Effect of the polarity of reaction medium and electric field on zwitter-ion polymerization of methacrylonitrile

Istraživan je mehanizam polimerizacije metakrilonitrila inicirane trietilfosfinom u dimetilformamidu i tetrahidrofuranu. Elementarnom analizom pokazano je da je fosfor kemijski vezan na polimerne molekule. Analiza NMR spektroskopijom, kao i mjerenja električne vodljivosti potvrđuju da tijekom inicijacije nastane hibridna ionska struktura. Adicijom monomera na karbanion nastaje makrohibridni ion. Reakcija inicijacije je spora i odre|uje brzinu polimerizacije. Spontana monomolekulna terminacija prisutna je u procesu. Tijekom postojanja aktivni centar može biti u obliku ionskog para ili slobodnog iona. Slobodni ion mnogo je reaktivniji u reakciji rasta lanca. U dimetilformamidu ionski parovi praktički ne sudjeluju u reakciji rasta lanca i polimer nastaje rastom slobodnih iona. Monomolekulna konstanta ravnoteže ionski par – slobodni ion ovisi o dužini makrohibridnog iona. Posljedično, i brzina polimerizacije ovisi o dužini rastućeg lanca. Dobiveni su eksperimentalni dokazi za to i određene elementarne konstante za makrohibridnu ionsku polimerizaciju. Moglo se očekivati da na hibridnu ionsku polimerizaciju snažno utjeće polarnost reakcijske sredine. Zbog toga smo istraživali polimerizaciju metakrilonitrila iniciranu trietilfosfinom u tetrahidrofuranu te utjecaj vanjskoga električnog polja na ovaj sustav. U tetrahidrofuranu polimerizacija je vrlo spora i nastaju samo oligomeri. Dodatkom dimetilformamida smjesi tetrahidrofurana i monomera, tj. porastom dielektrične konstante reakcijske smjese, raste brzina polimerizacije i molekulna masa polimera. Vanjsko električno polje snažno povećava brzinu polimerizacije i molekulnu masu polimera u tetrahidrofuranu. Ti rezultati sugeriraju da porast dielektrične konstante reakcijske sredine, kao i primjena vanjskoga električnog polja omogućuju disocijaciju slabo reaktivnih ionskih parova u jako reaktivne slobodne ione.The mechanism of polymerization of methacrylonitrile initiated by triethylphosphine in dimethylformamide and tetrahydrofuran was investigated. The elemental analysis has shown that phosphorus is chemically bound to the polymeric molecules. Analysis by NMR spectroscopy, as well as conductivity measurements, prove that the zwitter-ion structure is formed in the initiation process. Monomer addition to the carbanion leads to macrozwitter-ion. The initiation reaction is slow and it is the rate determining step. Spontaneous monomolecular termination reaction is inherent to the system. During its life-time, the active centres can exist as either ion pairs or free ions. In the propagation step the free ion is by far the more reactive of the two species. In dimethylformamide the ion pairs play virtually no part in the propagation step and the polymer is formed through the propagation of free ions. The ion pairs-free ions intramolecular equilibrium constant depends on the length of the macrozwitter-ion. Consequently, the polymerization rate depends on the length of the growing chains. The paper presents experimental evidence for this and reports elementary constants for the macrozwitter-ion polymerization. It could have been expected that the zwitter-ion polymerization is strongly influenced by the polarity of the reaction medium. Therefore, we investigated the polymerization of methacrylonitrile initiated by triethylphosphine in tetrahydrofuran, as well as the influence of an external electric field on this system. In tetrahydrofuran polymerization is very slow and only oligomers are formed. Addition of dimetylformamide to tetrahydrofuran – monomer mixture, i.e. an increase in the dielectric constant of the reaction medium, increases the rate of polymerization and molecular weight of the polymer. In tetrahydrofuran, the presence of an external electric field was found to lead to a strong increase in both polymerization rate and molecular weight. These results suggest that an increase of dielectric constant of the reaction medium as well as the application of external electric field both enable the dissociation of low reactivity ion pairs into the highly reactive free ions

Gene drives – cheating evolution

Kod organizama sa spolnim razmnožavanjem i s po dvije kopije svakog kromosoma, svaki alel bilo kojeg gena ima 50% šanse da se prenese na potomstvo (jer svaka gameta prima po jedan alel). Gene drives (hrv. gensko upravljanje) su sebični genetički elementi koji zaobilaze Mendelova pravila nasljeđivanja, pa njihovi aleli imaju šansu prijenosa na potomstvo veću od 50%. U zadnjih nekoliko godina, prirodno prisutni gene drive sustavi u različitim organizmima poslužili su kao inspiracija za dizajniranje sintetskih gene drive sustava u svrhu genetskog modificiranja populacija, a nakon otkrića tehnologije CRISPR-Cas9 ideja je doživjela veliki napredak. Aktualna istraživanja bave se mogućnostima primjene sintetskih gene drive sustava za suzbijanje malarije modifikacijom populacije komarca Anopheles stephensi i supresijom populacije komarca Anopheles gambiae, te za kontrolu populacija glodavaca. Neka od ograničenja uporabe sintetskih gene drive sustava su razvoj rezistencije na gene drive alele, potencijalni nepredvidljivi učinci, nekontrolirano širenje i zlouporaba. Da bi sintetski gene drive sustavi jednog dana mogli funkcionirati u divljim populacijama, istražuju se i mogućnosti supresije razvoja alela rezistentnih na gene drive te načini bolje kontrole širenja gene drive alela radi smanjenja negativnog utjecaja na neciljane vrste.In sexually reproducing organisms, with two copies of every chromosome, each allele of a particular gene has a 50% chance of being passed to progeny - because every gamete receives one of the alleles. Gene drives are selfish genetic elements that surpass the Mendelian laws of inheritance, so that the progeny has a chance greater than 50% to receive the gene drive allele. In the recent years, naturally occurring gene drive systems have inspired biologists to create synthetic gene drive systems that could be used as tools for genetic modification of entire populations. With the help of CRISPR-Cas9 technology, the idea has faced greater improvement. Current research focuses on using synthetic gene drive systems for malaria suppression either by modifying Anopheles stephensi mosquito population or suppressing Anopheles gambiae population, as well as for the population control of rodents. Potential limitations of using synthetic gene drive systems are development of alleles resistant to gene drive, unforseen effects, uncontrolled propagation and malpractice. For the synthetic gene drive systems to work in wild populations in the future, the methods for resistant allele suppression and for lowering the unwanted effects by better confinement to target species need to be further investigated

Apotheosis of the Public Realm: Civic Classicism in New York City\u27s Architecture

In the years around the consolidation of Greater New York in 1898, a renewed interest in republican political theory among progressive liberals coincided with a new kind of civic architecture. For the first time in American history, cities and the urban public emerged as crucial parts of democratic citizenship, at least for progressives such as Frank Goodnow, Frederic Howe, and Herbert Croly. At the same time, New York City was promoted as the nation\u27s cultural and commercial capital: the American metropolis, in Croly\u27s words. Architects, too, played a key role in articulating the city\u27s and the urban public\u27s new status and visibility. New York City was a site for the simultaneous reimagining of citizenship, the public realm, and architectural and urban form. In this context, an informal school of architecture in New York that I call civic classicism developed three distinctive design modalities to reform the city\u27s public space: the ensemble of buildings in a garden-like terrace, the continuous street wall around a historic square, and the free-standing monument juxtaposed to the gridiron urban plan. By attending to issues of publicity--of public space and visibility--broadly considered, architectural works by Carrère & Hastings, Cass Gilbert, and others are shown to be linked to the civic, political concerns of their time. The dissertation thus moves beyond the conventional biases in the historiography of this architecture, which has treated the work in mostly pejorative terms. Chapter one traces the course of the nineteenth-century American architectonic public realm --that is, the ways in which political thought and architectural and urban form conditioned one another-- as a foundation for understanding the changes around 1898. In Chapter two, Herbert Croly\u27s political theory and architectural criticism are studied together to reveal the connections between his republican politics and his pragmatic architectural aesthetics, which championed civic classicism\u27s suitability to the modern city. Chapters three, four, and five examine the three architectural modalities at the Staten Island Civic Center, Bowling Green, and the New York Public Library, respectively. The conclusion briefly suggests some reasons why civic classicism declined in the 1920s and after

Relaksacijska svojstva i staklasti prijelaz ionizacijskim zračenjem umreženih nezasićenih poliesterskih smola

Variations in the co-monomer, styrene content in the unsaturated polyester (UP) resin affect the thermal stability and the mechanical properties. These are governed by the phase behaviour of the mixture. Dynamic relaxation measurements by dielectric related methods show an increas in the phase separation of cured resin with an increase of styrene concentration. Dielectric permittivity was measured by stepwise changing of frequency during 60Co γ-radiation curing at a constant temperature or by the simultaneous change of frequency and temperature after irradiation. Variations in the appearance of the glass relaxation due to varying degrees of immobilization of long range segmental motion in the uncrosslinked fraction by the introduction of the crosslinked phase by γ-radiation is made obvious by dielectric relaxation measurements of UP resins in the range of the gel fraction from zero up to 100%. A continuous shift of the glass transition of the resin and a change of the dielectric relaxation time distribution was observed as radiation crosslinking reaction proceeded. The shape of the dielectric spectrum bands indicated a heterogeneous nature of the transition which increased with the increasing degree of curing. In-source radiation curing of UP resins was studied by combining dielectric, thermal and charging current analyses. The transition reaction times corresponding to the maximum of the derivative (dε’/dt) curves, where ε’ is the dielectric constant, regarded as the transition times at the corresponding frequency, are shorter for higher frequencies than for the lower ones. It is seen that the average relaxation time is shifted continuously by the reaction, while the temperature is constant and the frequency is changed as a parameter. Meanwhile the distribution of relaxation times is in-homogeneously broadened and the oscillator strength decreases. The α- and β-relaxations of UP resins shift to higher temperatures as the radiation dose (and crosslink density) increases. The relaxations, however, do not appear to be equally affected by the curing, β-relaxation being almost completely superposed by α-relaxation. The simulation of the dielectric spectra of the partially radiation crosslinked UP resins by the Geny-Monnerie model can be used for following the phase separation. The fragility index of the UP resins glass transition slightly changes as the styrene concentration increases indicating more fragility. The nuclear magnetic resonance (NMR) spin-lattice T1 and spin-spin T2 relaxation times can be described also by the terms from the Geny-Monnerie model that describes the polymer chain isotropic motion (4-bonds motion, θ) and by the shift from the ideal lattice (3-bonds motion in the ideal lattice, ρ). The thermally stimulated depolarisation currents of radiation and peroxy cured UP resins have been measured in the low temperature range. The study of the decrease of the current intensity as a function of the absorbed dose reveals important differences between the peaks of the spectrum; the low temperature peaks can be attributed to dipolar volume polarisation, and the high temperature peaks to an ionic space charge polarisation. The shift of the peaks may be indicative of plasticization of the polyester by styrene, and of restriction upon motions of the chain imposed by the crosslinks. The αl-peak is a manifestation of the liquid-liquid (Tll) transition, and here it corresponds to the thermally activated disintegration of phase separated structures, which were well documented in the inherently heterogeneous UP resins. From the Tll/Tg ratio, it may be concluded that the liquid-liquid (Tll) transition corresponds to the characteristic crossover temperature Tc derived in the random walk model. The charging current data above Tll and below Tg are very well described by a simple Arrhenius law with the same (or similar) activation energy Elow suggesting that dynamic scaling continues to apply to the glass, with length ξ independent of temperature. The Tll/Tg ratio, from TSD data, is found to be in the range of 1.06 to 1.21. It could be noticed that as the degree of cure increases the temperature at which maximum occurs shifts to higher values. The extent of cure can be detected as a systematic change in TSD current, as the height of the TSD peaks decrease by curing. TSD current measurements reveal the presence of high internal electrical fi elds due to space charges accumulated at the phase boundaries of glass fi bres in fi lled UP resins. The compliance curves from thermomechanical measurements on partially radiation cured UP resins show transitions at increasing temperature by increasing the radiation dose, i.e. degree of crosslinking.Toplinska postojanost i mehanička svojstva određeni su faznim ponašanjem nezasićenih poliesterskih (UP) smola, što je određeno vrstom i sadržajem komonomera. Dinamička relaksacijska mjerenja dielektričnim metodama upućuju na porast faznog razdvajanja umreženih smola s porastom sadržaja stirena. Dielektrična permitivnost mjerena je promjenom frekvencije u koracima za vrijeme 60Co γ-ozračivanja pri stalnoj temperaturi ili istodobno s promjenom frekvencije i temperature nakon ozračivanja. Dielektrična relaksacijska mjerenja umreženih UP smola u rasponu γ-zračenjem umreženoga, geliranog udjela od 0 do 100 % omogućuju uvid u promjene staklaste relaksacije u neumreženoj fazi zbog porasta stupnja imobilizacije segmentnih gibanja dugog dosega. Porast staklišta i promjene razdiobe dielektričnih relaksacijskih vremena opaženi su pri ozračivanjem iniciranoj reakciji umreživanja smole. Oblik dielektričnog spektra indicira heterogenu narav prijelaza, koja raste s porastom stupnja umreženja. Umreživanje zračenjem UP smola praćeno je dielektričnim, toplinskim i strujnim metodama analize u samom polju zračenja. Prijelazna reakcijska vremena, koja odgovaraju maksimumu krivulja derivacije (dε’/dt) i time prijelaznim vremenima pri odgovarajućim vremenima, kraća su pri višima nego pri nižim frekvencijama. Srednja relaksacijska vremena pomiču se sa stupnjem reakcije, pri postojanoj temperaturi, a frekvencija se mijenja kao parametar. Razdioba relaksacijskih vremena nejednoliko se proširuje i oscilatorna snaga se smanjuje. Relaksacijski α- i β-procesi UP smola pomiču se prema višim temperaturama s porastom doze zračenja i gustoće umreženja. Relaksacijski procesi ipak nisu u jednakoj mjeri određeni umreživanjem, pri čemu je β-relaksacija u potpunosti prekrivena α-relaksacijskim procesom. Simulacija dielektričnih spektara djelomično zračenjem umreženih UP smola s pomoću Geny-Monnerieova modela omogućuje praćenje faznog razdvajanja. Indeks lomnosti staklastog prijelaza UP smola raste s porastom sadržaja stirena. NMR (nuklearna magnetna rezonancija) spin-rešetka i spin-spin T2 relaksacijska su vremena opisana također članovima Geny-Monnerieova modela kojima se opisuju izotropna gibanja polimernog lanca (gibanja 4-veze, θ) i pomaci od idealne rešetke (gibanje 3-veze u idealnoj rešetci, ρ). Toplinski potaknute depolarizacijske (TSD) struje zračenjem i peroksidno iniciranih umreženih UP smola mjerene su u niskome temperaturnom području. Pad strujnog intenziteta kao funkcije apsorbirane doze zračenja upućuje na znatne razlike između maksimuma (TSD) spektra; niskotemperaturni maksimumi mogu se pripisati dipolnoj obujamnoj polarizaciji, a visokotemperaturni maksimumi ionskoj polarizaciji obujamnog naboja. Pomak maksimuma može indicirati omekšavanje poliestera stirenom te ograničavanje gibanja polimernih lanaca zbog umreženih točaka. Maksimum αl odražava prijelaz kapljevina-kapljevina(Tll) te odgovara toplinski aktiviranom raspadu fazno razdvojenih struktura koje su dobro dokumentirane u inherentno heterogenim UP smolama. Prijelaz kapljevina-kapljevina(Tll), prema omjeru Tll/Tg, odgovara karakterističnoj temperaturi prijelaza Tc izvedenoj u okviru modela slučajnih koraka. Struja nabijanja iznad Tll i ispod Tg može se vrlo dobro opisati jednostavnom Arrheniusovom jednadžbom s jednakom (ili sličnom) aktivacijskom energijom Elow, što upućuje na proširenje dinamičkog skaliranja na staklasto stanje, s duljinom ξ koja ne ovisi o temperaturi. Omjer Tll/Tg, prema TSD podatcima, određen je u području od 1,06 do 1,21. Umreživanje pomiče temperature maksimuma prema višim vrijednostima. Doseg umreživanja može se pratiti mjerenjima TSD struje budući da visina TSD maksimuma opada s umreženjem. Mjerenje TSD struje staklenim vlakanima punjenih UP smola upućuje na visoka unutarnja električna polja zbog obujamnog naboja nakupljenog na faznim granicama. Krivulje popustljivosti, pri termomehaničkim mjerenjima, djelomično umreženih UP smola pokazuju prijelaze pri rastućim temperaturama s porastom apsorbirane doze zračenja, tj. stupnja umreženja

Preparation of β-Aminoisobutyric Acid from Glycine via the Wolff Rearrangement of Diazoethylketones

A description is given of the conversion of 3-diazo-1-phthalimidobutan-2-one (la) into B-phthalimidoisobutyranilide (Ila) via the Wolff rearrangement7, in aniline solution , and further rearrangement to B -aminoisobutyric acid. The same rearrangement in (-)-a-phenylethylamine solution is also described

SUSTAVI OBRADE TLA U FUNKCIJI EKOLOŠKE STABILNOSTI

Stationary field experiment pertaining to the winter wheat in Croatia was performed during the three seasons. This study’s intention was to examine and diagnose the effect of tillage systems (TS) on soil chemical properties (soil acidity, phosphorus [P], potassium [K], and organic matter content). The TSs were as follows: CT — ploughing up to 30 cm depth, DT — disking up to 8-12 cm depth, LT — loosening up to 35 cm depth, and NT — no-tillage. The experimental design was a randomised block design in four repetitions, in which the basic TS plot amounted to 540 m2. Soil sampling for 0-30 cm soil layer was performed prior to setting up the experiment and subsequent to the three seasons with a total of 320 soil samples. Chemical analysis was performed according to standard pedological procedures. Economic indicators were calculated using economic equations and standards, whereas statistical analysis was performed with SAS 9.3 and Microsoft Excel 2016. Generated results indicate that the expressed accumulation of phosphorus and potassium appeared with a distinct vertical stratification in the systems with shallower tillage or no-tillage. At the same time, these TSs ensured the soil organic matter and soil fertility preservation. A conservable agricultural production of reduced soil tillage systems has its efficiency and vigor while providing soil degradation.Stacionarni poljski pokus za ozimu pšenicu u Hrvatskoj proveden je tijekom triju sezona . Namjera ovoga istraživanja bila je ispitati i dijagnosticirati utjecaj sustava obrade tla (TSs) na kemijska svojstva tla (kiselost tla, sadržaj fosfora, kalija i organske tvari. TSs-i su bili CT — oranje do 30 cm dubine; DT — tanjuranje do 8-12 cm dubine; LT — rahljenje do 35 cm dubine; NT — bez obrade tla. Eksperimentalni dizajn je bio randomizirani blok dizajn u četiri ponavljanja, u kojem je osnovna TSs parcela bila 540 m2 . Uzorkovanje za sloj tla 0-30 cm obavljeno je prije postavljanja pokusa i nakon triju sezona s ukupno 320 uzoraka tla. Kemijska analiza provedena jer prema standardnim pedološkim postupcima. Standardna statistička analiza provedena softverom SAS 9.3 i Microsoft Excel 2016. Dobiveni rezultati upućuju da se na sustavima s plićom obradom ili bez obrade javlja izražena akumulacija fosfora i kalija uz izraženu vertikalnu stratifikaciju. Istodobno ovi TSs-i osiguravaju konzervaciju organske tvari tla i očuvanje plodnosti tla. Poljoprivredna proizvodnja uz primjenu reduciranih sustava obrade tla ima svoju učinkovitost i snagu kroz sprječavanje degradacije tla

Preparation of β-Aminoisobutyric Acid from Glycine via the Wolff Rearrangement of Diazoethylketones

A description is given of the conversion of 3-diazo-1-phthalimidobutan-2-one (la) into B-phthalimidoisobutyranilide (Ila) via the Wolff rearrangement7, in aniline solution , and further rearrangement to B -aminoisobutyric acid. The same rearrangement in (-)-a-phenylethylamine solution is also described

Specifics of controlling calculation in agricultural production

Dinamične gospodarske prilike zahtijevaju od poduzetnika brzu prilagodbu i donošenje brojnih poslovnih odluka, a preduvjet za to je učinkovit sustav menadžmenta i kontrolinga. Cilj rada je opisati značajke i specifičnosti kontrolinga proizvodnje te njegovu ulogu u kontekstu utvrđivanja realne proizvodne cijene i profitabilnosti svakog proizvoda. Iako je primjena kontrolinga u razvijenim tržišnim zemljama uobičajena praksa, hrvatski poduzetnici se teže odlučuju na uvođenja ove metode pri upravljanju i odlučivanju u poslovanju. Kontroling je funkcija i podsustav menadžmenta čija je svrha poboljšanje poslovanja, optimiziranje poslovanja, kapaciteta i resursa te racionalizacija troškova. Uvođenje kontrolinga ima cilj postojeće stanje dovesti do željenog u smislu poslovne učinkovitosti i konkurentnosti, pri čemu svako poduzeće zahtijeva individualan pristup.Dynamic economic conditions require from entrepreneurs to quickly adapt and make numerous decisions, and a prerequisite for this is an effective management and controlling system. Although the application of controlling is a common practice in developed market countries, Croatian entrepreneurs find it difficult to decide to introduce this method when managing and making decisions in business. Controlling is a management function and subsystem whose purpose is to improve operations, optimize operations, capacities and resources, and rationalize costs. The aim of introducing controlling is to bring the existing situation to the desired one in terms of business efficiency and competitiveness, whereby each company requires an individual approach. The aim of the work is to describe the features and specifics of production controlling and its role in the context of determining the real production price and profitability of each product

Calorimetric investigation of high conversion homopolymerization, graft polymerization and copolymerization reactions

Kalorimetrijom je praćen tijek homopolimerizacije, polimerizacije cijepljenjem i kopolimerizacije. Usporedbom s najčešće korištenim metodama pokazane su velike prednosti kalorimetrije: neposredno i kontinuirano mjerenje brzine reakcije neovisno o fizičkom stanju sustava te upotreba samo jednog ispitka u cijelom području konverzija. Točnošću i osjetljivošću mikrokalorimetrija nadmašuje ostale metode. Gel-efekt, koji je drugim metodama teško zamijetiti u spontanoj polimerizaciji stirena, lako je zamijećen kalorimetrijom. Kalorimetrijsko istraživanje kinetike cijepljenja stirena i metil-metakrilata na polietilen prethodno ozračen na zraku pokazalo je da u polietilenu niske gustoće peroksidi imaju glavnu ulogu u reakciji polimerizacije cijepljenjem, dok su u polietilenu visoke gustoće važni peroksidni radikali. Promjena viskoznosti reakcijske sredine tijekom reakcije polimerizacije cijepljenjem, kao i struktura polimera utječu na kinetiku reakcije. Raspad aktivnih čestica s vremenom također se može pratiti kalorimetrijom. Velika prednost kalorimetrije pokazana je u istraživanju kopolimerizacije monomera davatelja i monomera primatelja elektrona. Opaženo je da naizmjenična kopolimerizacija a-metilstirena s maleimidima, bez obzira na omjer komonomera u smjesi, i homopolimerizacija maleimida nisu istodobne, nego homopolimerizacija maleimida počinje samo kada je naizmjenična kopolimerizacija završila, tj. kada je a-metilstiren potrošen. Završetak kopolimerizacije i početak homopolimerizacije precizno je određen kalorimetrijom. Prinos naizmjeničnoga kopolimera bio je blizak teorijski očekivanom prinosu. Kao jak davatelj elektrona, a-metilstiren stvara s primateljima elektrona kao što su maleimidi stabilne komplekse s prijenosom naboja. Natjecateljski karakter reakcija kopolimerizacije i homopolimerizacije posljedica je sudjelovanja kompleksa s prijenosom naboja u reakciji kopolimerizacije.The calorimetry was used to follow the course of polymerization, graft polymerization and copolymerization reactions. Comparison with widely used point-by-point methods has been performed. Great advantages of calorimetry are direct and continuous measurement of the reaction rate independently from the physical state of reaction system and using only one sample for the whole conversion range. The accuracy and sensitivity achieved are better than those achieved by other methods. The gel-effect which is not pronounced in the spontaneous polymerization of styrene and could not be easily detected with other methods has been readily detected by calorimetry. Calorimetric investigation of grafting kinetics of styrene and methylmethacrylate on air-preirradiated polyethylene have shown that in low density polyethylene peroxides have the dominating role in the grafting reaction, while in high density polyethylene peroxy radicals have a significant role. The change of the viscosity of reaction medium in the course of grafting reaction as well as the structure of polymer influence the kinetics of reaction. The decay of active species in time can be followed by calorimetry. The great advantage of calorimetry was demonstrated in investigation of the copolymerization of electron donor and electron acceptor monomers. It was observed that the alternating copolymerization of a-methylstyrene with maleimides, regardless of ratio of comonomers in the feed, and the homopolymerization of maleimides are not simultaneous but are consecutive reactions. Homopolymerization starts only after the completion of alternating copolymerization when a-methylstyrene is exhausted. The end of copolymerization and start of homopolymerization was strictly detected by calorimetry. The conversion of alternating copolymer was close to theoretically expected. a-Methylstyrene as a strong electron donor forms stable charge transfer complexes with electron acceptors like maleimides. The competitive character of copolymerization and homopolymerization is a consequence of the participation of charge transfer complex in the copolymerization reaction