Contribution to the study of the mechanism of curing of unsaturated polyester resins

The mechanism of copolymerization of monomethyl and dimethyl maleates and fumarates with styrene was studied by analysis of the conformation of the acid units of the resulting copolymers. The absorption bands for C?O stretching and OH stretching in the spectra of the copolymers are fully identical. They are quite different from the spectra of the copolymers obtained from maleic anhydride and styrene that are subsequently treated with absolute methanol to give the monoester which is then esterified with diazomethane to give the diester. The acid units of the copolymers derived from maleic anhydride exist in a gauche configuration; copolymers derived from fumaric units exist in a trans conformation. The identity of copolymers derived from maleic units with those derived from fumaric units but not with those derived from maleic anhydride indicates that the first step in the copolymerization of the maleic units is an isomerization to fumaric units, which are actually the genuine comonomers.     

Penultimate effects in the copolymerization of maleic anhydride with electron‐rich styrene derivatives

The (controlled) free‐radical copolymerization of maleic anhydride and styrene or derivatives thereof is often thought to provide nearly perfect alternating copolymers. Here, the RAFT copolymerization of electron‐rich styrene derivatives with maleic anhydride is reported. This copolymerization shows distinct penultimate effects, resulting in polymers with increased incorporation of styrene monomers, that is, where a tendency toward periodic (S‐S‐MA) copolymers exists. This work could be a first step towards periodic copolymers based on maleic anhydride and styrene derivatives. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2932–2939     

A polarity‐activation strategy for the high incorporation of 1‐alkenes into functional copolymers via RAFT copolymerization

A new synthetic methodology for the preparation of copolymers having high incorporation of 1‐alkene together with multifunctionalities has been developed by polarity‐activated reversible addition‐fragmentation chain transfer (RAFT) copolymerization. This approach provides well‐defined alternating poly(1‐decene‐alt‐maleic anhydride), expanding the monomer types for living copolymerizations. Although neither 1‐decene (DE) nor maleic anhydride (MAn) has significant reactivity in RAFT homopolymerization, their copolymers have been synthesized by RAFT copolymerizations. The controlled characteristics of DE‐MAn copolymerizations were verified by increased copolymer molecular weights during the copolymerization process. Ternary copolymers of DE and MAn, with high conversion of DE, could be obtained by using additive amounts (5 mol %) of vinyl acetate or styrene (ST), demonstrating further enhanced monomer reactivities and complex chain structures. When ST was selected as the third monomer, copolymers with block structures were obtained, because of fast consumption of ST in the copolymerization. Moreover, a wide variety of well‐defined multifunctional copolymers were prepared by RAFT copolymerizations of various functional 1‐alkenes with MAn. For each copolymerization, gel permeation chromatography analysis showed that the resulting copolymer had well‐controlled M_n values and fairly low polydispersities (PDI = 1.3–1.4), and ¹H and ¹³C NMR spectroscopies indicated strong alternating tendency during copolymerization with high incorporation of 1‐alkene units, up to 50 mol %. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3488–3498, 2008     

Unsaturated,biobased polyesters and their cross‐linking via radical copolymerization

Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2‐hydroxyethyl methacrylate, N‐vinyl‐2‐pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n‐butoxide. 2D NMR and MALDI‐Tof‐MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by‐product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their T_g values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2885–2895, 2010     

Synthesis and characterization of poly[(3,4-dihydro-2h-pyran)-alt-(maleic anhydride)] and its derivatives: Biologically active polymers

The syntheses of several monomers, bioactive poly[(3, 4-dihydro-2H-pyran)-alt-(maleic anhydride)] and its derivatives, which have different substituents (e.g., acetoxy, methoxy, ethoxy, methoxycarbonyl, formyl, acetoxymethyl, and tosyloxymethyl groups) in the 2-position of the tetrahydropyran ring of the copolymer backbone, are described. The alternating sequences in copolymers of the dihydropyran derivatives and maleic anhydride were obtained from the equimolar and larger ratios of maleic anhydride to dihydropyran derivative at the onset of the copolymerization. The molecular weights of the copolymers were found to be low (M_n = 1000–7500) due to a transfer reaction of the dihydropyran derivatives. Hydrolyses of the anhydride groups in the copolymers without catalyst afforded poly[(dihydropyran)-alt-(maleic acid)] and its derivatives, whereas an additional three copolymers having substituents, e.g., hydroxy, hydroxymethyl, and carboxyl groups were obtained by hydrolyses of the pendent groups (acetoxy, acetoxymethyl, and methoxycarbonyl) with the aid of a hydroxide catalyst. Carbamoyl groups on the polymers were obtained from ammonolysis of methoxycarbonyl groups. The polymers having mercaptomethyl or aminomethyl groups were obtained by substitution of hydrogen sulfide or ammonia for tosyloxylmethyl groups.     

Synthesis of star‐shaped copolymers with methyl methacrylate and n‐butyl methacrylate by metal‐catalyzed living radical polymerization: Block and random copolymer arms and microgel cores

Various star‐shaped copolymers of methyl methacrylate (MMA) and n‐butyl methacrylate (nBMA) were synthesized in one pot with RuCl₂(PPh₃)₃‐catalyzed living radical polymerization and subsequent polymer linking reactions with divinyl compounds. Sequential living radical polymerization of nBMA and MMA in that order and vice versa, followed by linking reactions of the living block copolymers with appropriate divinyl compounds, afforded star block copolymers consisting of AB‐ or BA‐type block copolymer arms with controlled lengths and comonomer compositions in high yields (≥90%). The lengths and compositions of each unit varied with the amount of each monomer feed. Star copolymers with random copolymer arms were prepared by the living radical random copolymerization of MMA and nBMA followed by linking reactions. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 633–641, 2002; DOI 10.1002/pola.10145     

Copolymerization of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride and maleic acid

The free-radical copolymerization of 1,1,3,3-tetraethyl-2,2-diallylguanidinium chloride and maleic acid in bulk and organic solvents forms copolymers with a high tendency of monomer units toward alternation. It is shown that 1,1,3,3-tetraethyl-2,2-diallylguanidinium chloride undergoes copolymerization with maleic acid to give rise to pyrrolidinium structures in the cyclolinear polymer chain.     

Silver recovery with complexing sorbents based on 1-vinyl-1,2,4-triazole

The sorption activity of copolymers based on 1-vinyl-1,2,4-triazole toward silver ions was studied in relation to the copolymer structure and to the kind and concentration of acids. The copolymers were prepared by radical copolymerization of 1-vinyl-1,2,4-triazole with 1,1,3-trihydrotetrafluoropropyl methacrylate and divinylbenzene, with 1,1,3-trihydrotetrafluoropropyl methacrylate, methyl methacrylate, and N,N′-methylenebisacrylamide, with diethylene glycol divinyl ether, and with divinyl sulfide. The copolymers exhibit high sorption activity. They efficiently recover silver cations from acid solutions and behave as anion exchangers.     

Synthesis and helical properties of N‐substituted p‐benzamide random copolymers possessing chiral/achiral and (S)/(R) side chains

Random copolymers of poly(p‐benzamide)s having a methyl‐substituted tri(ethylene glycol) unit as a chiral side chain and a nonsubstituted tri(ethylene glycol) or branching alkyl unit as an achiral side chain were synthesized by copolymerization of N‐substituted 4‐aminobenzoic acid ester monomers with a base in the presence of an initiator. Copolymerizations of the chiral (S)‐monomer with N‐tri(ethylene glycol) achiral monomer and with the racemic monomer were carried out by the addition of a mixture of two monomers and an initiator to a solution of a base all at once, affording the corresponding random copolymers. On the other hand, random copolymerization of the chiral monomer with monomer having an achiral branching alkyl side chain required dropwise addition of the achiral monomer to a mixture of the chiral monomer, the initiator, and the base. These copolymers formed helical structures, but analysis of the CD spectra indicated the absence of cooperativity between the monomer units along the copolymers. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Determination of chain transfer constant to dodecanethiol in styrene/methyl methacrylate and butyl acrylate/methyl methacrylate copolymerization and effect of chain length on composition and stereochemical configuration of copolymers

Free radical copolymerization of styrene/methyl methacrylate (S/MMA) and butyl acrylate/methyl methacrylate (BA/MMA) in the presence of n-dodecanthiol (DDT) has been studied at 60°C in a 3 mol/L benzene solution using 2,2′-azobis(isobutyronitrile) (AIBN) as initiator. Overall chain transfer constant to DDT has been determined for both copolymerization systems, as a function of monomer feed composition using complete molecular weight distribution and the Mayo method. Overall transfer coefficients have values which are dependent on both monomer feed composition and individual comonomer transfer values. Composition, sequence distribution, and stereoregularity of copolymers obtained are, in our experimental conditions, independent of copolymer molecular weight. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2913–2925, 1998     

Spontaneous alternating copolymerization of N-phenylmaleimide with ethyl α-phenylacrylate

The spontaneous copolymerization of N-phenylmaleimide (NPMI) (M₁) with ethyl α-phenylacrylate (EPA)(M₂) were carried out in dioxane at 85°C. A high alternating tendency was observed. The monomer reactivity ratios were r₁ = 0.07 ±0.01 and r₂ = 0.09 ± 0.02. The maximum copolymerization rate and molecular weight occurs at 70–80 mol% (M₁) in feed ratio. The spontaneous alternating copolymerization is considered to be carried out via a contact-type charge transfer complex (CTC) formed between the monomers. Thermogravimetric analyses (TGA) indicate the resulting copolymers have high thermal stability. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2927–2931, 1998     

UV curing of a novel resin derived from poly(ethylene terephthalate)

The synthesis and characterization of photopolymerizable unsaturated polyester resins based on PET waste are described. The resins came from a depolymerization process based on the glycolysis of PET by diethylene glycol (DEG). Different molecular weights of glycolysates were synthesized. Then, the latter was functionalized by a methyl hemiester of maleic acid to obtain unsatured α,ω‐bismaleate PET oligomers. In the presence of an electron donor monomer, such as triethylene glycol divinyl ether, these electron acceptor oligomers were copolymerized by way of charge‐transfer complexes under UV irradiation. The reaction was monitored in situ by real‐time IR spectroscopy to study the kinetics of photopolymerization. This one was studied in relation with the physical and chemical characteristics of oligoesters and the composition of mixtures containing divinyl ethers. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1324–1335, 2007     

Transformation of copolymerization mechanism of N-phenyl maleimide and ethyl phenylacrylate in the mixture of dioxane and pyridine

The copolymerization of N-phenylmaleimide (NPMI) with ethyl phenylacrylate (EPA) in a mixture of dioxane (DIO) and pyridine (Py) was investigated. The apparent monomer reactivity ratio r₁ (NPMI) = 0.07 ± 0.01 and r₂ (EPA) = 0.09 ± 0.02 in DIO was turned to r₁ (NPMI) = 3.67 ± 0.07 and r₂ (EPA) = 0 ± 0.03 in Py. The copolymerization of NPMI and EPA with the fixed feed ratio (mol/mol 1 : 1) in different volume ratio of DIO/Py showed that the copolymer composition might be varied in a wide range from the 93.5% of NPMI contents in copolymer to 48.7%. When the volume fraction of Py in the mixture of DIO and Py was <10%, the copolymer with nice alternating structure was obtained and the copolymerization could be inhibited completely by hydroquinone; if the fraction of Py was >10%, the following two kinds of copolymers were formed: a copolymer in which the content of NPMI increased with the Py and the copolymerization also could be inhibited by hydroquinone and a copolymer with low molecular weight almost completely composed of homopolymer of NPMI and is not affected by radical inhibitor as hydroquinone. The transformation of the copolymerization mechanism from the radical to anionic, which was dependent on the volume ratio of DIO and Py, was suggested. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2755–2761, 1999     

New network copolymers of 1-vinyl-1,2,4-triazole as efficient sorbents of mercury

The possibility of preparing copolymers by radical copolymerization of 1-vinyl-1,2,4-triazole with divinyl sulfide and divinyl diethylene glycol ether in the bulk was examined. The sorption characteristics of the new cross-linked copolymers with respect to mercury(II) ions under static conditions in acid solutions were studied.     

Synthesis and polymerization studies of N-cyanomethanimine monomers

New imine monomers containing C-aryl and N-cyano substituents were synthesized and polymerized by both radical and anionic initiation. Homopolymerization yielded low molecular weight polymers (M_n < 2100). Higher yields were obtained with anionic initiation rather than radical initiation. Radical initiated copolymerization with p-methoxystyrene gave low yields of low molecular weight copolymers. Radical initiated copolymerization with methyl acrylate gave copolymers of 15,000–,32,000 molecular weight in moderate yields, but with rather low incorporation of the imine monomer. The C-substituent affected the anionic and free radical reactivity similarly. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2703–2710, 1997     

RAFT radical copolymerization of beta‐pinene with maleic anhydride and aggregation behaviors of their copolymer in aqueous solution

RAFT copolymerization of beta‐pinene and maleic anhydride was successfully achieved for the first time, using 1‐phenylethyl dithiobenzoate as chain transfer agent in a mixed solvent of tetrehydrofuran and 1.4‐dioxane (1:9, v/v) at a feed molar ratio of beta‐pinene to maleic anhydride as 3:7, and the alternating copolymer was prepared with predetermined molecular weight and narrow molecular weight distribution. Furthermore, using former alternating copolymer as a macro‐RAFT agent, block copolymer poly(beta‐pinene‐alt‐maleic anhydride)‐b‐polystyrene was synthesized in a chain extending with styrene. Hydrolysis of this block copolymer under acidic conditions formed a new amphiphilic block copolymers poly(beta‐pinene‐alt‐maleic acid)‐b‐polystyrene whose self‐assembly behaviors in aqueous solution at different pH were investigated through SEM and DLS. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1422–1429     

Copolymerization of divinyl and monovinyl monomers

The data on the free-radical and cationic copolymerization of divinyl and monovinyl monomers are surveyed. The monomer systems under consideration show promise for the production of crosslinked copolymers free of divinyl monomer blocks. Specific features of the gelation and kinetics of the three-dimensional copolymerization of divinyl monomers are considered. This information is necessary for characterization of crosslinked copolymers useful as matrices for the manufacture of sorbents.     

Copolymerization of unsaturated spiro ortho esters with maleic acid derivatives

The formation of charge-transfer (CT) complexes of unsaturated spiro ortho esters such as 2-methylene-1,4,6-trioxaspiro[4.4]nonane(I) and 2-methylene-1,4,6-trioxaspiro[4.6]undecane(II) with maleic acid derivatives such as maleic anhydride (Manh), dimethyl maleate (DMM), and N-ethyl maleimide (NEM) was ascertained by ultraviolet (UV) and nuclear magnetic resonance (NMR) spectroscopy. The stoichiometries of these complexes were estimated as 1:1. The determination of their equilibrium constants (K) was attempted by using the Hanna-Ashbough equation with NMR spectroscopy. Although K values for I-DMM and II-DMM were specified as 0.266 and 0.336 L/mol, respectively, those for the other systems could not be obtained but were assumed to be negligible small (K ? 1). Copolymerization of these systems which was carried out without an initiator determined that spontaneous copolymerization occurs in all cases but that the copolymerization rates of I-DMM and II-DMM systems are slow. The systems in which Manh or DMM was used as an acceptor monomer gave the alternating copolymers at various monomer to feed ratios. The terpolymerizaton of the I–Manh–DMM system established that DMM takes little part in giving the alternating copolymers I and Manh. Consequently, it was assumed that the reactivity of the CT complex monomer is dependent on the contribution of the dative structure to CT complex.     

Studies in cyclocopolymerization. V. Further evidence for charge-transfer complexes in cyclocopolymerization

Previous work from this laboratory has shown that certain 1,4-dienes which readily undergo cyclocopolymerization with certain alkenes also form charge-transfer complexes with the same alkenes. The results observed and the proposed cyclocopolymerization mechanism are consistent with participation of the charge-transfer complex as a distinct species in the copolymerization. It was the purpose of this investigation to determine whether there was a dilution effect on the relative reactivities of the monomers in support of the charge-transfer participation concept, and whether the results of a suitable terpolymerization study would also support this postulate. In the divinyl ether–fumaronitrile system, the maximum rate of copolymerization occurred at a monomer feed ratio of 1:2 and the composition of the copolymer was also 1:2 at a total monomer concentration of 3 mole/l. However, when the concentration was progressively lowered to 0.5 mole/l. at the same monomer feed ratio, the fumaronitrile content of the copolymer decreased in a linear manner. In a series of terpolymerization experiments with the divinyl ether–maleic anhydride–acrylonitrile system, it was shown that the divinyl ether–maleic anhydride ratio in the terpolymer was always less than 1:1 and had an upper limit of 1:2, regardless of the feed ratio of the termonomers. These results are consistent with the participation of the charge-transfer complex of divinyl ether and maleic anhydride in a copolymerization process with either maleic anhydride or acrylonitrile as the comonomer.     

Polymers from multifunctional isocyanates 14. Alternating copolymers from isocyanato alkenes: Copolymerization of 2-propenyl isocyanate with trimethylsilyl methacrylate as electron acceptor monomer

The copolymerization of 2-propenyl isocyanate ( 1 ) with trimethylsilyl methacrylate ( 2 ) has been investigated. 1 is an electron donor monomer with little tendency to undergo homopolymerization, while 2 is an electron acceptor monomer, capable of free radical homopolymerization. Polymerization to low conversion in benzene gave copolymers with preferential incorporation of 2 and a tendency towards alternating copolymers with increasing amounts of 1 in the feed (1 : 1.13 with a 9 : 1 feed ratio of monomers 1 : 2 ). The glass transition temperatures of the amorphous polymers are in the range from 100–70°C, with a T_g of poly(trimethylsilyl methacrylate) being 135°C. Desilylation occurs in the presence of water, causing an exothermal reaction above the glass transition temperature probably with formation of amides, a reaction that can be used for crosslinking. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 611–616, 1998