Polymeric schiff base chelates and their precursors

Summary Covalently polymer bound Co(salen) 6a-c was synthesized starting from two macroporous resins 2a,b and a linear polystyrene 2c. Reaction of 2a-c with 5-chloromethylsalicylaldehyde to 3a-c, then with 1,2-diaminoethane to 4a-c and then with salicylaldehyde led to the metal free ligands 5a-c which could be metallized to 6a-c.     

Living carbocationic polymerization of isobutylene and synthesis of ABA block copolymers by conventional laboratory techniques

Summary Living polymerization of isobutylene (IB) and subsequent controlled synthesis of ABA block copolymers, such as poly(styrene-b-isobutylene-b-styrene) (PSt-PIB-PSt) and poly(p-methylstyrene-b-isobutylene-b-p-methylstyrene) (PpMeSt-PIB-PpMeSt), have been carried out by a simple and inexpensive conventional laboratory technique. The homo- and block copolymers obtained by using this technique have exhibited excellent molecular weight control and low polydispersity indexes. The living nature of IB polymerization has been demonstrated by the incremental monomer addition (IMA) method with the dicumyl methyl ether (DiCumOMe)/TiCl₄ initiating system in the presence of 2,5-di-tert-butylpyridine (DtBP) proton trap. PSt-PIB-PSt and PpMeSt-PIB-PpMeSt block copolymers have been synthesized by sequential monomer addition: first living difunctional polyisobutylene (PIB) midsegment was prepared by difunctional initiator, then the second monomer was added to the charge. High blocking efficiencies and desired block copolymer structures have been obtained.     

Behavior of deoxophostones family as nucleophilic monomers in no-catalyst copolymerization

Summary Deoxophostone family(2-phenyl-1,2-oxaphospholane1a, 2-phenyl-1,2-oxaphosphorlane1b, and 2-phenyl-1,2-thiaphospholane1c) copolymerized with acrylic acid without catalyst to produce the corresponding copolymers. The polymerization proceeded via a cyclic acyloxyphosphorane to produce poly-(phosphine oxide — ester)3a(or3b) from1a(or1b) and poly(phosphine oxide — thiolester)3c from1c, respectively, with acrylic acid. It is of interest that the copolymer from1c with acrylic acid was not poly(phosphine sulfide — ester)4 but3c. The reactions of1a or1b with pyruvic acid or 1,3-propane sultone were also investigated.The present authors dedicate this paper to the late Mr. Ken Mizuno.     

Synthesis and characterization of amphiphilic polyisobutylene/poly(ethylene glycol) di- and triblock copolymers

Summary Di- and triblock copolymers of polyisobutylene PIB and poly(ethylene glycol) PEG have been prepared and characterized. The syntheses involved the capping with tolylene 2,4-diisocyanate TDI various molecular weight -phenyl--(p-phenol) polyisobutylenes C₆H₅-PIB-C₆H₄OH and ,-di-(p-phenol)polyisobutylenes HOC₆H₄-PIB-C₆H₄OH, or commercially available mono- and di-hydroxyl-terminated PEGs. In this manner a series of PIB-b-PEG diblock copolymers, and PEG-b-PIB-b-PEG and PIB-b-PEG-b-PIB triblock copolymers have been obtained. The complete removal of the prepolymers from these amphiphilic sequential copolymers by conventional solvent extraction techniques could not be achieved because of the very high emulsifying action of the latters. In contrast, satisfactory separation was obtained by column chromatography using mixed (polar/nonpolar) eluents. The blocking efficiencies and composition of the block copolymers have been determined.Part XL V of the Series on New Telechelic Polymers and Sequential Copolymers by Polyfunctional Initiator-Transfer Agents (Inifers).     

Cationic ring-opening polymerization of spirophosphorane, 5-phenyl-1,4,6,9-tetraoxa-5-phosphaspiro[4,4]nonane

Summary This paper reports new cationic ring-opening polymerization of a spirophosphorane, 5-phenyl-1, 4, 6, 9-tetraoxa-5-phosphaspiro (4, 4) nonane, 1. The polymerization of 1. was induced by cationic initiators such as methyl trifluoromethanesulfonate (MeOTf), BF₃·OEt₂, and Et₃O⁺-BF₄ ^– to give polymer 2 consisting of two different units, 2a and 2b. During the reaction cyclic phosphonate 3 and 1,4-dioxane were simultaneously produced. The formation of unit 2b is considered to be due mainly to the cationic ring-opening polymerization of 3.     

Polymeric Schiff's base chelates and their precursors

Summary Various divinyl-Schiff's base ligands 3 were synthesized from 2-hydroxy-5-vinylbenzaldehyde (2) and diamines. Copolymerization of 3 with styrene directly leads to covalently polymer bound ligands 4. Introduction of Co(II) resulted in the formation of the chelates 6. Covalently polymer bound chelates show high activity for the reversible binding of dioxygen under formation of mononuclear superoxo complexes. The chelates exhibit good activities for the oxidation of 2,6-di-tert-butylphenol (9).Part 5: Ref. 1).     

Polymeric schiff's base chelates and their precursors 8a), some cobalt chelates as catalysts for the isomerization of quadrycyclane to norbornadiene

Summary Starting with Z-2, 3-diamino-2-butenedinitrile as diamine component the synthesis of the low molecular N,N,O,O-chelate 3.Co and its ligand 3 is optimized. An easy synthesis of the chelate 8.Co covalently bound on macroreticular resins is presented. The chelates 8.Co are the most active heterogenous catalysts for the valence isomerization of quadricyclane to norbornadiene today.     

Cationic polymerization of selected α- and β-substituted vinyl ethers

Summary The cationic polymerization of various α- and β-substituted vinyl ethers, initiated by 1-iodo-1-(2-methylpropyloxy)ethane 1 and tetrabuty lammonium perchlorate (TBAP) was investigated. The polymerization of 2,3-dihydrofuran (DHF, 3a) in CH₂Cl₂ at -40°C proceeds via opening of the ethylenic double bond and yields polymers with narrow molar mass distributions and high glass transitions. The number average of molar mass increased linearly with conversion. Under these conditions, a controlled polymerization of two propenyl ethers (1-ethoxypropene 2a and 2-methoxypropene 2b) and two other cyclic unsaturated ethers (3,4-dihydro-2H-pyran 3b and 5-methyl-2,3-dihydrofuran 3c) could not be achieved. Either transfer reactions or the decomposition of 1 prevented the formation of high molar mass polymers of these vinyl ethers.     

Polymeric bound porphyrines and their precursors

Summary The solid state synthesis of a monosubstituted phthalocyanine 6 is described. 4-(4-Hydroxyphenoxy)-1,2-benzenedicarbonitrile is polymer bound to a chloromethylated macroreticular polystyrene, yielding polymer 3. Reaction of 3 with 4-phenoxy-1,2-benzenedicarbonitrile in the presence of zinc salt results in the formation of covalently bound polymeric phthalocyanine 5. 6 is obtained by cleavage with HBr/acetic acid.Part 1: Ref. 1     

Polyisobutylene-containing block polymers by sequential monomer addition

Novel poly(acenaphtylene-b-isobutylene-b-acenaphtylene) (PAc-PIB-PAc) triblock copolymers exhibiting thermoplastic elastomer (TPE) properties have been prepared. The synthesis involved the addition of acenaphtylene (Ac) to living polyisobutylene dications (PIB) obtained by living isobutylene (IB) polymerization induced by the dicumyl methyl ether (DiCumOMe)/TiCl₄ initiating system at-80°C. The triblocks contain very short polyacenaphtylene (PAc) blocks (M_n9,000) and consequently yield very soft, low modulus TPEs. Efforts to develop conditions for the living carbocationic polymerization (LCPzn) of Ac have failed.For Part VIII of this subseries see J. P. Kennedy, S. Midha, B. Keszler: Macromolecules (in press)     

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.     

Alkyloxy-substituted liquid-crystalline aromatic copolyesters

Summary The synthesis and characterization of main chain liquid crystalline polyesters arising from 2,5-bispentyloxy substituted terephthalic aicd (3) and aromotic diols are described. 3 was prepared from diethyl 2,5-dihydroxyterephthalate and 1-bromopentane. The polyesters were prepared from 4,4-dihydroxybiphenyl (5), hydroquinone (6), 2,5-dimethyl hydroquinone (8) and the substituted terephthaloyl dichloride (4) in 1,1,2,2-terachloroethane. Their structures were characterized by ¹H-NMR, GPC and elemental analyses; their thermal behavior was studied by DSC measurements, microscopy under polarized light, and thermogravimetric analyses. The melting points are in the range of 130–280°C. All of them except of those with a high amount of 2,5-dimethyl hydroquinone (8) form a nematic phase above their melting point.     

Chiral macrocyclic salen Mn(III) complexes catalyzed enantioselective epoxidation of non-functionalized alkenes using NaOCl and urea H2O2 as oxidants

Two new chiral Mn(III) macrocyclic salen complexes 1a and 1b were prepared for the enantioselective epoxidation of non-functionalized alkenes. A 5 mol% loading of these catalysts in the presence of pyridine N-oxide as an axial base and sodium hypochlorite or urea hydrogen peroxide adduct as oxidant worked well to give respective epoxides in high yields and ee (up to >95% in selected cases). The catalyst 1b with urea hydrogen peroxide adduct as an oxidant was recovered by precipitation with hexane and was reused up to four times with retention of enantioselectivity.     

Livig carbocationic polymerization

Summary Diblock copolymers of isobytylene (IB) — methyl vinyl ether (MeVE) have been prepared by sequential monomer addition by employing 2-chloro-2, 4, 4-trimethylpentane (TMPCl)/TiCl₄ initiating system in the presence of nBu₄NCl or dimethyl-acetamide (DMA) in CH₂Cl₂/hexanes at –80°C. In line with our earlier observations (1), living carbocationic polymerizations (LCPZn) were obtained in the presence of nBu₄NCl (i.e., the molecular weight of the poly(vinyl methyl ether) segment increased upon TiCl₄ addition), however, extensive chain transfer occurred in the presence of DMA. According to column chromatography analysis, the product prepared in the presence of nBu₄NCl is essentially pure PIB-b-PMeVE diblock (96w%) contaminated with a very small amount (4w%) of PIB. In contrast, the product obtained with DMA contains only 21w% PIB-b-PMeVe together with 72w% PIB and 5w% PMeVe homopolymers. This large difference in blocking efficiencies suggests that the structures of the growing species are different in the presence of the common anion salt,nBu₄NCl, and the electron donor, DMA.For paper LIII in this series see Polym. Bull., vol. 29/1     

Alternating copolymerization of 5-oxazolones with electrophilic monomers via zwitterion intermediates

Summary 5-Oxazolone (1a) and 4-methyl-5-oxazolone (1b) were found to serve as a nucleophilic monomer (M_N) toward electrophilic monomers (M_E) like acrylamide (AM) and 2-hydroxyethyl acrylate (HEA). Copolymerizations between these M_N and M_E monomers took place without added initiator at room temperature and at110 °C to give solid polymers having alternating structures of 3 and 4. The molecular weight of these alternating copolymers is not high. The copolymerization mechanism is explained in terms of zwitterionic intermediates involving a proton-transfer step.     

Transformation of cationic polymerization of tetrahydrofuran into anionic block copolymerization of methyl methacrylate

Summary A new approach has been developed to transform the cationic polymerization of tetrahydrofuran (THF) into anionic block copolymerization of methyl methacrylate (MMA). Several telechelic polytetrahydrofurans with secondary amine end-groups (PTHF-NHR, where R = benzyl, n-butyl or phenyl) have been synthesized. The PTHF-NHR, where R is a phenyl group, can be almost completely metallated by sodium naphthalene to form the polymeric anion which will initiate quantitative polymerization of MMA to form a block copolymer, poly(MMA-b-THF-b-MMA), exhibiting thermoplastic elastomer properties of tensile strength 157kg/cm² and elongation 700%.     

Living carbocationic polymerization of p-halostyrenes

The total synthesis of diblock copolymers comprising poly(p-chlorostyrene) (PpClSt) and polytetrahydrofuran (PTHF) segments have been accomplished. The syntheses involved the living polymerization of p-chlorostyrene (pClSt) by the 2-chloro-2,4,4-trimethylpentane/TiCl₄ initiating system followed by the blocking of tetrahydrofuran (THF) from thesec-benzylic chlorine end-group of PpClSt in the presence of AgPF₆ in THF at room temperature and quenching with methanol: A series of PpCISt-b-PTHF diblocks have been prepared. Themolecular weight of the PTHF segments increased with reactiontime. The blocking efficiency (B_eff) calculated by¹H NMRspectroscopy was nearly 100%.Paper XXXV in the series of Living carbocationic polymerization     

Macrocyclic diamide based poly(vinyl chloride) membranes with a high lithium selectivity

Summary Macrocyclic diamides 2, 3 and 4 of 4,4,5,5-tetramethyl-3,6-dioxaoctanedioic acid were prepared. These compounds incorporated in poly (vinyl chloride) membranes show a remarkable selectivity for lithium ions.     

Crystallization from the bulk of isotactic polystyrene in the extended conformation

Summary The extended conformation with non-staggeredtt conformation of the skeletal bonds, has been crystallized from the bulk by exposure of isotactic polystyrene (iPS) films to solvent vapor at room temperature. Due to the predominant intramolecular interaction between the adjacent phenyls, solvent molecules are required to provide the stability required for crystallization. A unit cell witha = 21 A,b = 16.4 A andc = 30.6 A, with 4 chains and 8–16 solvent molecules has been proposed. It is shown that the extended conformation exists with significant perpetuation in the amorphous zones of semicrystalline films containing the threefold helical structure. It is suggested that the lower melting temperature of the extended form is due to the requirement of the presence of the solvent molecule and not due to intramolecular instability.     

Synthesis and photodegradation of poly[2,5-bis(dimethylsilyl)furan]

Summary Poly[2,5-bis(dimethylsilyl)furan] (V), a copolymer with alternating furan and disilyl units, has been prepared by the Wurtz coupling of 2,5-bis(dimethylchlorosilyl)furan (II) with sodium metal dispersion in toluene. Lower molecular weight poly[2,5-bis(dimethylsilyl)furan] (IV) has been prepared by a similar condensation reaction with 2,5-bis(dimethylfluorosilyl)furan (III). IV and V have been characterized by ¹H, ¹³C and ²⁹Si NMR, IR, and UV spectroscopy as well as by GPC, TGA and elemental analysis. Photolysis of V in a benzene/methanol solution results in degradation of the polymer.