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.     

Synthesis of polyvinyl acetate-graft-poly-2-oxazolines

Poly(vinyl acetate-co-vinyl chloroformate) ( 1 ) was synthesized via phosgenation of poly(vinyl acetate-co-vinyl alcohol). It was shown that ( 1 ) is capable of initiating the polymerization of 2-phenyl-2-oxazoline and 2-methyl-2-oxazoline, when the counter ion is exchanged using potassium iodide. Polyvinyl acetate-graft-poly-2-phenyl-2-oxazoline and polyvinyl acetate-graft-poly-2-methyl-2-oxazoline are obtained in the grafting reaction.     

Development of a new azido-oxazoline monomer for the preparation of amphiphilic graft copolymers by combination of cationic ring-opening polymerization and click chemistry

A new monomer (2-(5-azidopentyl)-2-oxazoline) bearing an azido group was synthesized. The cationic ring-opening copolymerization of this monomer with 2-methyl-2-oxazoline resulted in a well-defined linear polymer backbone with pendant azido groups. Alkynyl-poly(d,l-lactide) was grafted onto the azido groups of poly(oxazoline) via a Huisgen 1,3-dipolar cycloaddition reaction to give a novel amphiphilic graft copolymer [poly(2-methyl-2-oxazoline-co-2-pentyl-2-oxazoline)-g-poly(d,l-lactide)] (P[(MeOx-co-PentOx)-g-LA]). Different graft copolymers were prepared with PLA of different lengths. Preliminary results of the self-association of this copolymer in water indicated the formation of nanoparticles, which suggests this copolymer may have applications as vehicles for drug delivery.     

Miscibility of polysulfone and poly(ether sulfone) with tertiary amide polymers

The miscibility of polysulfone (PSf) and poly(ether sulfone) (PES) with three tertiary amide polymers has been studied. PES is miscible with poly(N-methyl-N-vinylacetamide) (PMVAc) and with poly(N,N-dimethylacrylamide) (PDMA) but not with poly(2-methyl-2-oxazoline) (PMOx). Miscible PES/PDMA blends show lower critical solution temperature behavior. However, PSf is immiscible with all the three tertiary amide polymers. Previous studies have shown that both PES and PSf are miscible with poly(N-vinyl-2-pyrrolidone). PES is also miscible with poly(2-ethyl-2-oxazoline) but PSf is not. Therefore, PES is more readily miscible with tertiary amide polymers as compared to PSf. Received: 23 October 1996/Revised: 11 November 1996/Accepted: 12 November 1996     

Synthesis of palladium clusters with surface initiator for polymerization of 2-methyl-2-oxazoline

Summary Palladium clusters were synthesized by reduction of palladium(II) acetate in the presence of a bipyridyl ligand (1) with an initiator for polymerization of 2-methyl-2-oxazoline. The 1-protected palladium clusters were soluble in CHCl₃ and CH₂Cl₂. The 1-protected palladium clusters were combined with 2-methyl-2-oxazoline in chloroform. After polymerization, the reacted bipyridyl ligand was removed from the palladium cluster by suspending the obtained palladium clusters with pyridine. The ¹H NMR measurement indicated that the reacted bipyridyl ligand was formed via surface polymerization of 2-methyl-2-oxazoline. Received: 19 April 2001/Accepted: 2 May 2001     

Novel aprotic polar polymers 2. Miscibility of aliphatic polysulfoxides

Summary Miscibility of aliphatic polysulfoxides (1, 2) with other commodity polymers was examined by comparing glass transition temperature(s) (T_gs) of the mixture of these polymers with T_gs of the original polymers by differential scanning calorimetry. It was found that the aliphatic polysulfoxides had good miscibility with poly(2-methyl-2-oxazoline) or/and poly(N-vinylpyrrolidone). Received: 25 December 1997/Revised version: 23 February 1998/Accepted: 25 February 1998     

Novel aprotic polar polymers 3. Synthesis and properties of poly(phenyl vinyl sulfoxide)

Summary Poly(phenyl vinyl sulfoxide) 1 was prepared by anionic polymerization and its properties as a polymer homolog of dimethyl sulfoxide (DMSO) were examined. Polysulfoxide 1 was found to have good miscibility with poly(vinyl acetate) as well as poly(2-methyl-2-oxazoline) and poly(N-vinylpyrrolidone) by comparing glass transition temperature(s) (T_gs) of the mixture of these polymers with T_gs of the original polymers by differential scanning calorimetry. Received: 4 March 1998/Accepted: 23 March 1998     

Synthesis of poly(N,N-dimethylcarbamoylmethylene) as a polymer homolog of N,N-dimethylacetamide

Summary A novel polymer homolog of N,N-dimethylacetamide (DMAc) having amide groups on all main chain carbons, poly(N,N-dimethylcarbamoylmethylene) 1, was prepared by heating poly(di-t-butyl fumarate) 2 at 180 °C for 2 hours followed by treatment with hexamethylphosphoramide at 180 °C for 5 hours. The structure of the obtained polymer 1 was confirmed by ¹H-, ¹³C-NMR and IR spectroscopy. The polymer 1 actually showed the properties based on its repeating structures. 1 had the amphiphilicity and was soluble both in protic and aprotic solvents. Furthermore, 1 showed the miscibility with commodity polymers such as poly(N-vinylpyrrolidone), poly(vinyl alcohol) and poly(vinyl chloride). In comparison with another polymer homolog of DMAc, poly(2-methyl-2-oxazoline), the polymer 1 exhibited better miscibility with poly(N-vinylpyrrolidone). Received: 24 June 1999/Accepted: 19 July 1999     

Miscibility of conductive blends of poly(o-anisidine) with poly(2-alkyl-2-oxazoline)s

HCl-doped poly(o-anisidine) (PANIS–HCl) and undoped poly(o-anisidine) (PANIS-base) were blended with poly(2-methyl-2-oxazoline) (PMOx) or poly(2-ethyl-2-oxazoline) (PEOx) by solution casting from dimethyl sulfoxide. Blends containing 50 wt % or less of PANIS–HCl or PANIS-base were flexible and homogeneous. The glass transition temperature of the blend continuously shifted away from that of PMOx or PEOx with increasing PANIS–HCl or PANIS-base content, indicating miscibility. The shift in the T_g value was larger for the PMOx blend than for the corresponding PEOx blend, suggesting a stronger interpolymer interaction in the former blend. Fourier transform infrared spectroscopic studies indicated the presence of specific interactions in the blends as evidenced by the changes of C=O and NH bands. Blends containing 50 wt % of PANIS–HCl showed conductivity of about 10^-4 S/cm. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:391–397, 1997     

Peptide-Mimicking Poly(2-oxazoline)s Displaying Potent Antimicrobial Properties

Poly(2-oxazoline)s have excellent biocompatibility and have been used as FDA-approved indirect food additives. The inert property of the hydrophilic poly(2-oxazoline)s suggests them as promising substitutes for poly(ethylene glycol) (PEG) in various applications such as anti-biofouling agents. It was recently reported that poly(2-oxazoline)s themselves have antimicrobial properties as synthetic mimics of host defense peptides. These studies revealed the bioactive properties of poly(2-oxazoline)s as a new class of functional peptide mimics, by mimicking host defense peptides to display potent and selective antimicrobial activities against methicillin-resistant Staphylococcus aureus both in vitro and in vivo, without concerns about antimicrobial resistance. The high structural diversity, facile synthesis, and potent and tunable antimicrobial properties underscore the great potential of poly(2-oxazoline)s as a class of novel antimicrobial agents in dealing with drug-resistant microbial infections and antimicrobial resistance.     

Miscibility and interpolymer complexation of poly(2-methyl-2-oxazoline) with hydroxyl-containing polymers

Poly(2-methyl-2-oxazoline) (PMOx) was found to be miscible with poly (styrene-coallyl alcohol), poly(hydroxyether of bisphenol-A), poly (2-hydroxypropyl methacrylate) and poly(p-vinylphenol) (PVPh), when cast from N,N-dimethylformamide solutions and to form interpolymer complexes with PVPh in methanol solutions. The hydrogen bonding interactions between PMOx and hydroxyl-containing polymers were studied by infrared spectroscopy and compared with the corresponding blends of poly(2-ethyl-2-oxazoline) (PEOx). Except with phenoxy, PMOx interacts more strongly with hydroxyl-containing polymers than PEOx does.     

Miscible blends of conductive polyaniline with tertiary amide polymers

Polyaniline (PANI) was doped with p-phenolsulfonic acid (PSA) or 5-sulfosalicylic acid (SSA). The PANI salts were blended with poly(N-vinyl-2-pyrrolidone), poly(N-methyl-N-vinylacetamide), poly(N,N-dimethylacrylamide), or poly(2-methyl-2-oxazoline) by solution casting from dimethyl sulfoxide. Blends containing up to 50% by weight of PANI salt were homogeneous and each exhibited a single glass transition temperature, indicating miscibility. Fourier transform infrared spectroscopic studies indicated that the carbonyl groups of the tertiary amide polymers interacted with the PANI salt as evidenced by the development of a shoulder at a lower frequency in the carbonyl stretching band. Electrical conductivities of the blends are in the range 10⁻⁵ to 10⁻³ S/cm, depending on the blend composition. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1839–1844, 1998     

Synthesis and properties of poly(vinyl chloride-g-2-methyl-2-oxazoline)

Summary Poly(vinyl chloride-g-2-methyl-2-oxazoline) copolymers were prepared by grafting from the allyl chloride sites of PVC with KI or AgOSO₃CF₃ as coinitiators. Use of AgOSO₃CF₃ led to higher grafting efficiencies and higher contents of poly(2-methyl-2-oxazoline) in the graft copolymers. DTA analyses of the P(VC-g-Me-Oxz) identified the thermal transitions of this copolymer; TGA analyses showed that the graft copolymers were less thermally stable than the constituent homopolymers. Unlike blends of P(Me-Oxz) and PVC, the graft copolymers could be molded easily; the graft materials exhibited greater flexural moduli but lower HDT's than PVC.     

Star-Shaped Poly(2-methyl-2-oxazoline) Using by Reactive Bromoethyl Group Modified Calix[4]resorcinarene as a Macrocyclic Initiator

Summary Star-shaped poly(2-methyl-2-oxazoline) (POZO) was prepared by ring-opening polymerization of 2-methyl-2-oxazoline from a novel calix[4]resorcinarene with reactive bromoethyl groups (8Br-CX4) as an initiator. The core-first method, which uses an active multifunctional core to initiate growth of polymer chains, was applied for synthesis of star-shaped POZO based on 8Br-CX4. The obtained star-shaped POZOs were characterized by ¹H NMR, ¹³C NMR, FT-IR and DSC. From ¹H NMR, DLS and fluorescence measurements, the star-shaped POZOs formed nanometer scale micelles in aqueous media composed of hydrophobic calix[4]resorcinarene moieties and hydrophilic POZO groups.     

New telechelic polymers and sequential copolymers by polyfunctional initiator-transfer agents (inifers)

Summary Linear and three-arm star tosyl-telechelic polyisobutylenes (i.e., PIB's carrying two and three p-toluene-sulfonic acid ester end groups, respectively) have been synthesized and characterized by a variety of techniques. Subsequently these prepolymers were used as macroinitiators for the ring opening polymerization of 2-methyl-2-oxazoline leading to linear poly(N-acetylethyleneimine-b-isobutylene-b-N-acetylethyleneimine) and three-arm star poly(N-acetylethyleneimine-b-isobutylene). High yields (78–98%) and blocking efficiencies (70–80%) have been obtained. The absence of free polyisobutylene in the product indicates highly efficient initiation of 2-methyl-2-oxazoline polymerization by the tosyl-telechelic polyisobutylene. The less than 100% blocking efficiencies are probably due to chain transfer to 2-methyl-2-oxazoline. Hydrolysis of these block copolymers yielded poly(ethyleneimine-b-isobutylenes).Present address: Department of Macromolecular Science, Case Western Reserve University, Cleveland, Ohio 44106.Present address: Central Research Institute for Chemistry, Hungarian Academy of Sciences, Budapest, Hungary.     

Organic-inorganic polymer hybrids using octasilsesquioxanes with hydroxyl groups

Summary Polymer hybrids were prepared by three kinds of octasilsesquioxanes having hydroxyl groups and organic polymers such as poly(2-methyl-2-oxazoline) (POZO), poly(N-vinylpyrrolidone) (PVP), and poly(N,N-dimethylacrylamide) (PDMAAm) using hydrogen bonding interaction. The obtained homogeneous and transparent hybrid films could be dissolved in solvents and cast again without any separation. It was found that the high homogeneity of polymer hybrids was the result of hydrogen bonding interaction between octasilsesquioxanes and organic polymers from the carbonyl stretching shifts in IR measurement. Also, the influence of flexibility of eight arms bound to silica-like core on the homogeneity of polymer hybrids was examined. Received: 8 May 2001/Accepted: 24 May 2001     

Triblock copolymers of 2-methyl-2-oxazoline and poly(ethyleneglycoladipate)

Summary 2-methyl-2-oxazoline was polymerized by using poly(ethyleneglycoladipate) having tosylate end groups as an initiator. Polymerization was carried in bulk, and ABA type block copolymers were obtained containing poly(N-acetylethylenimine) as A block (hard part) and poly(ethyleneglycoladlpate) as B block (soft part).     

Synthesis of fatty 2-oxazolines from fatty methyl 2,3-epoxy ester

Reaction of methyltrans-2,3-epoxyhexadecanoate (I) with benzonitrile in presence of boron trifluoride-etherate (BF₃-etherate) as catalyst has yieldedcis-2-phenyl-4-tridecyl-5-carbomethoxy-2-oxazoline (II), methyl 2-hydroxy-3-benzamidohexadecanoate (IV) and methyl 2,3-dihydroxyhexadecanoate (III). On the other hand, reactions of I with acetonitrile and acrylonitrile have resulted in the formation of their corresponding hydroxyamides, methyl 2-hydroxy-3-acetamidohexadecanoate (VI) and methyl 2-hydroxy-3-acryloamido hexadecanoate (VII), respectively, along with the product (III) only. Pyrolysis of hydroxyamides (IV), (VI) and (VII) afforded their corresponding 2-oxazolines,cis-2-phenyl-4-tridecyl-5-carboxy-2-oxazoline (V),cis-2-methyl-4-tridecyl-5-carboxy-2-oxazoline (VIII) andcis-2-vinyl-4-tridecyl-5-carboxy-2-oxazoline (IX), respectively, in good yields. The products have been characterized with the help of spectral and microanalyses. Presented at the 4th Annual Convention of the Indian Council of Chemists held in December 1984 at Gorakhpur University, India.     

Thermal degradation of copolymers based on 2-substituted oxazolines and β-methylhydrogenitaconate

Summary The thermal stabilities of poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline) and poly(-methylhydrogenitaconate-co-2-ethyl-2-oxazoline) obtained by spontaneous copolymerization have been studied by programmed thermogravimetric analysis over the temperature range from 293 K to 773 K under a flow of nitrogen. Most of the copolymers do not show weight loss until 473 K and they degrade in one step. The kinetic parameters Ea, n and A were obtained following one method of thermogravimetric analysis. The reaction order for all copolymers was 1.0. The poly(-methylhydrogenitaconate-co-2-methyl-2-oxazoline)s were the most thermostable copolymers.     

Gelation of telechelic trimethoxysilyl-terminated polyoxazolines

Summary Telechelic bifunctional polyoxazoline (poly(N-acetylethylenimine), PAEI) was prepared by ring-opening polymerization of 2-methyl-2-oxazoline (1) in the presence ofp-(,-dibromo)xylene (2) as an initiator. The terminal propagating ends of this polyoxazoline were reacted with 3-aminopropyltrimethoxysilane (4) to give telechelic trimethoxysilyl-terminated polyoxazoline (5). Gelation of this telechelic polymer was carried out by hydrolysis and condensation of alkoxysilyl groups. By this method, the PAEI gels were obtained in good yields, and their degrees of swelling in the solvent could be controlled successfully by the feed ratios of the initiator to the monomer in the stage of the polymerization of 2-methyl-2-oxazoline. However, the cross-linked products were not stable and gradually dissolved in water. The gels were also swollen inN,N-dimethyl-formamide (DMF). The degrees of swelling of these gels were thus measured in DMF.