymers by phase transfer catalysis

Summary Two new synthetic methods for the preparation of functional polymers containing 2-oxazoline pendant groups are presented. The first one consists on the phase transfer catalyzed etherification of 2-(p-hydroxyphenyl)-2-oxazoline with a mixture of m- and p-chloromethylstyrene to provide, after separation, m- and p-vinylbenzyl ethers of 2-(p-hydroxyphenyl)-2-oxazoline. Both monomers can be polymerized by a radical mechanism to provide polystyrene containing 2-oxazoline pendant groups. The second method represents a phase transfer catalyzed etherification of a poly(2,6-dimethyl-1,4-phenylene oxide) containing pendant bromomethyl groups with 2-(p-hydroxyphenyl)-2-oxazoline. Incomplete etherification of the bromobenzyl groups in this case, leads to the first example of a functional polymer containing not only cationically polymerizable heterocycles, but also their own cationic initiator as pendant groups.     

Functional polymers and sequential copolymers by phase transfer catalysis

Summary Poly(epichlorohydrin) (PECH) containing pendant mesogenic units separated from the polymer main chain through spacers of zero to ten methylene units were synthesized and characterized. The synthetic pathway used for the chemical modification of PECH involved the phase transfer catalyzed etherification and esterification of the chloromethyl groups with sodium 4-methoxy-4-biphenoxide and potassium -(4-methoxy-4-oxybiphenyl)alkanoates. All the resulting polymers, including that with no spacer, present thermotropic liquid crystalline mesomorphism.Part 29 in this series: C. Pugh and V. Percec, Polym. Bull., preceding paper     

Functional monomers and polymers, 98. Asymmetric induction by chiral polymers containing bornyl groups

In order to determine the catalytic ability of the polymers containing chiral bornyl groups to the asymmetric induction, the asymmetric addition reaction of dodecanethiol to isopropenyl methyl ketone was studied using synthetic chiral polymers having pendant bornyl groups, in comparison with the case of using a monomeric model compound, i.e. d-bornyl acetate, and also poly(methyl methacrylate). It was found that the polymers having chiral borynl groups were effective for the asymmetric induction, and the optical yield depended on the bornyl group content in the polymers.     

Functional water-insoluble polymers with ability to remove arsenic(V)

Three resins were synthesized through radical polymerization: poly[(ar-vinylbenzyl)trimethylammonium chloride] P(VBTA), poly[(ar-vinylbenzyl)trimethylammonium chloride-co-acryloylmorpholine] P(VBTA-co-AM), and poly[(2-acryloyloxy) ethyltrimethylammonium chloride-co-acryloylmorpholine]. The removal capacity for arsenic under different conditions was studied and compared with a commercial resin Amberlite IRA 400-Cl. The arsenic sorption capacity of the resins at the optimum pH showed the following order: Amberlite 95.5% (27.1 mg/g, 0.36 mmol/g), P(VBTA) 92.6% (16.3 mg/g, 0.22 mol/g), P(VBT-co-AM) 90.4% (21.5 mg/g, 0.29 mmol/g), and P(AETA-co-AM) 87.3% (21.7 mmg/g, 0.29 mmol/g).     

Functional monomers and polymers, 74. Physico-chemical study on the chitosan-iodine complexes

The adsorption of iodine on chitosan was studied by physico-chemical methods. The scanning electron micrograph measurements of chitosan-iodine adducts showed that iodine molecules were adsorbed uniformly on the chitosan film when the film was treated with aqueous iodine-potassium iodide solution. The thermogravimetric analysis of the adducts revealed that the loss in weight began at about 190°C, and that iodine molecules were thus well-complexed with chitosan. It was also found that the IR spectra of the chitosan films showed the amide I and amide II bands shifted to lower frequencies due to the iodine adsorption. The X-ray diffractometry of these adducts was further carried out, and it was found that the iodine adsorbed chitosan showed no crystalline pattern, different from that of the original chitosan which showed crystallinity in some extent. The chitosan recovered after desorbing iodine by immersion in aqueous sodium thiosulfate solution was amorphous.     

Functional derivatives of (bi)phenyl-substituted carbazoles as building blocks for electro-active polymers

(Bi)phenyl-substituted carbazoles containing reactive functional groups were synthesized by the multi-step synthetic rout. The monomers were examined by various techniques including thermogravimetry, differential scanning calorimetry, UV and fluorescence spectrometry as well as electron photoemission technique. These derivatives were also tested as hole transporting materials in bilayer OLEDs with Alq₃ as the emitter. The devices exhibited promising overall performance with a turn-on voltage of ～3 V, a maximal photometric efficiency of 5.1 cd/A and maximum brightness of 12,200–15,600 cd/m².     

Functional monomers and polymers, 85. On the adsorption of bromine onto chitosan

The adsorption of bromine onto powdery chitin, chitosan and cellulose was studied in an aqueous bromine-potassium bromide solution at 30°C. Chitosan was found to show an excellent ability of adsorbing bromine as well as iodine. The chitosan film also exhibited high ability of adsorbing bromine both in methanol and in aqueous potassium bromide solutions.     

Functional monomers and polymers. LXX. On the adsorption of iodine onto chitosan

The ability of adsorbing iodine in different organic solutions by chitosan was studied by sorption isotherm measurements. The ability was found to be larger in polar solvents than in nonpolar solvents. The form of the chitosan samples, such as film, powder, and flake, had no influence on the adsorption behavior. On the other hand, chitin had only small adsorbing ability of iodine. It is concluded that the adsorption of iodine is caused by charge—transfer complexes between aminogroups of chitosan and iodine molecules, but their structure differs from that of inclusion compounds as seen in amylose–iodine complexes. The adsorption was also studied on chitosan films with different degrees of acetylation.     

Functional monomers and polymers, 116. Asymmetric addition of n-butyllithium to aldehydes by chiral polymers and related compounds containing dimethylamino bornanol moieties

Asymmetric addition reaction of n-butyllithium to aldehydes was studied by using chiral polystyrene derivatives and chiral low molecular model compounds, both of which were derived from cis,endo-3-dimethylamino-2-hydroxybornane. The higher optical yields were achieved by using low molecular model compounds, and particularly the highest value was obtained in the case when ether was used as the solvent. The effect of reaction temperature, sort of the solvents and the molar ratio of the reagent to aldehyde on the asymmetric addition was also discussed.     

Functional metal-porphyrazine derivatives and their polymers, 10. Secondary fuel cells based on oxygen reduction on platinum electrode modified by polymers and metal-phthalocyanines

Secondary fuel cells based on oxygen reduction of platinum electrode modified by polymers and metal-phthalocyanine (Mt = Fe(III), Co(II), Ni(II), and Cu(II)) were studied. The discharge curves for the platinum electrode modified by poly(2-vinylpyridine) (or polystyrene) and Co-phthalocyanine in 30% KOH aqueous solution, for a 30 min charge at 500 μA, followed by a 100 μA discharge showed a stable plateau at about ?0.24 V SCE (Saturated Calomel Electrode). The open circuit voltage (vs. Zn) of the cell was 1.2 V, and the discharge capacity was of 46 A · h/kg. For this battery there was no significant decay in its characteristics after more than 30 charge-discharge cycles. In Mt-phthalocyanines, the values decreased in the order of Co(II) > Fe(III) > > Cu(II) > Ni(II). From a cyclic voltammogram for the electrode modified by the polymer and Co-Pc, the cathodic reactions were discussed.     

Functional water‐soluble polymers: polymer–metal ion removal and biocide properties

Water‐soluble polymers have attracted much interest due to their potential applications in environmental protection engineering to remove harmful pollutants and in biomedicine in the areas of tissue engineering, within‐body implants or other medical devices, artificial organ prostheses, ophthalmology, dentistry, bone repair, and so on. In this review, particular emphasis is given to the ability of water‐soluble polymers with amine, amide, carboxylic acid, hydroxyl and sulfonic acid functional groups to remove metal ions by means of the liquid‐phase polymer‐based retention (LPR) technique that combines the use of water‐soluble polymers and ultrafiltration membranes. The second part is dedicated to showing the potential application of functional water‐soluble polymers and their polymer–metal complexes as biocides for various bacteria. These polymers and polymer–metal complexes show an efficient bactericide activity, especially to Gram‐negative bacteria, Staphylococcus aureus reaching concentrations lower than 4 µg mL^?1. This activity depends on polymer size, type of metal ion, contact time and concentration of polymer and metal ion. The discussion reveals that in the case of the LPR process the efficiency of metal ion removal depends strongly on the type of polymer functional group and the feed pH value. In general, two mechanisms of ion entrapment are suggested: complex formation and electrostatic interaction. In the case of the medical use of water‐soluble polymers and their complexes with metal ions, the review documents the unique bactericide properties of the investigated species. The polymer‐metal ion complexes show a reduced genotoxic activity compared with free metal ions. Copyright © 2009 Society of Chemical Industry