bluuebunny/crossref_metadata_2025_split huggingface dataset:
Condensation polymers from 7‐(2′.3′‐dihydroxypropyl)‐theophylline
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru 
Published: April 2003

Abstract7‐(2′.3′‐Dihydroxypropyl)‐theophylline‐3′‐phosphate was synthesized using phosphorus oxychloride in trimethyl phosphate. This compound was condensed using N.N′‐dicyclohexylcarbodiimide as a dehydrating agent in refluxing dimethylformamide to oligomeric products which were separated into four peaks by chromatography using Sephadex G‐25. The major portion of the oligomeric product was found to have a molecular weight of more than 1000 according to gel‐filtration measurement. An oligomeric product was also obtained from the polycondensation of 7‐(2′.3′‐dihydroxypropyl)‐theophylline with phenoxyphosphoryl dichloride.
Polyvinyl alcohol containing N‐derivatives of cytosine, uracil, or adenosine‐5′‐phosphate as pendant groups
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru 
Published: April 2003

AbstractPolyvinyl alcohols (P̄n ca. 500) having a nucleotide or one of its analogs, such as adenosine‐5′‐phosphate, N‐[(2′‐dihydrogenphosphato)ethyl]‐uracil and ‐cytosine, as pendant group were synthesized by condensation using DCC as dehydrating agent in refluxing DMF. The resulting polyvinyl alcohols showed a hypochromic effect up to 4% when mixed with denaturated RNA or DNA in aqueous solution. Low molecular weight PVA (P̄n = 8) containing nucleotide analogs showed no hypochromic effect with DNA or RNA.
Infrared spectra and sequence length distribution in free radical styrene/methacrolein copolymers
Authors: Kálal Jaroslav , Houska Milan , Seyček Otakar , Adámek Petr 
Published: April 2003

AbstractThe method of azoisobutyronitrile (AIBN)‐initiated bulk copolymerization of styrene (S) and methacrolein (M) was employed to determine the monomer reactivity ratios rS = 0.15 and rM = 0.55 (QM = 1.50, eM = 0.78). Quantitative IR spectroscopy in the region of 4000–450 cm−1 was used to elucidate the structure of copolymers. In addition to methacrolein units containing aldehyde groups, the copolymers may also contain cyclic hemiacetal structures formed by the reaction of the carbonyls of the neighboring methacrolein units. The carbonyl absorption at 1722 cm−1 showed that, up to 30 mole‐% methacrolein in the copolymer, almost all methacrolein units have free aldehyde groups. The number of cyclic structures increases with the concentration of methacrolein in the copolymer. The experimental data are in agreement with the statistical theory on the sequence length distribution. The shift of the styrene band at 540 cm−1 to higher wavenumber was investigated and related to the shortening of sequence length of the styrene units. The intensity of the styrene band at 760 cm−1 was related with the distribution of the MSM triads and the copolymer structure.
Methine and α‐methyl proton resonance in methyl acrylate/methacrylonitrile copolymers
Authors: Udipi K. , Harwood H. J. , Friebolin H. , Cantow H.‐J. 
Published: April 2003

AbstractMethyl acrylate (A)/methacrylonitrile (M) copolymers, prepared by emulsion and solution polymerization at 50°C, were characterized by 220 MHz NMR spectroscopy. The methine and α‐methyl proton resonances of such copolymers consisted of three peak patterns, individual resonance areas being assignable to protons centered in various A or M centered triads. Triad fractions determined from methine and α‐methyl resonance patterns were in excellent agreement with calculated values based on reactivity ratios of rA = 0.39 ± 0.06 and rM = 3.56 ± 0.50 for copolymers prepared in emulsion and on reactivity ratios of rA = 0.24 ± 0.02 and rM = 3.21 ± 0.11 for copolymers prepared in solution.
Eine apparatur zur gaschromatographischen verfolgung der metathesereaktion kurzkettiger olefine
Authors: Zowade T. , Höcker H. 
Published: April 2003

AbstractEs wird eine Apparatur beschrieben, die einen Reaktor, kombiniert mit einem Gaschromatographen, umfaßt und die es gestattet, Umsetzungen kurzkettiger Olefine bei der Metathesereaktion schnell und einfach zu erfassen. Die Leistungsfähigkeit der Apparatur wird u. a. am Beispiel der Metathesereaktion von Penten‐2 in Gegenwart des Katalysator‐systems WCl6/C2H5OH/(C2H5)3Al2Cl3 demonstriert.
Oxidative polymerization of 2,6‐xylenol by amine complexes
Authors: Komoto Hiroshi , Ohmura Kaoru 
Published: April 2003

AbstractThe manganese chloride‐tris(2‐hydroxyethyl)amine complex and copper(II)‐pyridine complexes in aqueous solution, which are inactive in organic solvents, have been found to possess a high activity for the oxidative polymerization of 2,6‐xylenol in aqueous solution. The catalytic activity increased remarkably after the addition of alkali to the manganese chloride‐tris(2‐hydroxyethyl)amine complex. Diphenoquinone, the CC coupling product, could not be found, and CO coupling occurred selectively. After adding alkali to the copper(II)‐pyridine complex hydrolysis took place. CO coupling occurs, however, selectively when the copper(II)‐tris(2‐hydroxyethyl)amine complex (1 : 1) is used which is stable against alkali.
Solution properties of poly(methyl methacrylate) in mixtures of two nonsolvents (carbon tetrachloride and n‐alcohols)
Authors: Deb Pramil Chandra , Palit Santi Ranjan 
Published: April 2003

AbstractBinary mixtures of CCl4 and several n‐alcohols comprise cosolvents for poly(methyl methacrylate). The cosolvency has been explained in terms of the thermodynamic approach of SCOTT and also taking into account some specific effects. In the presence of light a reaction between CCl4 and alcohol was observed. Unperturbed molecular dimensions determined in the cosolvents agree well with those reported in the literature.
Zur synthese von oligomeren des nylons‐6.6 nach der anhydridmethode bei höheren temperaturen
Authors: Kusch Peter , Blessing Erika 
Published: April 2003

AbstractIn Modellversuchen wird gezeigt, daß die Synthese von Oligomeren des Nylons‐6.6 nach der Anhydridmethode auch bei Temperaturen weit oberhalb 0°C möglich ist. Hierbei wird festgestellt, daß die gebildeten gemischten Anhydride selbst bei 60°C über einen Zeitraum von einer Stunde stabil sind. Am Beispiel der Synthese eines langkettigen Nylons‐6.6‐Oligomeren werden die Vorteile der Oligomerensynthese nach dem Anhydridverfahren bei 50°C aufgezeigt.
13C Nuclear magnetic resonance spectroscopy of polypropylene, 2. 13C spin‐lattice relaxation study in solution
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô 
Published: April 2003

AbstractProton‐decoupled partially relaxed FOURIER transform (PRFT) NMR of 13C in natural abundance was used to determine spin‐lattice relaxation times (T1) of individual carbons of polypropylene and polyethylene in o‐dichlorobenzene solution and molten polyethylene. It is shown that the relaxation times of polypropylene carbons are independent of the difference in stereochemical configuration. From the values of the nuclear OVERHAUSER enhancement factor it is shown that the excess energy from equilibrium of all 13C in polypropylene and polyethylene are absorbed into lattice mainly through 13C–1H dipolar interactions. It is shown that the effective rotational motion of the skeletal carbons in polypropylene is isotropic. The activation energies of skeletal and internal methyl motions in polypropylene, separately, and skeletal motion in polyethylen in solutions were estimated from the temperature dependence of the correlation time. The assignment of the two peaks appearing in methine carbon region of polypropylene was briefly discussed.
Copolymerization of carbon dioxide and epoxide using dialkylzinc/dihydric phenol system as catalyst
Authors: Kobayashi Makoto , Tang Yang‐Lik , Tsuruta Teiji , Inoue Shohei 
Published: April 2003

AbstractCopolymerization of carbon dioxide with epoxypropane (propylene oxide) in the presence of a diethylzinc/dihydric phenol system was examined. A spectroscopic study of the copolymer revealed that one aromatic group was introduced in the copolymer chain.The osmometric number average molecular weight of the copolymer agrees with the molecular weight deduced from spectroscopic studies. The introduction of the aromatic group into the copolymer chain takes place at the initiation step of the copolymerization, and the catalytic activities of the diethylzinc/phenol systems depend on the presence or the absence of the ZnOXOZn group, where X may be phenylene, naphthylene or other aromatic divalent residues.
Donor acceptor interactions in polymeric systems, 1. Synthesis and properties of polyamides having the carbazole group in the main chain
Authors: Hayashi Yoshio , Tazuke Shigeo 
Published: April 2003

AbstractLow temperature polymerizations of 3,6‐diamino‐9‐ethylcarbazole (1b) with the diacyl dichlorides 2a—e were investigated. In all cases polyamides of high relative molecular mass ([η] ≈ 1·102 cm3 g−1). could be obtained. These polyamides are polymeric electron donors in which the donor units are arranged with regular intervals. Donor acceptor interactions between polyamides and 1,3,5‐trinitrobenzene were studied. In comparison with the monomeric model compound 9‐ethyl‐3,6‐bis(propionylamino) carbazole (1c) the polymer donor showed a higher stability constant. However, there is no regularity in the sequence of stability constants in respect to the number of methylene units separating two carbazole groups. There is a possibility that donor units in the polymer molecules might be located in such a way that each donor unit could cooperate to form a donor‐acceptor complex. No specific interactions between the carbazole groups could, however, be detected by fluorescence spectroscopy. The importance of solvent effects was expressed by the results of absorption and emission spectroscopy.
Vinyl polymerization by metal complexes, 12. Initiation by poly(vinyl alcohol)‐copper(II) chelates
Authors: Kimura Keiichi , Inaki Yoshiaki , Takemoto Kiichi 
Published: April 2003

AbstractThe polymerizations of acrylonitrile, methyl methacrylate and styrene initiated by copper(II) chelates were studied in the presence of carbon tetrachloride. Polymeric and dimeric compounds of vinyl alcohol, that is poly(vinyl alcohol) and 1,3‐propanediol were chosen as ligands. It was found that these systems could initiate the polymerization of methyl methacrylate and styrene effectively. The activity of the polymer chelate was estimated by varying the metal/ligand mole ratio of the initiator system, the pH values and the polymerization temperature. From the results, the mechanism of the free‐radical formation was discussed.
Studies on functional micelles, 1. Preparation of cyclic dipeptides from phenylalanine S‐dodecyl ester
Authors: Kawabata Yasuziro , Kinoshita Masayoshi 
Published: April 2003

AbstractThe hydrochloride of phenylalanine S‐dodecyl ester (2b) reacts in pyridine/water at room temperature to afford 3,6‐dibenzyl‐2,5‐piperazinedione (3) in good yields. Phenylalanine S‐ethyl ester hydrochloride (2a), however, gives only small yields of 3 under the same conditions. This effect is explained with the assumption of a matrix reaction on the micelle surface. In contrast to the S‐ethyl ester the reaction of the S‐dodecyl ester leads to a mixture of two isomeric dioxopiperazines.
Statistical treatment of the grafting reaction
Authors: Ikada Yoshito , Horii Fumitaka 
Published: April 2003

AbstractStatistical calculations were performed for the fundamental quantities in the grafting reaction starting from a substrate polymer with a uniform and a most probable molar mass distribution: e.g., the number of branches in one graft copolymer, the number average degree of polymerization (P̄n) of the backbone of the graft copolymer, the fraction of the mother polymer grafted. It is shown that P̄n of the graft copolymer prepared from a mother polymer with a most probable molar mass distribution decreases at first with increasing number of grafted branches, reaches a minimum and then increases, if the P̄n of the grafted branch is lower than that of the mother polymer. This peculiar behavior is attributed to the fact that the mother polymer molecule with a higher molar mass has a higher probability to participate in the grafting. In addition, the calculation denotes that the synthesized, unfractionated graft copolymer is a polymolecular mixture of the copolymer having branches whose number distribution is remarkably broad.
13C‐NMR spectrum of equibinary (cis‐1,4—1,2) polybutadiene
Authors: Furukawa Junji , Kobayashi Eiichi , Katsuki Nobuyuki , Kawagoe Takahiro 
Published: April 2003

AbstractThe proton decoupled natural abundant 13C‐NMR spectra of equibinary (cis‐1,4—1,2)‐polybutadiene were measured. Assignments of spectra were made for all peaks of the aliphatic range using chemical shift corrective terms estimated for the present system together with GRANT's parameters. Each peak was interpreted in terms of the diad or triad of cis‐1,4 and 1,2 units. The relative intensities of the peaks were in good agreement with the calculated ones from the random assumption with respect to the distribution of cis‐1,4 and 1,2 units. The gas‐chromatographic analysis of the ozonolysis product of the polymers also showed that the sequence distribution of cis‐1,4 and 1,2 units was random.
Feldionen‐ und Elektronenstoß‐Massenspektrometrie von Polymeren und Copolymeren, 3. Copolymere des α‐Methylstyrols mit Methylmethacrylat und Acrylnitril
Authors: Hummel Dieter O. , Düssel Heinz‐Jürgen 
Published: April 2003

AbstractDie Pyro‐Feldionenmassenspektrometrie wurde zur Untersuchung der Primärfragmente und des Abbauverhaltens von α‐Methylstyrol(α‐MS)‐Copolymeren eingesetzt. α‐MS‐Methylmethacrylat(MMA)‐Copolymere depolymerisieren pyrolytisch unter weitgehender Rückbildung der beiden Monomeren. Die Retropolymerisation („Reißverschlußmechanismus„) geht meist über die Verknüpfungsstellen verschiedener Monomerer hinweg. Heterofragmente (α‐MS‐MMA) werden nur mit einer geringen Wahrscheinlichkeit gebildet; noch geringer ist die Konzentration von Homodimeren im Pyrolysat.Primärfragmente des Polyacrylnitrils (PAN) sind Acrylnitril (AN), (AN)2, (AN)3, HCN, C3H5CN, C4H7CN, C5H9CN und höhere Nitrile. Bei der Pyrolyse von α‐MS‐AN‐Copolymeren retropolymerisieren α‐MS‐Sequenzen unter Rückbildung des Monomeren. Die Retropolymerisation macht an Heteroverknüpfungsstellen halt; hierbei bilden sich Heterofragmente des Typs α‐MS‐AN oder α‐MS‐(AN)2. Längere AN‐Sequenzen im Copolymeren führen bei der Pyrolyse wie bei PAN zu AN‐Oligomeren sowie zu höheren Alkencyaniden. Isolierte AN‐Einheiten führen zur Bildung von monomerem AN.
Inelastische Lichtstreuung von Cellulosenitratlösungen
Authors: Meyerhoff Günther , Büldt Georg 
Published: April 2003

AbstractEs wird ein Homodyngerät zur Messung der inelastischen Lichtstreuung beschrieben, das mit einem Argon‐Ionenlaser ausgerüstet ist und mit einem Autokorrelator arbeitet.Das Gerät wird benutzt, um das Verhalten der Fadenmoleküle von Cellulosenitrat in verdünnter Lösung zu untersuchen. Mit dieser Technik wird es möglich, sogar für unabgebaute native Cellulose die Diffusionskoeffizienten der Translation D zu bestimmen, die ein sehr niedriges D (<10−7 cm2 s−1) aufweisen und bisher nur näherungsweise bekannt waren, da die konventionellen Meßtechniken der optischen Beobachtung eines Konzentrationsausgleiches dann recht ungenau werden.
Polymere mit dem Zentralatom eines Makrocyclus in der Hauptkette, 1. Polykondensationsreaktionen mit Phthalocyaninsilicium‐ und Hemiporphyrazingermanium‐Verbindungen
Authors: Meyer Gunter , Wöhrle Dieter 
Published: April 2003

AbstractDihydroxyphthalocyaninsilicium (1b) und Dihydroxyhemiporphyrazingermanium (2b) werden mit verschiedenen einwertigen Alkoholen zu den niedermolekularen Bisalkoxy‐Derivaten (4 bzw. 5) und mit Thiophenol zu den Phenylthio‐Derivaten (11a und 11b) umgesetzt. Mit zweiwertigen Alkoholen und Phenolen köml;nnen Polymere der Struktur 6 und 7 bzw. 8a, b, 9a, b und 10a, b erhalten werden. Dichlorphthalocyaninsilicium (1a) und Dichlorhemiporphyrazingermanium (2a) reagieren mit Phenol bzw. mit Hydrochinon ebenfalls zu niedermolekularen und polymeren Phenoxy‐Derivaten. Die Umsetzung von 1b und 2b mit einund zweibasischen Carbonsäuren führt zu den entsprechenden Estern.Die IR‐Spektren der dargestellten Verbindungen werden diskutiert. Thermogravimetrische und Halbleitermessungen (σ298K ≈ 10−7 bis 10−16Ω−1cm−1) werden beschrieben.
Polymerization by stable carbocations
Authors: Ledwith A. 
Published: April 2003

AbstractSalts of stable carbocations such as triphenylmethyl and tropylium ions were used conveniently to estimate free ion propagation rate coefficients (k) for cationic homopolymerization of a series of alkyl vinyl ethers and N‐vinylcarbazole. Methyl vinyl ether and 2‐chloroethyl vinyl ether gave values of k approximately one order of magnitude less than those of branched alkyl derivatives, and an explanation in terms of conformational effects is presented. Results are compared with those from radiation induced polymerizations, and with data for related hydride ion abstraction processes, in an attempt to evaluate solvent effects on free ion reactivity.The scope and applicability of stable carbocations to cationic polymerizations are surveyed and complicating side reactions exemplified by the systems: xanthylium ion—1,1‐diphenylethylene, tropylium ion—indene, xanthylium ion—THF, C6H5CO+SbCl—THF, and by the effect of perchlorate anions on chain transfer in polymerization of N‐vinylcarbazole.
Solvent effects on radical copolymerization of methyl methacrylate and acrylonitrile
Authors: Zafar M. M. , Mahmud Ruquia , Syed Azhar M. 
Published: April 2003

AbstractRadical copolymerization of methyl methacrylate and acrylonitrile has been studied in six solvents at 60°C, and two monomer feed ratios. The nitrogen contents of the copolymers increases in the order: chloroform < dioxane < benzene < anisole < methyl pentyl ketone < bromobenzene, suggesting an influence of the solvent on the growing radicals.
Relation entre la structure et les propriétés mécaniques dynamiques de polyéthylènes haute pression chlorés
Authors: Humbert Gerard , Quenum Bienvenu M. , Berticat Philippe , Vallet Georges 
Published: April 2003

AbstractLes propriétés mécaniques dynamiques de polyéthylènes chlorés de microstructures bien déterminées sont étudiées en basse fréquence dans un domaine de température compris entre −140°C et + 240°C. Une interprétation du comportement mécanique de ces produits en fonction de la constitution chimique de leurs chaǐnes est proposée.
Evaluation of the degree of branching from intrinsic viscosity measurements. Some properties of poly(vinyl chloride) solutions
Authors: Krozer S. , Carstensen P. , Bodelsen M. , Thirsing A. 
Published: April 2003

AbstractThe degree of branching of commercial samples of poly(vinyl chloride) (PVC) has been investigated. The analysis is based on measurements of the intrinsic viscosity in a Θ‐solvent. The composition of the Θ‐solvent mixture (61,5 Vol.‐% cyclohexanone, 38,5% 1‐butanol) was found from the first cloud point and checked by light scattering. The cluster formation of PVC in cyclohexanone is relatively slow. The analysis of the degree of branching is based on a theory developed earlier. The theory is checked with literature data. The number of branches for some commercial PVC samples are reported.
Low molecular weight polyethylene single crystals: Nucleation
Authors: Alfonso Gian C. , Valenti Barbara , Pedemonte Enrico 
Published: April 2003

AbstractSeveral results are reported concerning the nucleation mechanism connected with the crystallization from a dilute solution containing a sharp fraction of low molecular weight polyethylene. The correlation between the number of nuclei and some parameters of the process, such as the concentration of the solution and the crystallization temperature, suggests a polymolecular mechanism involving the formation of nuclei with various stabilities. Other aspects of the phenomenon are discussed, which probably occur also in the crystallization of the unfractionated polymer.
Strukturuntersuchungen an adsorptionsschichten makromolekularer stoffe, 1. Haftstellenzahlen von linearen polyestern und polystyrol an aerosiloberflächen
Authors: Joppien Günter R. 
Published: April 2003

AbstractDurch direkte IR‐spektroskopische Bestimmungen des Bruchteils gebundener Segmente (Haftstellenzahl) und der adsorbierten Menge von linearen, aliphatischen, gesättigten Polyestern, von Polystyrol und von Butylpropionat, adsorbiert aus verdünnter Lösung an Aerosil, wird die Struktur der Adsorptionsschichten beschrieben. Die Polyester werden mit nahezu allen Kettencarbonylgruppen über Wasserstoffbrücken an maximal 80% der freien Hydroxylgruppen der Aerosiloberfläche gebunden, soweit freie Adsorptionsplätze vorhanden sind. Sie bilden, unabhängig vom Molekulargewicht und von der chemischen Natur der Endgruppen, eine aus kleinen Schlaufen bestehende Schichtstruktur. Im Gegensatz dazu tritt nur jeder dritte aromatische Kern des Polystyrols mit der Aerosiloberfläche in Adsorptionswechselwirkung. Polystyrol und der Modellmonoester vermögen nur 50% der Oberflächenhydroxylgruppen zu besetzen. Die Adsorptionsdaten erfüllen die Langmuirsche Gleichung. Eine gute Übereinstimmung der Ergebnisse besteht zu den Voraussagen einer statistischen Theorie von Silberberg für Polymerenadsorption mit starker Adsorptionswechselwirkung. Die ermittelten Haftstellenzahlen werden den erheblich niedrigeren Werten der Literatur gegenübergestellt und auf der Basis der mittleren Abstände der Oberflächenhydroxylgruppen bei statistischer Verteilung sowie der errechneten maximalen Abstände adsorbierbarer Gruppen in den Polymerketten diskutiert.
Metathetischer abbau von cis,cis‐1,6‐cyclodecadien zu cyclopenten,
Authors: Küpper Friedrich W. , Streck Roland 
Published: April 2003

AbstractNach dem Metathesemechanismus ist die Bildung von Polypentenylenen (3) nicht nur aus Cyclopenten (1), sondern auch aus dem bei der Polymerisation von Cyclopenten im 1. Reaktionsschritt gebildeten 1,6‐Cyclodecadien (2) zu erwarten. Entsprechende Bemühungen, cis,cis‐1,6‐Cyclodecadien (2) in Polypentenylene zu überführen, blieben vor längerer Zeit ohne Erfolg. Die Ursache dafür dürfte in der bei Raumtemperatur vorliegenden Konformation dieses Cycloolefins zu suchen sein. Es gelang nun – in übereinstimmung mit den an Dreidingmodellen gewonnenen Voraussagen – cis,cis‐1,6‐Cyclodecadien‐(2) bei Temperaturen über 50°C in Cyclopenten (1) zu spalten. Dies eröffnet die technisch interessante Möglichkeit, unabhängig von C5‐Crackolefinschnitten reines 1 aus äthylen und Butadien zu synthetisieren.Die massenspektrometrische Analyse der bei den Umsetzungen auftretenden Nebenprodukte gab Hinweise für die Richtigkeit unserer Hypothese über den Verlauf der Polypentenylen‐Bildung und führte zu Erkenntnissen über die Ursachen von häufig unerwünschten Nebenreaktionen bei der Umsetzung von Olefinen mit wolframhaltigen Metathesekatalysatoren.
Synthesis of aromatic polyamides from isocyanatocarboxylic acid chlorides and dimethylsulfoxide or water
Authors: Iwakura Yoshio , Uno Keikichi , Chau Nguyen 
Published: April 2003

AbstractAromatic isocyanatocarboxylic acid chlorides (1a–i) reacted with stoichiometrical quantities of dimethyl sulfoxide in ether to yield poly(N‐carboxyanhydride)s (5) which were converted into polyamides (6) by heating them at elevated temperatures. Isocyanatocarboxylic acid chlorides also reacted with water to produce polyamides 6. The reaction paths were followed by quantitative analysis of carbon dioxide evolved, by measurement of IR spectra, and by thermal analysis of the polymers.
Pharmacologically active polymers, 7. Cyclophosphamide‐ and steroidhormone containing polymers as potential anticancer compounds
Authors: Batz Hans G. , Ringsdorf Helmut , Ritter Helmut 
Published: April 2003

AbstractA number of acrylic and methacrylic esters and N‐vinyl monomers of cyclophosphamide‐ and testosterone derivatives were prepared. The monomers were homopolymerized and copolymerized with hydrophilic monomers to yield watersoluble products.