Copolymerization and copolymers of N-(2,4,6-tribromophenyl)maleimide with methyl acrylate and methyl methacrylate

N-(2,4,6-Tribromophenyi)maleimide (TBPMI) was copolymerized with methyl acrylate (MA) or methyl methacrylate (MMA) in toluene solution using 2,2′-azoisobutyronitrile as free-radical initiation. The copolymerization reactivity ratios were found to be for the system TBPMI/MA r₁ = 0,095 ± 0,045 (TBPMI) and r₂ = 2,17 ± 0,142 (MA) and for the system TBPMI/MMA r₁ = 0,037 ± 0,042 (TBPMI) and r₂ = 4,32 ± 0,230 (MMA); Q and e values were also calculated. The initial rate of copolymerization, R_p, for TBPMI/MA sharply decreases as the content of TBPMI in the monomer mixture increases but the composition of the feed does not have a strong influence on R_p for the TBPMI/MMA copolymerization system. The course of copolymerization to high conversion is characterized by an increase of conversion up to a mole fraction of TBPMI of 0,7 in the monomer mixture, when MA was used as the comonomer. An opposite behaviour was found with MMA. Its copolymers show a considerable increase of thermal stability as well as of the glass transition temperatures with increasing TBPMI content.     

Poly(methyl methacrylate) containing pyrrole moieties in the side chains

Two synthetic routes to copolymers 7 of methyl methacrylate (MMA) with 2-(N-pyrrolyl)ethyl methacrylate (PEMA, 11 ) are compared. Copolymerization of MMA (4) with 2-bromoethyl methacrylate (BEMA, 3 ) leads to a precursor copolymer 5 . The reactivity ratios are close to unity (r_MMA = 0,90, r_BEMA = 0,92). The polymer-analogous reaction of 5 with N-pyrrolylpotassium (6) runs to 99% conversion of the BEMA units. The synthesis of PEMA (11) is presented. The reactivity ratios of copolymerization of this monomer (11) with MMA (4) are determined to r_MMA = 1.05 and r_PEMA = 1,65. Copolymers 7 are further characterized by ¹H nuclear magnetic resonance, infrared spectroscopy, gel-permeation chromatography and differential scanning calorimetry.     

Polymerizations of 1-(9-anthryl)ethyl methacrylate and charge-transfer complex formations with its polymers

1-(9-Anthryl)ethyl methacrylate (9AEMA) was prepared by condensation of 1-(9-anthryl)ethanol with methacryloyl chloride. The rate of AIBN initiated polymerization of 9AEMA in benzene at 60°C was intermediate between the polymerization rates of styrene and methyl methacrylate. 9AEMA/styrene copolymerization studies at 60°C resulted in the copolymerization parameters r_9AEMA = 0,42±0,07 and r_st = 0,37 ± 0,08. Charge transfer complexes are formed between p- chloranil and the 9AEMA homo- and copolymers. The absorption maxima of the CT-complexes shifted to higher wavelengths with increasing 9AEMA content of the copolymers, whereas the equilibrium constant of the CT-complex formation was independent of copolymer composition. Both the complex formation enthalpies and entropies decreased with increasing 9AEMA content of the copolymers.     

Copolymerization of 2-chloro-N,N-dimethylacrylamide

2-Chloro-N,N-dimethylacrylamide (CNA) does not homopolymerize easily (2% after 12 days) in contrast to 2-chloroacrylic esters. Its copolymerization with styrene (St) and methyl methacrylate (MMA) is governed by the following copolymerization parameters: r_CNA = 0,03 and r_MMA = 3,4; r_CNA = 0,2 ± 0,05 and r_St = 1,5 ± 0,2. The very low rates of copolymerization and the low molecular weights of the copolymers are interpreted on the basis of the formation of sterically hindered resonance stabilized radicals, and of high chain transfer constants.     

Copolymers from tert‐Butyl Methacrylate with Trimethylsilyl Methacrylate or Methacrylic Acid: Models for Resist Polymers

Free radical copolymerisation of tert‐butyl methacrylate ( 1 ) with trimethylsilyl methacrylate ( 2 ) and methacrylic acid ( 3 ) has been investigated. Reactivity ratios for methacrylic acid and tert‐butyl methacrylate indicate an azeotropic copolymerisation (r ₁ = 0.476 ± 0.103; r ₃ = 0.300 ± 0.032), whereas the two esters show preferential incorporation of 2 (r ₁ = 0.170 ± 0.050; r ₂ = 1.170 ± 0.124). Thermal cis‐elimination of isobutylene from the tert‐butyl ester and subsequent formation of six‐membered cyclic anhydride moieties has been studied. For poly(methacrylic acid‐co‐tert‐butyl methacrylate) thermogravimetry could be used to determine copolymer composition. Solvolytic desilylation of the trimethylsilyl ester groups has been investigated as an alternative route to poly(methacrylic acid‐co‐tert‐butyl methacrylate). The tert‐butyl ester is not affected under the conditions of desilylation. Sequence distribution of both copolymers has been calculated using the method introduced by Bruns and Motoc.

Copolymer composition diagram for tert‐butyl methacrylate/methacrylic acid.     

Polymere brenzcatechin-derivate, 1. Über die Copolymerisation von 4-Propenylbrenzcatechin-Derivaten mit Vinylmonomeren durch Tributylboran

The copolymerization of 4-propenylpyrocatechol derivatives, eugenol ( 1 ), isosafrole ( 2 ), and safrole ( 3 ), with vinyl monomers such as acrylonitrile (AN), maleic anhydride (MA), and methyl methacrylate (MMA), by tributylborane (TBB) was investigated in cyclohexanone at 30°C in a nitrogen atmosphere. These propenyl compounds copolymerized with AN and MA. However, only homopolymerization occurred when they were reacted with MMA under the same conditions. The following monomer reactivity ratios were determined for the systems AN/propenylpyrocatechin derivative/TBB (M₁ = AN): AN/ 1 /TBB-system: r₁ = 2,2 and r₂ = 0, AN/ 2 /TBB-system: r₁ = 0,28 and r₂=, AN/ 3 /TBB-system: r₁ = 1,8 and r₂ = 0. This result     

Copolymers of N-vinyl-2-pyrrolidone and 2-(dimethylamino)ethyl methacrylate, 1. Synthesis,characterization, quaternization

2-(Dimethylamino)ethyl methacrylate (DMAEM) — N-vinyl-2-pyrrolidone (VP) copolymers were synthesized and characterized. The copolymerization parameters were determined: r_VP = 0,61, r_DMAEM = 11,41. The tacticity of DMAEM sequences and the distribution of monomer units were estimated. Then, the experimental conditions for the quaternization of the copolymers with alkyl bromides were defined. The modified copolymers were characterized and the mechanism of the quaternization reaction was studied via potentiometry.     

Solvent effects on free-radical polymerization, 2. IR and NMR spectroscopic analysis of monomer mixtures of methyl methacrylate and N-vinyl-2-pyrrolidone in bulk and in model solvents

Binary systems of methyl methacrylate (MMA)/N-vinyl-2-pyrrolidone (NVP) and MMA/N-methyl-2-pyrrolidone (NMP) with NMP as saturated model of NVP and of NVP/methyl isobutyrate (MiB) with MiB as saturated model of MMA were investigated by means of IR and NMR spectroscopy. Investigations were carried out at room temperature or at 60°C in CHCl₃ (IR) or CDCl₃ and C₆H₁₂/C₆D₁₂ (NMR). It can be concluded from IR and NMR spectra that the polarity of MMA increases in the presence of NVP and the polarity of NVP decreases in the presence of MMA. Equilibrium constants K of complex formation were determined to: K = 0,169 ± 0,037 L · mol^?1 for MMA/NVP at 30°C, 0,112 ± 0,024 L · mol^?1 for NVP/MiB at 60°C and 0,125 ± 0,030 L · mol^?1 for MMA/NMP at 60°C.     

Molecular design of block and graft copolymers by vinyl-substituted xanthates

The selective polymerization behavior of O-ethyl S-4-vinylbenzyl xanthate (1) was investigated on the basis of polymerization kinetics in the dark and in the presence of UV-light. S-Benzyl O-ethyl xanthate (2) was used as a non-polymerizable model compound of 1 to evaluate chain transfer constants. In the homopolymerization and the copolymerization of 1 initiated with AIBN in the dark, styryl groups selectively take part in the polymerization, and xanthate groups are not responsible for it. The monomer reactivity ratios (r ₁ = 0,51 and r_MMA = 0,41) of 1 with methyl methacrylate (MMA) are very close to those of styrene with MMA. The photolysis of 2 was investigated by ¹H NMR. It was found that photodecomposition of 2 takes place at CH₂? S (a) and S? C( = S) bonds (b) with the ratio: a/b = 1/5. The polymerization of MMA was carried out with 1 upon photoirradiation. Number-average degrees of polymerization of the polymers obtained increase linearly with conversion. Block and graft copolymers were prepared by using these macrophotoinitiators.     

Studies on the Copolymerisation of N‐Arylmaleimides with Alkyl(meth)acrylate

The paper describes the synthesis, characterisation and polymerisation of N‐phenylmaleimide (NPM) and N‐tolylmaleimide (NTM) with butyl acrylate. Eight copolymer samples were obtained by varying the mole fraction of N‐arylmaleimide in the initial feed from 0.2 to 0.7. Structural and molecular characterisation of the samples was done using ¹H NMR spectroscopy and intrinsic viscosity measurement. Copolymer composition was determined by taking the ratio of intensities of signals due to —OCH₂ (butyl acrylate) at δ = 4.0 ± 0.1 ppm and aromatic proton at δ = 7.1–7.4 ppm of NPM/NTM. The reactivity ratio of NPM: butyl acrylate and NTM: butyl acrylate were found to be r₁ = 2.49 ± 0.01 : r₂ = 2.83 ± 0.03 and r₁ = 0.48 ± 0.04 : r₂ = 1.75 ± 0.04, respectively. NTM showed much less reactivity as compared to NPM. Thermal stability of the copolymers was evaluated by recording TG/DTG traces in nitrogen atmosphere. Tercopolymers were also prepared by taking 0.3/0.5 and 0.4/0.4 mole fraction of MMA/NPM or NTM. The mole fraction of butyl acrylate in all these tercopolymers was kept constant at 0.2. Structural, molecular and thermal characterisation was also carried out.     

Free-radical polymerization of methyl methacrylate initiated by N,N-dimethylaniline

N,N-Dimethylaniline (DMA) does initiate the free-radical polymerization of methyl methacrylate (MMA), methyl acrylate, and methyl vinyl ketone. The overall rates of polymerization of MMA were obtained at 40, 50, and 60°C. From the results of a detailed kinetic investigation, the activation enthalpy and activation entropy of polymerization were calculated as 63,2 kJ mol^?1 and ?153 J mol^?1 K^?1 at 60°C. Rate equation was also obtained as R_p = k[DMA]^1/2[MMA]^3/2 and the polymerization was inhibited by benzoquinone. Though styrene alone was not polymerized by DMA, the copolymerization of MMA with styrene by DMA (reactivity ratios: r_MMA=0,45 and r_St=0,50) followed a typical free-radical mechanism. An electron-transfer complex between DMA and MMA is proposed as the initiation species.     

Synthesis,polymerization, and copolymerization of lactams containing vinyl groups

Two new lactam monomers containing vinyl groups were synthesized, namely 1-benzyl-3-methylene-5-methyl-2-pyrrolidone ( 1 ) and 5-oxo-2-pyrrolidinylmethyl methacrylate ( 2 ). Their homopolymerization and copolymerizations with methyl methacrylate (MMA), styrene, or methylacrylate were studied. The copolymerization parameters r₁ and r₂ were also evaluated. Poly( 1 ) is a stable polymer which decomposes at ≈ 300°C under nitrogen and at 250°C in air. Its pyrrolidone ring is resistant towards acids and bases.     

Atom‐Transfer Radical Copolymerization of Furfuryl Methacrylate (FMA) and Methyl Methacrylate (MMA): A Thermally‐Amendable Copolymer

Polymers of furfuryl methacrylate (FMA) are interesting materials because of the presence of the furfuryl group as the reactive diene functionality in the pendent group. Copolymers of FMA and MMA were prepared using atom‐transfer radical polymerization (ATRP) catalyzed by CuCl, in combination with HMTETA as a ligand at 90 °C. It was very difficult to prepare by conventional radical polymerization because of several side reactions involving the reactive diene group. The copolymer composition was calculated using ¹H NMR studies. The reactivity ratios of FMA and MMA (r₁ and r₂) were determined using the Finemann‐Ross and Kelen‐Tudos linearization methods. The reactivity ratios obtained were r₁ = 1.56 and r₂ = 0.56. Diels‐Alder chemistry was carried out using the reactive diene of the copolymers and a maleimide as the dienophile. Interestingly, the resultant material was observed to be thermo‐reversible as evidenced by FT‐IR spectroscopy and DSC studies.

     

Reactivity of N-alkylated cyclic iminoether salts having vinyl groups, 4. Radical polymerization and copolymerization of 3-methyl-2-vinyl-5,6-dihydro-4H-1,3-oxazinium trifluoromethanesulfonate

Radical homopolymerization and copolymerizations of a new ionic monomer, 3-methyl-2-vinyl-5,6-dihydro-4H-1,3-oxazinium trifluoromethanesulfonate ( 2c ), were studied. The homopolymerization was initiated with 2,2′-azoisobutyronitrile or benzoyl peroxide in acetonitrile to produce a polymer, poly[1-(3-methyl-5,6-dihydro-4H-1,3-oxazinium-2-yl)ethylene] ( 3c ), with a relatively low solution viscosity ([η] ≈ 0,2). The monomer was found to be copolymerizable with both electron-rich (styrene and butyl vinyl ether) and electron-deficient monomers [methyl methacrylate (MMA)]. For the copolymerization of the monomer and MMA the reactivity ratios r₁ = 0,31 and r₂ = 0,37 (MMA) were determined. From these values the Q and e values were calculated to be 3,7 and 1,9, respectively. The e-value is one of the highest among vinyl monomers reported thus far, which is consistent with the anionic polymerizability of monomer 2c .     

Formaldehyde polymers, 25. Copolymerization of 6,8-dimethyl-4-oxo-5-chromanylmethyl acrylate with styrene,methyl methacrylate,and vinyl chloride

The free radical copolymerizations of 6,8-dimethyl-4-oxo-5-chromanylmethyl acrylate (DCA) with styrene (St), methyl methacrylate (MMA), and vinyl chloride (VC) by the solution polymerization method were studied. For copolymerization of DCA(M₁) with St(M₂), the reactivity ratios were r₁=0,32, r₂=0,70; with MMA(M₂) they were r₁=0,43, r₂=2,00; and with VC(M₂) they were r₁=4,00, r₂=0,08. The Q and e values for DCA were 0,54 and 0,42, respectively. It was also shown that the chromanone skeleton acts as UV-absorber, and inhibits photodegradation of the copolymers.     

Combining ATRP of Methacrylates and ROP of L,L‐Dilactide and ε‐Caprolactone

Coupling atom transfer radical polymerization (ATRP) and coordination‐insertion ring‐opening polymerization (ROP) provided a controlled two‐step access to polymethacrylate‐graft‐polyaliphatic ester graft copolymers. In the first step, copolymerization of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) was carried out at 80 °C at high MMA concentration by using ethyl 2‐bromoisobutyrate and [NiBr₂(PPh₃)₂] as initiator and catalyst, respectively. Kinetic and molar masses measurements, as well as ¹H NMR spectra analysis of the resulting poly(MMA‐co‐HEMA)s highlighted the controlled character of the radical copolymerization, while the determination of the reactivity ratios attested preferential incorporation of HEMA. The second step consisted of the ROP of ε‐caprolactone or L ,L ‐dilactide, in THF at 80 °C, promoted by tin octoate (Sn(Oct)₂) and coinitiated by poly(MMA‐co‐HEMA)s obtained in the first step. Once again, kinetic, molar mass, and ¹H NMR data demonstrated that the copolymerization was under control and started on the hydroxyl functions available on the poly(MMA‐co‐HEMA) multifunctional macroinitiator.

Comparison of the SEC traces for the poly(MMA‐co‐HEMA) macroinitiator P2 (line only), the polymethacrylate‐g‐PLA copolymer C2 (line marked by ○), and the polymethacrylate‐g‐PLA C3 (line marked by ?).     

Nonlinear optically active polymethacrylates with high glass transition temperatures

A number of novel nonlinear optically (NLO) active polymethacrylates were prepared from the NLO active methacrylates 2a–d with azobenzene side groups and the bulky comonomer 1-adamantyl methacrylate. The polymers exhibit unusually high glass transition temperatures between 160°C and 190°C. The copolymerization parameters of the monomer pair 1-adamantyl methacrylate (1) /Disperse red methacrylate 2b (r₁ = 1,1 ± 0,2, r₂ = 0,8 ± 0,2) show that the two monomers are incorporated almost statistically into the polymer chain. Polymers 3a–d are soluble in common organic solvents and excellent films can be obtained by spin coating. After poling in an electric field of 120 V/μm polymer 3b shows a large electrooptic (EO) coefficient (r₃₃) of 25 pm/V at 633 nm. Within two weeks, only a negligible decay of 7% of the EO coefficient was observed at room temperature. On-line monitoring of the second harmonic generation (SHG) at 100°C showed a fast initial drop (10%) of the SHG signal and subsequently a slow decay of 20% within 10 h. Afterwards, the signal remained almost constant for further 5 h at 100°C. The novel polymers can thus be considered as easy processible NLO materials with a high thermal stability of the chromophore orientation obtained by poling.     

Polymerization of macromonomers, 3. Monomer reactivity ratios in radical copolymerization of poly(tetrahydrofuran) macromonomers with 2-vinylnaphthalene

Methacrylate-terminated poly(tetrahydrofuran) (MA-PTHF) and acrylate-terminated poly-(tetrahydrofuran) (A-PTHF) macromonomers (M₂) were radically copolymerized with 2-vinylnaphthalene (2-VN, M₁). The composition of copolymers was determined by UV spectroscopy taking advantage of the very high absorption coefficient (UV) of the monomeric units of 2-VN in copolymer. The monomer reactivity ratios r₁ and r₂ evaluated are as follows. MA-PTHF: r₁ =1,3 ± 0,21, ± 0,05; A-PTHF: r₁ = 2,5 ± 0,35, r₂ = 0,10 ± 0,05. These reactivity ratios were compared with those in the copolymerizations of 2-VN with the corresponding small monomers and were discussed in terms of polymer (hindering) effect and the concept of equal reactivity of growing chain.     

Polymere Brenzcatechin-Derivate, 3. Darstellung und Eigenschaften von 3,4-Methylendioxybenzyl-methacrylat und seinen polymeren Derivaten

3,4-Methylenedioxybenzyl methacrylate ( 3 ) was synthesized from 3,4-methylenedioxybenzyl alcohol ( 2 ) and methacryloyl chloride. 3 was radically polymerized with tributylborane and copolymerized in cyclohexanone at room temperature under nitrogen. The following monomer reactivity ratios were determined M₁ = 3 : r₁ = 0,68 and r₂ = 0,40 for M₂ = styrene, r₁ = 0,78 and r₂ = 0,16 for M₂ = acrylonitril, and r₁ = 0,28 and r₂ = 1,47 for methyl methacrylate. Polymeric derivatives having 3,4-dihydroxybenzyl units in the side chains were prepared from homo- and copolymers of 3 . The thermal stability and redox behaviour of these polymers were investigated.     

Die thermische polymerisation von methylmethacrylat, 3. Verhalten des ungesättigten dimeren bei der polymerisation

The thermal polymerization of methyl methacrylate is accompanied by the formation of appreciable amounts of an unsaturated dimer (H-1). The behaviour of H-1 during homopolymerization in presence of an initiator at 60, 80 and 100°C and during copolymerization with MMA in presence of an initiator at 60°C are investigated. The rate of (H-1)-homopolymerization is very low. The transfer constant to monomer H-1 is about C_H-1 = 3·10^?3 at 80°C as received from P_n-determinations. The termination is essentially by disproportionation. The copolymerization parameters as resulting from polymerizations with labeled MMA at 60°C are r_MMA = 1,8 and r_H-1 = 0,33, respectively.