A model of non-Markovian random block copolymers is developed and used to study the effects of blockiness and compositional polydispersity on the phase behaviour of random block copolymers. The model approximates a random copolymer as a series of segments with equal lengths, while each segment is composed of sequences of different monomers drawn randomly from a distribution. The phase behaviour of the model random copolymers is first examined using the random phase approximation (RPA) to study the effects of blockiness and polydispersity on the order-disorder transition. It is observed that the critical point is inversely proportional to the blockiness. Compositional polydispersity is found to facilitate phase separation, and could induce macrophase separation. Next, the model is implemented into self-consistent field theory (SCFT) in order to elucidate the full phase behaviour of symmetric (A/B)-A random copolymers. Finally, the model is applied to the particular case of poly(styrenesulfonate-b-methylbutylene) (PSS-PMB) to study the effects of blockiness on the phase behaviour. In particular, the stability and structure of the `swollen gyroid' morphology predicted by previous Monte Carlo simulations is examined. / Thesis / Master of Science (MSc)

The morphology, crystallization and melting behaviors of a series of ethylene/alpha-olefin copolymers were investigated as a function of comonomer content, comonomer type and processing conditions, including crystallization temperature and time. This was achieved by using a combination of techniques such as Nuclear Magnetic Resonance Spectroscopy (NMR), Differential Scanning Calorimetry (DSC), Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR). The results from the thermal analysis studies clearly indicated the existence of two distinct regions of crystallization, demarcated by a cross-over temperature, 𝑇*. The high temperature region (above 𝑇*) displayed cooling-rate dependence as well as significant hysteresis in crystallinity between cooling and heating processes, similar to that observed in linear polyethylene. This implied that the crystals associated with this region were formed via chain-folded lamellar growth. However, the lower temperature region (below 𝑇*) exhibited reversible changes in crystallinity between cooling and heating, and was found to be independent of the cooling rate. The temporal evolution of secondary crystallization in the copolymers was studied for times ranging from 100-106 min, at different crystallization temperatures (Tx). Two distinct melting endotherms were discerned at crystallization temperatures below 𝑇*. A higher melting endotherm that remained invariant with crystallization time (tx) was associated with lamellar crystals that were formed during primary crystallization. In contrast, both the positions as well as the magnitude of the lower temperature endotherm were found to vary systematically with log (tx). The peak positions of the low endotherm, i.e., the melting temperature of the secondary crystals, were found to consistently extrapolate to the crystallization temperature at very short times. Based on this and other considerations, the secondary crystals were associated with the melting of thin stacks of polymer chains aggregated in the form of "fringed-micelle"-like bundled crystals. The temperature dependence of the kinetic parameters (derived from Avrami and other analyses) above 𝑇* and their invariance below 𝑇*, suggested that the transformation in morphology from lamellar to bundled crystals was gradual and systematic, as the branch content was increased or as the crystallization temperature was lowered. Further verification of this result was obtained via AFM experiments. A systematic variation in morphology from lamellar to spot-like (lamellae were less clearly visible) was clearly discerned on increasing the comonomer content. Furthermore, a second morphological feature represented by bridge-like links between the lamellae, and approximately perpendicular to them, was also observed for some copolymers. This feature was correlated with the bundled crystals discussed above. The presence of an alternate crystal structure, in addition to the usual orthorhombic crystal form expected for linear polyethylene, was also established from the results of the FTIR studies. The relative proportions of the second crystal form in the copolymers as a function of branch content and temperature were modeled and estimated via mathematical deconvolution and curve-fitting processes. Comparing the results to those of the hexagonal rotator phase of n-paraffins, it was proposed that the second crystal structure in the copolymers could be assigned to a hexagonal type unit cell structure. Furthermore, the crystallization and melting behaviors of all three types of copolymers studied - ethylene/1-butene, ethylene/1-pentene and ethylene/1-hexene - were found to be identical to each other, suggesting that the crystallization process examined was independent of branch type for the ethyl, propyl and butyl branches examined. Since the lengthy butyl branch (in the ethylene-hexene copolymers) is not likely to be accommodated in the crystal, it was concluded that all three branch types were predominantly excluded from the crystal structure. Based on the results from these studies, a new model for the crystallization mechanism in these copolymers was proposed and could be further extended to other semicrystalline polymers such as PET, PEEK, PVC, PBT, i-PS and polycarbonate. In this model, the primary and secondary crystallization stages were redefined on the basis of the chain-folded lamellar growth process. According to the model, secondary crystallization involves the generation of the bundled crystals that may be viewed as physical cross-links in the amorphous phase. Therefore, it may provide a means of correlating the temporal evolution of secondary crystallization to the time and temperature dependence of the physical properties of semicrystalline polymers, above their glass transition temperatures. / Ph. D.

No / Crystallization of an isotactic polypropylene (iPP) homopolymer and two propylene/ethylene random copolymers (RACO), induced by high-stress shear, was studied using in situ synchrotron wide-angle X-ray diffraction (WAXD) at 137 °C. The “depth sectioning” method (Fernandez-Ballester Journal of Rheology 2009, 53 (5), 1229−1254) was applied in order to isolate the contributions of different layers in the stress gradient direction and to relate specific structural evolution to the corresponding local stress. This approach gives quantitative results in terms of the specific length of fibrillar nuclei as a function of the applied stress. As expected, crystallization becomes faster with increasing stress—from the inner to the outer layer—for all three materials. Stress-induced crystallization in a RACO with 7.3 mol % ethylene content was triggered at only 1 °C below its nominal melting temperature. The comparison of iPP and RACO’s with 3.4 and 7.3 mol % ethylene monomer reveals the effect of ethylene defects on high-stress shear induced crystallization at 137 °C. It is found that, for a given applied stress, the specific nuclei length formed by flow increases with ethylene content—which is attributed to a greater high molecular weight tail. However, the linear growth rate is significantly reduced by the presence of ethylene comonomers and it is found that this effect dominates the overall crystallization kinetics. Finally, a time lag is found between development of parent lamellae and the emergence of daughter lamellae, consistent with the concept of daughter lamellae nucleated by homoepitaxy on the lateral faces of existing parent lamellae.

The synthesis and preliminary optoelectronic properties of a series of donor-acceptor (DA) type polymers differing by the acceptor units in the polymer backbone were investigated. Polymers CoP1, CoP2 and CoP3 were designed to yield alternating DA segments with randomly distributed different acceptor units along polymer backbone. The combination of neutral state red colored and neutral state green colored materials resulted in different neutral state colors with respect to their additional acceptor unit. 5,8-Dibromo-2,3-bis(4-tert-butylphenyl) quinoxaline, 5,8-dibromo-2,3-di(thiophen-2-yl)quinoxaline and 4,7-dibromobenzo[c][1,2,5]selenadiazole units were perceived as additional acceptor units and these constituents were combined with the 4,7-dibromo-2-dodecyl-2H-benzo[d][1,2,3]triazole unit and the 2,5-bis(tributylstannyl)thiophene moiety via Stille coupling. The resultant donor acceptor type random copolymers indicated that possessing 5,8-dibromo-2,3-di(thiophen-2-yl)quinoxaline as an extra electron deficient with 4,7-dibromo-2-dodecyl-2H-benzo[d][1,2,3]triazole unit on the same polymer backbone originated a neutral state black colored copolymer along with spanning the entire visible spectrum.

No description available.

Στην εργασία αυτή προχωρήσαμε στη μελέτη της αλληλεπίδρασης των ιόντων δισθενούς χαλκού, Cu2+ με στατιστικά συμπολυμερή P(ANa-co-SSNa) του ακρυλικού οξέος, (ANa) με το στυρενοσουλφονικό οξύ (SSNa). Συντέθηκαν τα συμπολυμερή P(ANa50-co-SSNa) και P(AΝa80-co-SSNa) που περιέχουν 50 mol% και 80 mol% ακρυλικού οξέος αντίστοιχα. Τα συμπολυμερή αυτά χαρακτηρίστηκαν με φασματοσκοπία πυρηνικού μαγνητικού συντονισμού 1H NMR. Προχωρήσαμε στην φυσικοχημική μελέτη της αλληλεπίδρασης ιόντων δισθενούς χαλκού, Cu2+, με τα συμπολυμερή P(ANa50-co-SSNa) και P(AΝa80-co-SSNa) χρησιμοποιώντας διάφορες τεχνικές όπως η θολομετρία, η ιξωδομετρία και η φασματοσκοπία UV-vis. Τα πειράματα πραγματοποιήθηκαν σε υδατικά διαλύματα, στα οποία χρησιμοποιήθηκε ως διαλύτης τρισαπιονισμένο νερό, H2O-3D. Για λόγους σύγκρισης μελετήθηκαν επίσης τα αντίστοιχα ομοπολυμερή των μονομερών που αποτελούν τα συμπολυμερή P(ANa-co-SSNa). Έτσι, πραγματοποιήθηκε φυσικοχημική μελέτη της αλληλεπίδρασης των ιόντων Cu2+ με το πολυ(ακρυλικό νάτριο), PANa, και το πολυ(στυρενοσουλφονικό νάτριο), PSSNa, αντίστοιχα. Από την ιξωδομετρική μελέτη προέκυψε πως η εισαγωγή ιόντων χαλκού Cu2+ σε υδατικό διάλυμα πολυμερούς οδηγεί στην μείωση του ανηγμένου ιξώδους. Μάλιστα η μείωση αυτή είναι πιο δραστική καθώς αυξανεται η συγκέντρωση ιόντων Cu2+ στο διάλυμα. Αυτή η συμπεριφορά αποτελεί ένδειξη της συμπλοκοποίησης των ιόντων χαλκού, Cu2+, με τις ομάδες καρβοξυλίων του ακρυλικού οξέος (ΑΑ). Διαπιστώθηκε πως στα συμπολυμερή P(ANa-co-SSNa) τα Cu2+ συμπλοκοποιούνται με τα καρβοξύλια του ακρυλικού οξέος σε αναλογία ιόντων χαλκού προς ομάδες καρβοξυλίων ίση με 1:2. Όσον αφορά στην μελέτη με UV-vis, ενώ στην περίπτωση του ομοπολυμερούς PSSNa δεν υπάρχει κάποια ιδιαίτερη αλληλεπίδραση τύπου συμπλόκου ένταξης μεταξύ του πολυμερούς και των ιόντων του Cu2+, στην περίπτωση του συμπολυμερούς Ρ(ΑNa50-co-SSNa), παρατηρήθηκε μετατόπιση του σήματος των ιόντων Cu2+ (από τα 800 στα 745 nm) παρουσία του συμπολυμερούς. Αυτό είναι χαρακτηριστικό του σχηματισμού συμπλόκου ένταξης μεταξύ των ιόντων του Cu2+ και των ομάδων COO- του συμπολυμερούς. / In the present work we studied the interaction of bivalent copper ions Cu2+ with random copolymers P(ANa-co-SSNa) of acrylic acid (ANa) and styrenesulfonic acid (SSNa). Two copolymers, P(ANa50-co-SSNa) and P(AΝa80-co-SSNa) with 50 mol% and 80 mol% in acrylic acid, respectively, were synthesized and characterized by neutron magnetic resonance spectroscopy, 1H NMR. We proceeded in the physicochemical study of the interaction of bivalent copper ions, Cu2+, with P(ANa50-co-SSNa) and P(AΝa80-co-SSNa) copolymers using techniques like turbidimetry, viscometry and UV-vis spectroscopy. The experiments were performed in aqueous media using 3D water, H2O-3D. For reasons of comparison the respective homopolymers of sodium polyacrylate, PANa, and poly(styrene sulfonate), PSSNa, were also studied. From viscometry it was found that the introduction of copper ions in the polymer aqueous solutions leads to the decrease of the reduced viscosity. Moreover, this decrease is more pronounced as the concentration of Cu2+ increases in the solution. This behavior is indicative of the complexation between Cu2+ with the carboxylate groups of acrylic acid (ΑΑ). In the P(ANa-co-SSNa)/Cu2+ system, it was found that complexation occurs when the ratio of copper ions to carboxylates is equal to 1:2. UV-vis spectroscopy showed that, while in the case of PSSNa homopolymer there is not strong interaction with Cu2+, in the case of the Ρ(ΑNa50-co-SSNa) copolymer, the introduction of the polymer lead to a shift of the maximum absorbance of Cu2+ (from 800 to 745 nm). This was due to the complexation of Cu2+ with the COO- groups of the copolymer.

No description available.

Com o intuito de melhorar a eficiência dos dispositivos emissores de luz poliméricos uma das técnicas utilizadas é o confinamento da conjugação, diminuindo as perdas de energia em sítios de extinção, como fins de cadeia, defeitos ou armadilhas. Além disso, o confinamento quântico permite o controle do comprimento de onda emissivo desses materiais. Um dos mecanismos para o confinamento é a copolimerização, por meio da qual bloco conjugados são inseridos como grupos laterais na cadeia principal ou espaçadores nãoconjugados são inseridos ao longo da cadeia principal conjugada, limitando o comprimento da conjugação. O presente trabalho visou sintetizar e estudar as propriedades de copolímeros estatísticos derivados do PPV contendo segmentos com diferentes graus de conjugação distribuídos aleatoriamente na cadeia e limitados por segmentos não conjugados, e o estudo do comportamento desses materiais como camada ativa em dispositivos emissores de luz (PLEDs). Para a obtenção dos copolímeros randômicos poli[bis-(fenilenovinileno)-stat-(1,8-bis- (2,6-dioximetano-1,4- fenilenovinileno)-dioxioctano)-1,4-fenileno) (RBPV-DODM-PPV) utilizou-se a rota de Wittig, a partir dos monômeros: tereftaldeído (um dialdeído completamente conjugado), 1,8 bis (4 formil 2,6 dimetoxifenoxi) octano (um dialdeído interespaçado por uma cadeia saturada de oitometilenos) e o dicloreto de 1,4 bis (trifenilfosfôniometil) benzeno. Três razões molares x:y dos monômeros dialdeídos foram utilizadas para sintetizar os polímeros randômicos, obtendo-se diferentes proporções e tamanhos de segmentos conjugados distribuídos aleatoriamente nas cadeias poliméricas. Os materiais foram caracterizados por espectroscopia de ressonância magnética nuclear (RMN), no infravermelho, UV-visível, e fluorescência. A técnica de GPC foi utilizada para obtenção das massas moleculares e medidas de Tg foram realizadas por meio de DSC. As propriedades físico-químicas desses materiais foram analisadas em função das razões molares x:y utilizadas nas sínteses. E um estudo estatístico foi realizado para verificar as probabilidades de distribuição dos diferentes segmentos conjugados ao longo da cadeia em função dessas razões. Um estudo da morfologia e espessura dos filmes poliméricos em função dos parâmetros de deposição foi realizado a fim de descobrir as melhores condições para se obter filmes homogêneos e com espessuras da ordem de 20 a 60nm, necessários para alcançar melhores eficiências nos diodos emissores de luz poliméricos (PLEDs). Para a fabricação dos PLEDs foram utilizados ITO e Al como anodo e catodo, respectivamente, e uma camada de 20nm do polímero estatístico como matriz ativa e eletroluminescente. Para facilitar o transporte de portadores de cargas, camadas de PEDOT:PSS e BPBD foram colocadas entre o filme polimérico e os eletrodos. Também foram realizados testes com filmes da molécula Alq-3 como camada transportador-injetora de elétrons. Os dispositivos apresentaram eletroluminescência EL em quase toda a faixa do espectro visível, com máximos na região do ciano, para o copolímero R55 e na região do verde, para o copolímero p37. Baseado no mecanismo de Forster de transferência de energia, concluímos que os filmes desses polímeros estatísticos comportam-se como sistema hospedeiro-hóspede, devido a sobreposição parcial dos espectros de absorção e emissão dos polímeros, ocorrendo a transferência dos excitons-singletos dos segmentos de maior gap para os de menor gap, e, assim, o deslocamento dos centros emissivos para o vermelho e o aumento da eficiência dos dispositivos. / In order to improve the efficiency of polymeric light-emitting devices one of the techniques used is the conjugation confinement, decreasing the losses of energy in quenching sites, such as chain ends, defects or impurities. Moreover, the quantum confinement allows control the emissive wavelength of these materials. One of the confinement mechanisms is the copolymerization, which conjugated blocks are inserted as side groups in the main chain or non-conjugated spacers are inserted along the conjugated main chain, limiting the conjugation length. This study aimed synthesize and study the properties of random copolymers containing segments with different conjugation degrees randomly distributed in the chain and limited by no conjugated segments, and the study of the behaviour of these materials as active layer in a light emitting devices (PLEDs). To obtain random copolymers of poly [bis (fenilenovinileno)-stat-(1,8-bis-(2,6-dioximetano- 1, 4 - fenilenovinileno)-dioxioctano) -1,4-phenylene) (RBPV-DODM - PPV) have been used the Wittig route, from monomers: terephtaldeyde (a dialdeyde completely conjugated), 1.8 - bis (4 - formyl - 2.6 - dimethoxiphenoxi) octane (a dialdeyde interspaced by a saturated chain of eight methylene) and dichloride of 1.4 - a (triphenylphosphoniomethil) benzene. Three molars reasons x: y of dialdeydes monomers were used to synthesize the random polymers, obtaining various proportions and sizes of conjugated segments randomly distributed in the polymer chains. Infrared (IR) and ultravioletvisible (UVvis)spectroscopies, hydrogen nuclear magnetic resonance (1HNMR) spectrometry and differential scanning calorimetry(DSC) were used to characterize the prepared copolymersstructures. Polymers molecular weights were determined by gel permeation chromatography (GPC). The physical-chemical properties of these materials were analyzed by the molars reasons x: y used in the synthesis. And a statistical study was conducted to ascertain the probability of distribution of the various conjugated segments along the chain by these reasons. A study of the morphology and thickness of the polymer films as a function of the parameters of deposition was conducted in order to find out the best conditions to obtain homogeneous films with thickness in the order of 20 to 60 nm, necessary to achieve the best efficiencies in the polymer light emitting diode (PLEDs). For the manufacture of PLEDs ITO and Al were used as anode and cathode respectively, and a layer of 20nm of the statistical polymer as active matrix and electroluminescent. To facilitate the transport of charge carriers, layers of PEDOT: PSS and BPBD were placed between the film and polymer electrodes. Tests were also carried out with films of the molecule Alq-3 as layer electron carrier / injector. The devices had electroluminescence EL in almost the entire range of the visible spectrum, with maximum in the region of cyan, for the copolymer R55 and in the green, for the copolymer p37. Based on the Forster mechanism of energy transfer, we find that the films of these statistical polymers behave themselves as host-guest system, due to partial overlap of absorption and emission spectra of the polymers, occurring the transfer of excitons-singletes of the segments with largest gap for the smaller gap, and thus the displacement of the emission centers for the red.

Com o intuito de melhorar a eficiência dos dispositivos emissores de luz poliméricos uma das técnicas utilizadas é o confinamento da conjugação, diminuindo as perdas de energia em sítios de extinção, como fins de cadeia, defeitos ou armadilhas. Além disso, o confinamento quântico permite o controle do comprimento de onda emissivo desses materiais. Um dos mecanismos para o confinamento é a copolimerização, por meio da qual bloco conjugados são inseridos como grupos laterais na cadeia principal ou espaçadores nãoconjugados são inseridos ao longo da cadeia principal conjugada, limitando o comprimento da conjugação. O presente trabalho visou sintetizar e estudar as propriedades de copolímeros estatísticos derivados do PPV contendo segmentos com diferentes graus de conjugação distribuídos aleatoriamente na cadeia e limitados por segmentos não conjugados, e o estudo do comportamento desses materiais como camada ativa em dispositivos emissores de luz (PLEDs). Para a obtenção dos copolímeros randômicos poli[bis-(fenilenovinileno)-stat-(1,8-bis- (2,6-dioximetano-1,4- fenilenovinileno)-dioxioctano)-1,4-fenileno) (RBPV-DODM-PPV) utilizou-se a rota de Wittig, a partir dos monômeros: tereftaldeído (um dialdeído completamente conjugado), 1,8 bis (4 formil 2,6 dimetoxifenoxi) octano (um dialdeído interespaçado por uma cadeia saturada de oitometilenos) e o dicloreto de 1,4 bis (trifenilfosfôniometil) benzeno. Três razões molares x:y dos monômeros dialdeídos foram utilizadas para sintetizar os polímeros randômicos, obtendo-se diferentes proporções e tamanhos de segmentos conjugados distribuídos aleatoriamente nas cadeias poliméricas. Os materiais foram caracterizados por espectroscopia de ressonância magnética nuclear (RMN), no infravermelho, UV-visível, e fluorescência. A técnica de GPC foi utilizada para obtenção das massas moleculares e medidas de Tg foram realizadas por meio de DSC. As propriedades físico-químicas desses materiais foram analisadas em função das razões molares x:y utilizadas nas sínteses. E um estudo estatístico foi realizado para verificar as probabilidades de distribuição dos diferentes segmentos conjugados ao longo da cadeia em função dessas razões. Um estudo da morfologia e espessura dos filmes poliméricos em função dos parâmetros de deposição foi realizado a fim de descobrir as melhores condições para se obter filmes homogêneos e com espessuras da ordem de 20 a 60nm, necessários para alcançar melhores eficiências nos diodos emissores de luz poliméricos (PLEDs). Para a fabricação dos PLEDs foram utilizados ITO e Al como anodo e catodo, respectivamente, e uma camada de 20nm do polímero estatístico como matriz ativa e eletroluminescente. Para facilitar o transporte de portadores de cargas, camadas de PEDOT:PSS e BPBD foram colocadas entre o filme polimérico e os eletrodos. Também foram realizados testes com filmes da molécula Alq-3 como camada transportador-injetora de elétrons. Os dispositivos apresentaram eletroluminescência EL em quase toda a faixa do espectro visível, com máximos na região do ciano, para o copolímero R55 e na região do verde, para o copolímero p37. Baseado no mecanismo de Forster de transferência de energia, concluímos que os filmes desses polímeros estatísticos comportam-se como sistema hospedeiro-hóspede, devido a sobreposição parcial dos espectros de absorção e emissão dos polímeros, ocorrendo a transferência dos excitons-singletos dos segmentos de maior gap para os de menor gap, e, assim, o deslocamento dos centros emissivos para o vermelho e o aumento da eficiência dos dispositivos. / In order to improve the efficiency of polymeric light-emitting devices one of the techniques used is the conjugation confinement, decreasing the losses of energy in quenching sites, such as chain ends, defects or impurities. Moreover, the quantum confinement allows control the emissive wavelength of these materials. One of the confinement mechanisms is the copolymerization, which conjugated blocks are inserted as side groups in the main chain or non-conjugated spacers are inserted along the conjugated main chain, limiting the conjugation length. This study aimed synthesize and study the properties of random copolymers containing segments with different conjugation degrees randomly distributed in the chain and limited by no conjugated segments, and the study of the behaviour of these materials as active layer in a light emitting devices (PLEDs). To obtain random copolymers of poly [bis (fenilenovinileno)-stat-(1,8-bis-(2,6-dioximetano- 1, 4 - fenilenovinileno)-dioxioctano) -1,4-phenylene) (RBPV-DODM - PPV) have been used the Wittig route, from monomers: terephtaldeyde (a dialdeyde completely conjugated), 1.8 - bis (4 - formyl - 2.6 - dimethoxiphenoxi) octane (a dialdeyde interspaced by a saturated chain of eight methylene) and dichloride of 1.4 - a (triphenylphosphoniomethil) benzene. Three molars reasons x: y of dialdeydes monomers were used to synthesize the random polymers, obtaining various proportions and sizes of conjugated segments randomly distributed in the polymer chains. Infrared (IR) and ultravioletvisible (UVvis)spectroscopies, hydrogen nuclear magnetic resonance (1HNMR) spectrometry and differential scanning calorimetry(DSC) were used to characterize the prepared copolymersstructures. Polymers molecular weights were determined by gel permeation chromatography (GPC). The physical-chemical properties of these materials were analyzed by the molars reasons x: y used in the synthesis. And a statistical study was conducted to ascertain the probability of distribution of the various conjugated segments along the chain by these reasons. A study of the morphology and thickness of the polymer films as a function of the parameters of deposition was conducted in order to find out the best conditions to obtain homogeneous films with thickness in the order of 20 to 60 nm, necessary to achieve the best efficiencies in the polymer light emitting diode (PLEDs). For the manufacture of PLEDs ITO and Al were used as anode and cathode respectively, and a layer of 20nm of the statistical polymer as active matrix and electroluminescent. To facilitate the transport of charge carriers, layers of PEDOT: PSS and BPBD were placed between the film and polymer electrodes. Tests were also carried out with films of the molecule Alq-3 as layer electron carrier / injector. The devices had electroluminescence EL in almost the entire range of the visible spectrum, with maximum in the region of cyan, for the copolymer R55 and in the green, for the copolymer p37. Based on the Forster mechanism of energy transfer, we find that the films of these statistical polymers behave themselves as host-guest system, due to partial overlap of absorption and emission spectra of the polymers, occurring the transfer of excitons-singletes of the segments with largest gap for the smaller gap, and thus the displacement of the emission centers for the red.

No description available.