Graphical Abstract Polymers have shown tremendous capacity as biomaterials with degradable polymers holding particular promise. Control over their microstructure and nanostructure as indicated by the blue and orange regions, respectively, allow for the design of complex materials that have desired interactions with host cells and tissues. This review overviews the wide range of degradable polymers that are available to biomedical researchers paying specific attention to new advances that have been made in the past 4 years.
AbstractThe syntheses of N‐2‐phenylallylacrylamide (I) and N‐ethyl‐2‐phenallylacrylamide (II) are described. Both monomers can be polymerized with radical initiators to form cyclopolymers although complete cyclization does not occur. Lewis acids (ZnCl2 in the case of I, Et1.5AlCl1.5 in the case of II) result in the formation of higher molecular weight polymers in a shorter period of time. Polymers of I and II have been hydrolyzed to polyampholytes. The copolymerization of α‐methylstyrene–acrylamide in the presence of azobisisobutyronitrile (AIBN) and ZnCl2 leads to the formation of a 1:1 copolymer, whereas styrene–acrylamide under the same conditions give a copolymer slightly dependent upon the monomer feed composition. Attempted cyclopolymerization of N‐allylacrylamide (monomer I without the phenyl group) with ZnCl2–AlBN was not successful, only crosslinked polymer being obtained. An explanation is offered for the fact that I does not form a perfect cyclopolymer, although the α‐methylstyrene–acrylamide system forms a 1:1 copolymer.
By means of an epoxynovolac resin with BF 3 complex the suitability of measurements of electrical properties for the investigation of curing process and for the evaluation of cured resins is illustrated. The origin of electrical conductivity and polarization is elucidated.
AbstractSubstitution of several mole per cent of the hydroxyl groups of poly(vinyl alcohol) by fluorine results in marked changes in polymer properties. These fluoro poly(vinyl alcohols) (PVAF) form thermally reversible gels in water at low polymer concentrations. In solution, a helical conformation or a random coil containing helical sequences is more in accord with the experimental observations than the random coil structure of poly(vinyl alcohol). This helical hypothesis is supported by high heats of crosslinking of the aqueous thermally reversible gels, the difficult solubility of PVAF in H2O, the insolubility of the PVAF–iodine complex under conditions where the PVA–iodine complex remains soluble, the temperature‐independent high value for the Huggins k ′ slope constant, the greater stability of the PVAF–iodine complex, the shear dependence of the solution viscosity and our inability to form thermally reversible gels by the introduction of fluorine into other water‐soluble polymers which are capable of hydrogen bond formation. Infrared dichroism and deuteration measurements do not differentiate between PVA and PVAF. If this conclusion is correct, PVAF is the first vinyl polymer of which we are aware that maintains a helical conformation in solution.
AbstractThe diad tacticity of poly(isopropyl acrylate) was measured from the β‐proton absorptions of poly(isopropyl acrylate‐α,β‐d2) obtained with a 100 MHz NMR spectrometer, and temperature dependence of the tacticity of the polymers obtained by radical polymerization was determined. Enthalpy and entropy differences between isotactic and syndiotactic addition for poly(isopropyl acrylate) were calculated to give the following values: Δ(ΔS) = 0.7 eu; Δ(ΔH) = 0.51 kcal/mole. In the hydrolysis of poly(isopropyl acrylate‐α,β‐d2), it was found that the rate of hydrolysis of poly(isopropyl acrylate) was dependent on the molecular weight rather than on the tacticity. As for the rate of racemization during hydrolysis, the rate for syndiotactic polymer was much faster than that for the isotactic polymer. The exchange reaction of deuterium at α‐position with hydrogen occurred in all the polymers during hydrolysis reaction.
AbstractDegradation of nylon 66 films of different morphologies was studied in the presence of nitrogen dioxide, ozone, oxygen, and near‐ultraviolet radiation (λ > 2900 Å). Films cast from formic acid solution showed normal random degradation, whereas films cast from benzyl alcohol solutions and dried at elevated temperatures under nitrogen showed very strongly inhibited random degradation. This inhibition may be due to protection of peptide groups by hydrogen bonding with benzaldehyde or benzoic acid or even to their chemical reactions at elevated temperatures. Oxygen was not rigorously excluded during preparation of the films. Degradation of nylon 66 films cast from formic acid solutions at room temperature containing benzaldehyde or benzoic acid, respectively, is also inhibited. The energy of activation for inhibited degradation in presence of nitrogen dioxide is relatively small, indicating that the process is either controlled by diffusion of polymer radicals from medium cages or by diffusion of gases into the polymer. The degradation kinetics can be expressed by “weak”‐link random degradation. The weak links are in the present case unprotected peptide groups. The functional relationship between chain scission rate constants and NO2 pressure is linear.
AbstractThe reaction of carbon disulfide with one or two equivalents of alkali metal (potassium‐ or sodium) was carried out, and the deep red reaction mixture obtained only in diethylene glycol dimethyl ether. The polymerization of vinyl monomers with this reaction mixture was studied. The reaction mixtures of mono‐ and dialkali metal with carbon disulfide induced the polymerization of N‐phenylmaleimide, methyl vinyl ketone, and acrylonitrile but did not induce the polymerization of methyl methacrylate and styrene. In the polymerization of acrylonitrile with this reaction mixture of carbon disulfide with monoalkali metal, the polymerization rate was found to be proportional to the initiator concentration and to the square of the monomer concentration. The activation energy was −1.1 kcal/mole. Similar results were obtained in the case of carbon disulfide with dialkali metal. The polymer yield increased with increasing solvating power of solvents, i.e., diethylene glycol dimethyl ether, dimethyl sulfoxide, hexamethylphosphoramide, dimethylformamide, tetrahydrofuran. In the copolymerization of AN with MMA, the copolymer obtained consisted almost of AN units.
AbstractDielectric constants and losses of four kinds of acrylonitrile–butadiene copolymers of different degrees of polymerization were measured in the glass–rubber transition region. Curves of the dielectric losses against frequency showed asymmetric loss curves as often seen in α‐relaxations of polar polymers. The loci of Cole‐Cole plots of the complex dielectric constants of these copolymers fitted well the loci of Havriliak‐Negami's equation, The distribution parameters (1 − α) and β of the relaxation times were calculated. It is suggested that the mechanism of relaxation of the long chains is governed by a cooperative mechanism consisting of two concurrent motions: the first motion is the segmental relaxation of the polar chains, and the second is the induced motion of the neighboring segments successive to the first one.
AbstractThe kinetics of the radiation‐induced polymerization of ethylene in the presence of various amounts of medium (tert‐butyl alcohol containing 5 vol‐% of water) was studied, and the effect of the amount of medium on the polymerization was investigated. The polymerization was carried out by use of a reactor of 100 ml capacity under the following conditions: temperature, 24 ± 3°C; pressure, 200 kg/cm2; dose rate, 2.0 × 104−1.6 × 105 rad/hr. The amount of polymerized monomer and the rate of polymerization were maximum when about 50 ml of the medium was used. Data obtained with the use of 30, 50, and 90 ml of the medium were analyzed kinetically and the rate constants of each elementary reaction were determined by the method based on a reaction mechanism which contains both first‐ and second‐order terminations for the concentration of propagating radical. These results were compared with those obtained with the use of 70 ml of the medium already reported in the previous paper. The dose rate exponents of the rate of polymerization were about 0.7–0.8. It was found that G values for the initiation of ethylene and the medium were 1.5 and 3.8, respectively, and the rate of propagation was proportional to the fugacity of ethylene. It is supposed that the medium plays an important role in the first‐order termination, because the apparent rate constant of the reaction was larger when a larger amount of medium was used.
AbstractEthyl 2,3‐dicyanoacrylate was prepared from ethyl 2,3‐dicyanopropionate. High molecular weight, 1:1 alternating copolymers of styrene with tricyanoethylene and ethyl 2,3‐dicyanoacrylate were prepared by bulk polymerization with the use of free‐radical initiators. Solution polymerization of styrene with ethyl 2,3‐dicyanoacrylate in acetonitrile gave the highest molecular weight copolymer (ηinh = 0.74). The copolymers showed unusual thermal properties, i.e., an initial break that was 50–75°C lower than that of polystyrene followed by the formation of an intermediate product that was fairly stable to approximately 500°C.
Journal of Polymer Science Part A-1: Polymer ChemistryVolume 10, Issue 8 p. 2463-2467 Note Reaction of acenaphthylene vapor in the presence of polymer films under γ- or ultraviolet irradiation Kiyoshi Hayakawa, Kiyoshi Hayakawa Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this authorKaoru Kawase, Kaoru Kawase Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this authorHiromi Yamakita, Hiromi Yamakita Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this author Kiyoshi Hayakawa, Kiyoshi Hayakawa Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this authorKaoru Kawase, Kaoru Kawase Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this authorHiromi Yamakita, Hiromi Yamakita Government Industrial Research Institute, Nagoya, Hirate-machi, Kita-ku, Nagoya, JapanSearch for more papers by this author First published: August 1972 https://doi.org/10.1002/pol.1972.150100820Citations: 10AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Citing Literature Volume10, Issue8August 1972Pages 2463-2467 RelatedInformation
A technique is described whereby an assessment of the extent of reaction at any time and at any selected depth beneath the surface of a solid film is obtained from infrared spectrophotometric data. The resultant reaction profiles can be used to investigate the kinetics in planes normal to the surface. Group concentration–time curves can be constructed for planes at selected depths parallel to the surface and used to assess the kinetics in such planes. As a result it is possible to study realistically reactions which do not occur homogeneously throughout a solid, e.g., those effected by oxidation, irradiation, plasma treatment, etc.
AbstractHydrogen‐transfer polymerization of acrylamide and Methacrylamide with an optically active amyl alcoholate or n‐amyl alcoholate (sodium, calcium, magnesium, barium, and aluminum) was investigated to 100°C in toluene. The initiation ability of the metal ion of the initiator increased in the order, sodium > barium > calcium > magnesium > aluminum. The optically active polymer was obtained by the polymerization of methacrylamide with an optically active alcoholate (barium or calcium), but was not obtained by the other alcoholates and by the polymerization of acrylamide with the optically active alcoholate. The specific rotation of the optically active polymer obtained was about +1.1° ∼ +1.3°. The hydrolyzed product of the optically active polymer was α‐methyl β‐alanine having optical activity (+1.0°). The initiation mechanisms of the polymerization were thought to be the dehydrogenation of the monomer of the negative ion and the Michael addition reaction with the monomer of the negative ion and the catalyst, and it was confirmed that the optically active polymer was prepared by intermolecular hydrogen transfer mechanism. In the polymerization of MMA with menthol barium and borneol barium as the optically active catalyst, the optically active polymer was obtained.
AbstractThe degradation of two chlorinated polyethylene compounds CPE 25 (45% chlorine) and CPE 16 (36% chlorine) was studied by following their rates of dehydrochlorination at two temperatures, 150°C and 180°C in pure nitrogen and pure oxygen atmospheres. Studies on the powdered polymers showed that the dehydrochlorination rate of CPE 25 is about fourteen times faster than that of CPE 16 in nitrogen atmospheres and only three to four times faster in oxygen. The molded polymers gave a lower rate of dehydrochlorination than when in the powdered form. This effect is attributed to diffusion factors. The antimony oxide brought about an induction period in the dehydrochlorination reaction during which only a small amount of HCl is evolved, followed by a very fast rate of dehydrochlorination both in oxygen and nitrogen atmospheres. The duration of the induction period increases with increase in the Sb2O3 concentration, but is followed by an accelerated HCl loss which is faster when Sb2O3 concentration is higher. This work provides supporting evidence that SbCl3 was formed and lost during degradation. Mechanisms of dehydrochlorination are suggested for the reaction in the case of pure chlorinated polyethylene and for the polymer containing antimony oxide.
Journal of Polymer Science Part A-1: Polymer ChemistryVolume 10, Issue 3 p. 943-946 Note Photopolymerization of acrylonitrile in dimethyl sulfoxide II. Initiation by azobisisobutyronitrile or hydrogen peroxide Hajime Miyama, Hajime Miyama Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this authorNoriho Harumiya, Noriho Harumiya Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this authorAtsushi Takeda, Atsushi Takeda Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this author Hajime Miyama, Hajime Miyama Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this authorNoriho Harumiya, Noriho Harumiya Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this authorAtsushi Takeda, Atsushi Takeda Basic Research Laboratories, Toray Industries, Inc., Kamakura, JapanSearch for more papers by this author First published: March 1972 https://doi.org/10.1002/pol.1972.150100329Citations: 11AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 H. Miyama, N. Harumiya, and A. Takeda, J. Polym. Sci. A-1, in press. 2 M. Yoshida and M. Taniyama, Kobunshi Kagaku, 19, 627, 633 (1962). 3 C. W. Davis and F. A. Ehlers, U.S. Pat. 2,858,290 (1958). 4 P. Smith and A. M. Rosenberg, J. Amer. Chem. Soc., 81, 2037 (1959). 5 H. Kiuchi and M. Watanabe, Kobunshi Kagaku, 21, 37 (1964). 6 D. H. Volman and J. C. Chen, J. Amer. Chem. Soc., 81, 4141 (1959). 7 F. S. Dainton and W. D. Sisley, Trans. Faraday Soc., 59, 1369 (1963). 8 R. D. Burkhart and J. C. Merrill, J. Phys. Chem., 73, 2699 (1969). Citing Literature Volume10, Issue3March 1972Pages 943-946 ReferencesRelatedInformation
AbstractThe preparation of 3‐acrylamido‐3‐methylbutanoic acid by a haloform reaction on diacetone acrylamide and by a Ritter reaction between acrylonitrile and β,β‐dimethylacrylic acid is reported. The properties of this crystalline monomer and its homopolymer are also reported.
AbstractPolypropylene powder, as formed by typical Ziegler catalysts, can conveniently be hydroperoxidized in aqueous slurry. A cationic surfactant and potassium persulfate are used to achieve wetting and initiate oxidation. It is proposed that specific reaction between the quaternary ammonium cations and persulfate anion generates a water‐insoluble persulfate which decomposes to yield a hydrophobic radical species which initiates oxidation. Graft copolymers were prepared by using this polypropylene hydroperoxide, a redox catalyst, and either dimethylaminoethyl methacrylate or n‐butyl acrylate. These graft copolymers, dispersed in polypropylene, form two‐phase systems in the solid state. Under synthesis conditions which are believed to yield long side chains, the dispersed, more polar polymer was found in larger domains than observed with shorter side chains. Polypropylene spherulites were also distorted, although per cent crystallinity of the continuous polypropylene phase was hardly affected by the presence of graft. Mixtures of poly(propylene‐g‐butyl acrylate) and polypropylene are rather extensible and of low modulus. Low temperature tensile impact values are only slightly higher than for pure polypropylene. Addition of poly(butyl acrylate) to these blends increases both the low‐speed modulud and high‐speed tensile impact relative to the two component blends.
AbstractVinyl acetate was polymerized at high initiation rate with 2,2′‐azobis(2,4‐dimethyl valeronitrile) as initiator at 50°C. In this polymerization, the power dependence of polymerization rate on the initiation rate is smaller than at lower concentration of monomer. This dependence was kinetically analyzed at each given concentration of monomer. Average degree of polymerization of polymer formed depends on the concentration of initiator. This dependence was explained by considering chain and primary radical terminations and transfer to monomer of polymer radical, and the initiator efficiency (=0.503) was deduced. It was found that the chain termination is inversely proportional to solvent viscosity, but the primary radical termination is not inversely proportional to solvent viscosity. Further, the value of the primary radical termination rate constant (=1.4 × 109l./mole‐sec) was estimated.
AbstractThe influence of γ‐irradiation on the melting and two solid‐solid transitions, occurring near 19° and 30°C, of polytetrafluorethylene was studied by differential scanning calorimetry. A continuous depression of all three transition temperatures, with increasing dose was observed in a first scan of highly crystalline samples at a heating rate of 20°C/min. Additional information was obtained about the accompanying heats of transition. Values for the number of CF2 units excluded from the crystal lattice per 100 eV energy deposition were calculated by using an equation for the depression of the melting point by chemical impurities. The value obtained of G(–units) = 3.3 ± 0.3 is in agreement with a value of G(chemically damaged units) = 3.0 ± 0.1 previously reported on the basis of scavenging techniques. It is concluded that chemical radiation‐induced damage in this polymer may be estimated by reference to changes in the melting temperature. A value of G(–units) = 1.6 ± 0.2 was obtained by reference to the 19°C transition.
AbstractA series of polyamide‐sulfonamides was synthesized by the interfacial polycondensation of m‐ and p‐chlorosulfonylbenzoyl chlorides with aliphatic and aromatic diamines at room temperature. Most of the polymers obtained were high molecular weight, film‐forming materials. They were all amorphous and were soluble in a wide range of acidic and basic solvents. Both aliphatic and wholly aromatic polyamide‐sulfonamides showed initial breakdown in the range of 320–360°C under thermogravimetric analysis in a nitrogen atmosphere.
