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.     

Mechanical properties of hydrophilic copolymers of 2-hydroxyethyl methacrylate with ethyl acrylate, n-butyl acrylate, and dodecyl methacrylate

Copolymers were prepared of 2-hydroxyethyl methacrylate, which is strongly hydrophilic, with hydrophobic comonomers having a low glass transition temperature, i.e., ethyl acrylate, n-butyl acrylate, and dodecyl methacrylate. The glass transition temperature, T alpha (1 Hz), of polymers in the dry state (xerogels) was determined by means of dynamic mechanical measurements. The dependence of T alpha on composition in all the three series of copolymers was described in terms of a one-parameter equation. The equilibrium swelling of copolymers in water decreases more steeply than the weight fraction of 2-hydroxyethyl methacrylate. When swollen in water to equilibrium, all copolymers with ethyl acrylate or n-butyl acrylate are in the rubberlike state; their tensile modulus E assumes values in the range 0.17-0.50 MPa. While poly(2-hydroxyethyl methacrylate) has the modulus E = 0.39 MPa, the tensile strength sigma u = 0.32 MPa, and the strain-at-break epsilon u = 1.81, for the weight fraction of the comonomer in the range 0.36 less than or equal to omega 2 less than or equal to 0.56 it is possible to achieve sigma u and epsilon u lying in the respective ranges 0.7-0.9 MPa and 5-7. Copolymers with the dodecyl methacrylate content omega 2 less than 0.2 or omega 2 greater than 0.8 are rubberlike, and at 0.30 less than or equal to omega 2 less than or equal to 0.62 they become leathery; the latter have the modulus E and strength sigma u within the ranges 12-32 and 3-4 MPa, respectively. The stress-strain curves of these copolymers evidence yielding and orientation hardening which have been tentatively explained by the nonhomogeneous composition and structure of the copolymers.     

4-(α,α-dimethylbenzyl)phenyl methacrylate, 3. Synthesis,tacticity and glass transition temperatures of its polymers

Depending on the kind of initiator, anionic polymerization of 4-(α,α-dimethylbenzyl)phenyl methacrylate in toluene at ?78°C led either to highly isotactic or predominantly syndiotactic polymers as determined by ¹³C NMR spectroscopy. The glass transition temperature difference between the syndiotactic and isotactic polymer appeared to be smaller than in case of poly(alkyl methacrylates), probably because of a larger stiffening effect by the bulky aromatic ester group on the isotactic backbone than on the syndiotactic one.     

Glycidyl acrylate plasma glow discharged polymers

A homogeneous glycidyl acrylate polymer (GAP) has been grafted on to polytetrafluoroethylene (PTFE) and polyethylene (PE) using a modified plasma glow discharge technique with glycidyl acrylate. The polymeric layer appears to be extremely stable to acidic media and to common organic solvents. The modified surface can be derivatized via epoxy groups with hydroxy and amino compounds including sugars and amino sugars. These derivatized surfaces have been characterized by Fourier transform infrared (FTIR) spectroscopy and contact angle measurements. The wide variety of compounds which can be attached provides flexibility in the design of surfaces for the study of a range of biological interactions.     

Anionic living polymerization of β-propiolactone initiated with crowned potassium methacrylate: Macromonomers and their copolymers with butyl acrylate

The polymerization of β-propiolactone (βPL) with crowned K⁺ counterion has been shown previously to be a living process. This behaviour was used to prepare macromonomers of poly(βPL) with the methacryloyl reactive group. Poly(βPL) is known to be a crystalline polymer; thus, copolymers of poly(βPL) macromonomers with butyl acrylate gave graft copolymers with properties stemming from this ability. Selected mechanical properties of the copolymers are close to those of acrylic rubbers reinforced with fillers.     

The photolysis of copolymers of methyl methacrylate and methyl acrylate

The photolysis of copolymers of methyl acrylate and methyl methacrylate, covering the entire composition range, is studied with the copolymers in the form of film and in solution, under vacuum and in an atmosphere of oxygen. In film under vacuum, copolymers with high acrylate contents become insoluble, and cross-linking and chain scission may be separated by application of the Charlesby-Pinner equation to sol-gel separation data. Otherwise, the polymer remains soluble, chain scission predominates and may be measured by the changes in number average molecular weight. Differences in the characteristics of chain scission under the four sets of conditions are accounted for in terms of physical factors, such as glass transition temperatures and “cage” recombination of radicals, and chemically in terms of the alternative reactions available to the primary radicals involved.     

Termination kinetics in free-radical bulk terpolymerization — the systems methyl acrylate – butyl acrylate – dodecyl acrylate and methyl methacrylate – butyl methacrylate – dodecyl methacrylate

Termination rate coefficients, k_t , for the terpolymerization of mixtures containing the three acrylates: methyl, butyl, and dodecyl acrylate or the corresponding members of the methacrylate family: methyl, butyl, and dodecyl methacrylate, have been measured via the single pulse (SP)-PLP technique. In the homopolymerization of each of the six monomers an initial plateau region of almost constant k_t is seen which extends at least up to 15% and, for dodecyl acrylate and dodecyl methacrylate, even up to about 50% monomer conversion. Terpolymerization k_t in this region of low and moderate conversion is remarkably well described by a rather simple correlation which exclusively contains homopolymerization k_t and the composition of the monomer mixture. This correlation turns out to be very useful for the modeling of k_t in mixtures of monomers that exhibit such an initial plateau region of k_t . For the systems under investigation, terpolymerization k_t may be estimated within ± 30%. This finding is very remarkable in view of the enormous differences in homopolymerization k_t within each monomer family, e. g., k_t of methyl acrylate exceeds the corresponding dodecyl acrylate value by a factor of 50 (or 5 000%). The entire set of experiments has been carried out at 40°C and 1 000 bar where the signal to noise ratio of the laser-induced single pulse experiments is very satisfactory. No reason is seen why the conclusions about modeling of terpolymerization k_t should not be valid at other reaction conditions including ambient pressure.     

In vitro drug release studies of 2-hydroxyethyl acrylate or 2-hydroxypropyl methacrylate-4-{(1E,4E)-5-[4-(acryloyloxy)phenyl]-3-oxopenta-1,4-dienyl}phenyl acrylate copolymer beads

4-{(1E,4E)-5-[4-(Acryloyloxy)phenyl]-3-oxopenta-1,4-dienyl}phenyl acrylate (APPA) was synthesized by reacting (1E,4E)-1,5-bis(4-hydroxyphenyl)penta-1,4-dien-3-one (HPD) and acryloyl chloride using triethylamine as a base. 2',4-Dichloro-5'-fluoro-1-ene-2-(4-hydroxyphenyl)phenone (EHP) (Arun A, Reddy BSR, Rajkumar M. Polymeric drug for antimicrobial activity studies: Synthesis and characterization. J Bioact Compat Polym 2003;18:219) was used for the controlled release studies. Two types of porous hydrogels were prepared by copolymerizing 2-hydroxyethyl acrylate (HEA) or 2-hydroxypropyl methacrylate (HPMA) with APPA (as a crosslinker) by employing the suspension polymerization technique. The morphology of the hydrogels were characterized by the optical microscopy (OM) and scanning electron microscopy (SEM). Different variations were employed in the preparation of hydrogels to study the effect of crosslinker percentage and drug the loading percentage. Totally 18 types of hydrogels were prepared. The drug-releasing pattern was monitored over a period of 4 weeks using the UV spectroscopic technique by measuring the absorptions at 330.5 nm. In vitro release experiments were carried out at pH 7.4 and pH 9.2. In total, 36 releasing experiments were conducted. The results showed that the controlled release of the drug was dependent on the monomer (HEA or HPMA), crosslinker percentage (CLP), drug-loading percentage (DLP), and pH. The release rate was higher for HEA-based hydrogels when compared with HPMA-based hydrogels in all compositions. The release rate was noticeably higher in pH 9.2 than pH 7.4.     

Liquid-crystalline polymers containing heterocycloalkanediyl groups as mesogens, 6. Liquid-crystalline poly[trans-11-{4-[5-(4-methoxyphenyl)-1,3-dioxan-2-yl]-2,6-dimethylphenoxy}undecyl methacrylate] and poly[trans-11-{4-[5-(4-methoxyphenyl)-1,3-dioxan-2-yl]-2,6-dimethylphenoxy}undecyl acrylate]

The synthesis and characterization of poly[trans-11-{4-[5-(4-methoxyphenyl)-1,3-dioxan-2-yl]-2,6-dimethylphenoxy}undecyl methacrylate] and poly[trans-11-{4-[5-(4-methoxyphenyl)-1,3-dioxan-2-yl]-2,6-dimethylphenoxy}undecyl acrylate] is presented. Both polymers exhibit nematic mesophases and do not present side-chain crystallization. At temperatures higher than 160°C the 1,3-dioxane-2,5-diyl groups undergo a thermally induced trans-cis isomerization. A radical mechanism is proposed for this isomerization.     

Preparation and properties of polymerizable ferroelectric liquid-crystalline acrylate and methacrylate derivatives

(+)-2-Methylbutyl 4-[4-(11-acryloyloxyundecyloxy)benzylideneamino]cinnamate ( 3a ) and (+)-2-methylbutyl 4-[4-(11-methacryloyloxyundecyloxy)benzylideneamino]cinnamate ( 3b ) were synthesized. 3a possesses a chiral smectic C (S^*_c) phase. From electro-optical measurements of 3a , the rise time of the surface director (τ_sr) and the rise time of the bulk director (τ_br) are found to be 0,32 ms and 110 ms, respectively.     

Genotoxicity of acrylic acid, methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate in L5178Y mouse lymphoma cells

A series of monomeric acrylate/methacrylate esters (methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate) as well as acrylic acid were examined for genotoxic activity in L5178Y mouse lymphoma cells without exogenous activation. All five compounds induced concentration-dependent increases in mutant frequency. Small-colony, trifluorothymidine-resistant mutants were primarily induced, which suggests that these compounds may act via a clastogenic mechanism. This prediction was confirmed by the finding that all five compounds produced gross chromosome aberrations in mouse lymphoma cells. The two acrylates were much more potent in their response than acrylic acid. Methyl acrylate (22 micrograms/ml, survival = 18%) induced 385 mutants/10(6) survivors (total mutant frequency less the spontaneous mutant frequency) and 45 chromosome aberrations/100 cells analyzed (total aberrations less the spontaneous background). Ethyl acrylate (37.5 micrograms/ml, survival = 15%) induced 683 mutants/10(6) survivors and 48 aberrations/50 cells analyzed. Acrylic acid (500 micrograms/ml, survival = 22%) induced 245 mutants/10(6) survivors and 37 aberrations/100 cells analyzed. The two methacrylates required higher concentrations to induce a positive response. Methyl methacrylate (2,799 micrograms/ml, survival = 11%) induced 230 mutants/10(6) survivors and 29 aberrations/200 cells analyzed. Ethyl methacrylate was extremely difficult to test because of a plateau in the dose response, over which the toxicity fluctuated from 2% to 37% survival. Positive responses (twice the spontaneous background) were only obtained at toxicity levels with less than approximately 20% survival. A concentration of 1,626 micrograms/ml (survival = 16%) induced 83 mutants/10(6) survivors and 11 aberrations/200 cells analyzed. The evidence suggests that the genotoxicity of these compounds is most likely due to a clastogenic mechanism.     

Light controlled solubility change of polymers: Copolymers of N,N-dimethylacrylamide and 4-phenylazophenyl acrylate

Copolymers of N,N-dimethylacrylamide (DMA) and 4-phenylazophenyl acrylate (PAPA) have been prepared by free-radical copolymerization in dioxane (DMAP-x). The molecular weights of the copolymers show a strong decrease with increasing azobenzene content due to the retardation effect of the azobenzene group. An analogous decrease in molecular weight was found with a number of polymers of DMA which were polymerized in the presence of the non-polymerizable model 4-phenylazophenyl propionate (PAPP). We were able to induce a lower critical solution temperature (LCST) above a certain content of azobenzene moieties in the copolymers (DMAP-x) in contrast to the good water solubility of poly(DMA). Due to the reversible photoisomerization and the concomitant change in the dipole moment of the azobenzene moieties, the LCST depends not only on the content of azobenzene but also on the degree of isomerization. A difference in the LCST up to 20°C was found for dark adapted polymer solutions (0% Z-isomer) and polymer solutions in the photostationary state (ca. 85% Z-isomer). Within this temperature range the polymer can be precipitated by irradiation with light.     

Hydrogen bonding interactions in methacrylate monomers and polymers

It is well appreciated that hydrogen bonding affects a variety of monomer and polymer properties. This study focused on Bis-GMA and urethane dimethacrylate (UDMA) to help elucidate how the strength and nature of specific noncovalent interactions involved with these different functional dimethacrylate structures are expressed in the monomers and polymers. Hydrogen bonding interactions in monomers and comonomer mixtures as well as in appropriate model compounds were examined by FT-IR under ambient conditions, at elevated temperatures and in dilution studies. The investigation of hydrogen bonding extended to monomer viscosity, photopolymerization reaction kinetics, and polymer mechanical properties. The strength of hydrogen bonding was shown not only to be greater for Bis-GMA compared with UDMA, but there is also greater contribution from intermolecular interactions that enhance the hydrogen bonding effects. While UDMA-based polymers reach significantly higher levels of conversion compared with Bis-GMA materials, the stronger hydrogen bonding reinforcement associated with Bis-GMA appears to provide for comparable mechanical strength properties. Depending on the hydrogen bond donor functionality of a monomer as well as its neighboring functional groups, overall monomer structure and comonomers used, hydrogen bonding can favorably affect polymerization reactivity and mechanical properties, even in materials that form highly crosslinked polymeric networks.     

The terpolymerization of methyl methacrylate,methyl acrylate and maleic anhydride

Measurements of the compositions of terpolymers of methyl methacrylate, methyl acrylate and maleic anhydride prepared with benzoyl peroxide initiator from various monomer feeds indicate that the reactivity of methyl methacrylate towards a maleic anhydride ended radical is approximately four times greater than that of methyl acrylate. Although proton magnetic resonance measurements suggest that complexes are formed between methyl methacrylate and maleic anhydride, and methyl acrylate and maleic anhydride, there is no evidence that these complexes affect the kinetics of the polymerization reactions.     

New monomers and photosensitive polymers: the synthesis and polymerization of 2-, 3- and 4-vinylphenyl thiocyanate

The new monomers 2-vinylphenyl thiocyanate ( 6a ), 3-vinylphenyl thiocyanate ( 6b ) and 4-vinylphenyl thiocyanate ( 6c ) were prepared from 2-, 3- and 4-aminoacetophenone ( 1a–c ) as starting materials. The homopolymers ( 7a–c ) and the copolymers 8a–c of the monomers 6a–c with styrene were prepared via free radical polymerization. The polymers, which were obtained as fully soluble and stable materials, were sensitive to UV light. The crosslinking of the polymers 7a–c and 8a–c was investigated under 254 nm UV radiation. From the sensitivity curves of the polymers, gel doses E_g between 2,6 and 95 mJ · cm^?2 were derived.     

Allylic polymers, 1. Synthesis of polyallyl compounds containing 4-oxycarbonylphthalimido units and their polymers

Various polyfunctional allyl compounds containing 4-oxycarbonylphthalimido units were prepared including allyl N-allyl-4-phthalimidecarboxylate ( 3 ), diallyl N-N′-alky-lenebis(4-phthalimidecarboxylates) 8a–c and alkylenebis(N-allyl-4-phthalimidecarboxylates) 9a–e and 11 . These compounds were polymerized by heating them in the presence of dicumyl peroxide or benzoyl peroxide to afford network resins. The thermal stability of these resins was preliminarily investigated using thermogravimetric analysis (TG). The resins from 9e and 11 had essentially no weight loss up to 390 and 360°C, respectively, in nitrogen.