The facile synthesis of engineering thermoplastics enabled the development of structure-morphology-property relationships for a wide range of applications. Utilizing step-growth polymerization techniques, a myriad of reaction conditions probed various polymer families including polysulfones, polyesters, polyimides and polyureas. Copolymers ranging from random to segmented sequences provided insight into the influence of segment length on physical properties. Melting temperatures, glass transition temperatures, and mechanical properties responded systematically to segment length and morphology. Leveraging several complementary analytical techniques identified critical segment lengths required for phase separation and crystallization within these copolymers. Introduction of hydrogen bonding further complicated the interrelationships between thermal and mechanical properties, and possible co-crystallization between dissimilar segments occurred. Finally, branching out from linear copolymers to other topologies determined the influence of branch length on rheological and mechanical properties. The commercially-viable synthesis of these various thermoplastics further highlights the immediate impact on state-of-the-art materials, and the fundamental development described herein provides a road map for future development in this field. / Ph. D.

This investigation was conducted to explore the between trial variability of the measures of the isometric peak force, time to peak force, area to peak force, area under the curve, slope (20%-80%), and the average slope of subjects assigned to perform a series of four isometric grip strength contractions and to develop a discriminant function equation that would predict group membership. Forty-nine college students were instructed to perform either a series of four maximal voluntary contractions (sincere) or a series of four submaximal (deceptive) contractions. The subjects were retested 24-48 hours after the initial test session. Data from both test sessions were recorded, displayed, and analyzed using segmental curve analysis. The coefficients of variation were computed for each test variable. The grand mean coefficient of variation for the sincere condition was .31 ± .02 compared to the grand mean coefficient of variation for the deceptive condition which was .77 ± .11 (p < .01). Coefficients of variation were used to predict group membership. The prediction equation accurately classified 92% of the sincere condition and 64% of the deceptive condition. / Master of Science

Non-covalent intermolecular interactions play a large role in determining the properties of a given system, from segmented copolymers to interactions of functionalized polymers with non-viral nucleic acids delivery vehicles. The ability to control the intermolecular interactions of a given system allow for tailoring of that system to yield a desired outcome, whether it is a copolymers mechanical properties or the colloidal stability of a pDNA-delivery vector complex. Each chemical system relies on one or more types of intermolecular interaction such as hydrogen bonding, cooperative À-À stacking, electrostatic interactions, van der waals forces, metal-ligand coordination, or hydrophobic/solvophobic effects. The following research describes the tailoring of specific intermolecular interactions aimed at altering the physical properties of segmented copolymers and non-viral gene delivery vectors. Amide containing segmented copolymers relies heavily on hydrogen bonding intermolecular interactions for physical crosslinking to impart the necessary microphase separated morphology responsible for a copolymers physical properties. Amide containing hard segments are composed of various chemical structures from crystalline aramids to amorphous alkyl amides with each structure possessing unique intermolecular interactions. Variations to either of the copolymer segments alters the copolymers physical properties allowing for tuning of a copolymers properties for a particular application. The synthetic strategies, structure-property relationships, and physical properties of amide containing segmented copolymers are thoroughly reported in the literature. Each class of segmented copolymer that contain amide hydrogen bonding groups exhibits a wide range of tunable properties desirable for many applications. The segmented copolymers discussed here include poly(ether-block-amide)s, poly(ether ester amide)s, poly(ester amide)s, poly(oxamide)s, PDMS polyamides, and polyamides containing urethane, urea, or imide groups. The structure-property relationships (SPR) of poly(oxamide) segmented copolymers is not well understood with only one report currently found in literature. The effects of oxamide spacing in the hard segment and molecular weight of the soft segments in PDMS poly(oxamide) segmented copolymers demonstrated the changes in physical properties associated with minor structural variations. The optically clear PDMS poly(oxamide) copolymers possessed good mechanical properties after bulk polymerization of ethyl oxalate terminated PDMS oligomers with alkyl diamines or varied length. FTIR spectroscopy experiments revealed an ordered hydrogen bonding carbonyl stretching band for each copolymer and as the spacing between oxamide groups increased, the temperature at which the hard segment order was disrupted decreased. The increased spacing between oxamide groups also led to a decrease in the flow temperature observed with dynamic mechanical analysis. Copolymer tensile properties decrease with increased oxamide spacing as well as the hysteresis. The structure-property investigations of PDMS poly(oxamide) segmented copolymers showed that the shortest oxamide spacing resulted in materials with optimal mechanical properties. A new class of non-chain extended segmented copolymers that contained both urea and oxamide hydrogen bonding groups in the hard segment were synthesized. PDMS poly(urea oxamide) (PDMS-UOx) copolymers displayed thermoplastic elastomer behavior with enhanced physical properties compared to PDMS polyurea (PDMS-U) controls. Synthesis of a difunctional oxamic hydrazide terminated PDMS oligomer through a two-step end capping procedure with diethyl oxalate and hydrazine proved highly efficient. Solution polymerization of the oxamic hydrazide PDMS oligomers with HMDI afforded the desired PDMS-UOx segmented copolymer, which yielded optically clear, tough elastomeric films. Dynamic mechanical analysis showed a large temperature insensitive rubbery plateau that extended up to 186 ÚC for PDMS-UOx copolymers and demonstrated increased rubbery plateau ranges of up to 120 ÚC when compared to the respective PDMS-U control. The increase in thermomechanical properties with the presence of oxamide groups in the hard segment was due to the increased hydrogen bonding, which resulted in a higher degree of microphase separation. DMA, SAXS, and AFM confirmed better phase separation of the PDMS-UOx copolymers compared to PDMS-U controls and DSC and WAXD verified the amorphous character of PDMS-UOx. Oxamide incorporation showed a profound effect on the physical properties of PDMS-UOx copolymers compared to the controls and demonstrated promise for potential commercial applications. Two novel segmented copolymers based on a poly(propylene glycol) (PPG) that contained two or three oxamide groups in the hard segment were synthesized. Synthesis of non-chain extended PPG poly(trioxamide) (PPG-TriOx) and PPG poly(urea oxamide) (PPG-UOx) segmented copolymers utilized the two-step end-capping procedure with diethyl oxalate and hydrazine then subsequent polymerization with oxalyl chloride or HMDI, respectively. The physical properties of the PPG-TriOx and PPG-UOx copolymers were compared to those of PPG poly(urea) (PPG-U) and poly(oxamide) (PPG-Ox) copolymers. FTIR studies suggested the presence of an ordered hydrogen bonded hard segment for PGG-TriOx and PPG-Ox copolymers with PPG-TriOx possessing a lower energy ordered hydrogen bonding structure. PPG-UOx copolymers exhibited a larger rubbery plateau and higher moduli compared to PPG-U copolymers and also a dramatic increase in the tensile properties with the increased hydrogen bonding. The described copolymers provided a good example of the utility of this new step-growth polymerization chemistry for producing segmented copolymers with strong hydrogen bonding capabilities. Non-viral nucleic acid delivery has become a hot field in the past 15 years due to increased safety, compared to viral vectors, and ability to synthetically alter the material properties. Altering a synthetic non-viral delivery vector allows for custom tailoring of a delivery vector for various therapeutic applications depending on the target disease. The types of non-viral delivery vectors are diverse, however the lack of understanding of the endocytic mechanisms, endosomal escape, and nucleic acid trafficking is not well understood. This lack of understanding into these complex processes limits the effective design of non-viral nucleic acid delivery vehicles to take advantage of the cellular machinery, as in the case of viral vectors. Mechanisms for cellular internalization of polymer-nucleic acid complexes are important for the future design of nucleic acid delivery vehicles. It is well known that the mammalian cell surface is covered with glycosaminoglycans (GAG) that carry a negative charge. In an effort to probe the effect of GAG charge density on the affinity of cationic poly(glcoamidoamine) (PGAA)-pDNA complexes, quartz crystal microbalance was employed to measure the mass of GAGs that associated with a polyplex monolayer. Affinity of six different GAGs that varied in the charge density were measured for polyplexes formed with poly(galactaramidopentaethylenetetramine) (G4) cationic polymers and pDNA. Results showed that the affinity of GAGs for G4 polyplexes was not completely dependent on the electrostatic interactions indicating that other factors contribute to the GAG-polyplex interactions. The results provided some insight into the interactions of polyplexes with cell surface GAGs and the role they play in cellular internalization. Two adamantane terminated polymers were investigated to study the non-covalent inclusion complexation with click cluster non-viral nucleic acid delivery vehicles for passive targeting of the click cluster-pDNA complexes (polyplex). Incorporation of adamantyl terminated poly(ethylene glycol) (Ad-PEG) and poly(2-deoxy-2-methacrylamido glucopyranose) (Ad-pMAG) polymers into the polyplex formulation revealed increased colloidal stability under physiological salt concentrations. Ad-pMAG polyplexes resulted in lower cellular uptake for HeLa cells and not two glioblastoma cell lines indicating the pMAG corona imparts some cell line specificity to the polyplexes. Ad-pMAG provided favorable biological properties when incorporated into the polyplexes as well as increased polyplex physical properties. / Ph. D.

This dissertation describes a general synthetic platform for segmented polymers that have main-chain reversible linkages based on cyclopentadiene-maleimide Diels-Alder chemistry. Research in the area of thermally reversible (self-healing) polymers has been an ever-expanding area of interest in the current scientific literature. However most of the emphasis has been on systems containing furan-maleimide linkages. While inexpensive and synthetically accessible, furan chemistry is mostly limited to crosslinked and hyperbranched architectures due to its relatively weak binding with maleimides at suitable propagation temperatures. Following a general review of the literature in this area (Chapter 1) the first stage of our research (Chapter 2) entails the synthesis of 2-substituted hydroquinones, which are needed as monomers in the later stages. The novelty of our hydroquinone synthesis stems from the use of allylic and other alkenyl ethers as the source of the ring substituent, and from the utilization of catalytic hydroboration to improve atom-efficiency. We showed that hydroquinones with widely varying functionality can be prepared efficiently by our method; these findings were published in the journal Tetrahedron in 2018. The second stage (Chapter 3) involves the use of the new hydroquinones in step-growth syntheses of hydroquinone-terminated telechelic and chain-extension of these telomers via Diels-Alder chemistry to form segmented polymers having thermally reversible linkages. The novelty of our approach rests with the use of cyclopentadiene-maleimide chemistry for the linkages, while the overall physical properties such as the glass transition temperature were established by using well-defined aromatic polymers — poly(ether ether ketones) or PEEK and poly(aryl ether sulfones) or PAES — as segments. This approach represents an important departure from earlier work in our group in which reversible linkages were present in every repeat unit of a step-growth Diels-Alder polymer that showed thermal reversibility in solution but not in the bulk, owing to glass transition temperatures that were too high. Using scratch-healing and mechanical (tensile) tests, we show that our new segmented polymers exhibit self-healing characteristics that are competitive with or superior to previously reported systems based on different Diels-Alder chemistry. The third stage (Chapter 4) aims to explore new application areas for some of the more novel functionalized hydroquinones reported in Chapter 2. First we developed an efficient synthesis of a PAES derivative bearing 5-phenoxypentyl groups on the hydroquinone moiety. Then we showed that the 5-phenoxy group can be cleanly cleaved, post-polymerization, to afford a PAES having 5-bromopentyl substituents. The promise of our method rests with the potential of the pendant electrophiles to undergo reactions with nucleophilic reagents to post-modify these polymers further. As proof of concept, we showed that substitution of the pendant bromides with furfuryloxy groups enabled thermally reversible crosslinking with a bis-maleimide reagent to form a polymeric material that demonstrates partial scratch healing. Finally we are exploring the synthesis of new ion-containing polymers by substituting the pendant bromides with tertiary amines. / PHD / This dissertation describes a new synthetic approach to polymeric materials that can heal themselves (for example, repair small cracks that may have formed due to stress or aging) simply by heating the damaged area. Our approach uses a thermally reversible chemical reaction (called the Diels-Alder reaction) to connect several shorter polymer segments into longer chains. Upon heating, the segments can come apart, diffuse into and through the damaged area, and then rejoin. The first chapter is a review of background in the published literature as well as previous not-yet-published work in our laboratory. The second chapter describes the creation of new building-block molecules (monomers) that will help control the temperature range necessary to induce self-healing after incorporation into the polymer segments. The third chapter details the process of forming the segments, the incorporation of self-healing functionalities on the ends of the segments, the joining of the segments into longer polymeric chains, and the testing of all of the physical properties of these new materials, including their self-healing capabilities. The fourth chapter represents a preliminary study of a new method of preparing ion-containing polymers. The latter materials have potential use in various membrane technologies including fuel cell devices for the harnessing of renewable energy.

The synthesis and characterization of a variety of ammonium ionenes from water-soluble coatings to high-performance elastomers are discussed. Water-soluble random copolymer ionenes were synthesized using the Menshutkin reaction from 1,12-dibromododecane, N,N,Nâ ²,Nâ ²-tetramethyl-1,6-hexanediamine, and 1,12-bis(N,N-dimethylamino)dodecane. The absolute molecular weights were determined for the first time using a multiangle laser light scattering detector in aqueous size exclusion chromatography and the weight-average molecular weights of these ionenes were in the range of 17,000-20,000 g/mol. Charge density increased with increasing molar ratio of N,N,Nâ ²,Nâ ²-tetramethyl-1,6-hexanediamine and the glass transition temperature (Tg) increased from 69 °C to 90 °C as the charge density increased. Small angle x-ray scattering (SAXS) showed isotropic scattering patterns for these ionenes. A limited study on cytotoxicity of these ionenes showed no direct correlation between charge density and cell viability for human brain microvascular endothelial cell line. A series of low hard segment (HS) content, poly(propylene glycol) (PPG)-based ammonium ionenes were synthesized using a Menshutkin reaction from bromine end-capped PPG oligomers (prepared using acid-chloride reactions) and N,N,Nâ ²,Nâ ²-tetramethyl-1,6-hexanediamine. Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry, titration analyses, and ¹H NMR spectroscopy, confirmed the difunctionality of bromine end-capped PPG oligomers. Thermal analysis revealed Tg's of -60 °C, comparable to pure PPG, using differential scanning calorimetery (DSC), dynamic mechanical analysis (DMA) confirming microphase separation, and an onset of degradation (Td) at 240 °C. Synthesis of a series of random block copolymer ammonium ionenes with an aliphatic 1,12-dibromododecane as part of the hard segment (33 wt% HS) enhanced film formation and supported microphase separation property. The Td and Tg did not change compared to PPG-ionenes with lower HS content. DMA and tensile testing demonstrated the influence of soft segment (SS) molecular weight and hard segment (HS) content on the mechanical properties of segmented ammonium ionenes. DMA showed the onset of flow, ranging from 100-140 ºC for 1K and 2K g/mol PPG-based ionenes respectively. SAXS revealed a Bragg distance scaled with soft segment molecular weight and ranged from 6.6 to 23.4 nm for 1K to 4K g/mol PPG-based ionenes, respectively. An investigation of the salt-responsive solubility property of random block copolymer PPG-ionenes revealed a dependence on PPG molecular weight. The 1K g/mol PPG-based ionenes with a hydrophilic (HPL)/hydrophobic (HPB) value ranging from one to three showed solubility in both water and one wt% NaCl aqueous solutions. The 2K g/mol PPG-based ionenes containing HPL/HPB value of two to 15 showed cloudy dispersions in water and one wt% NaCl solutions. The 4K g/mol PPG-based ionenes possessed the salt-responsive character; 4K g/mol PPG-based ionenes with HPL/HPB values of one to 12 showed milky dispersions in water, suspended particles in one wt% NaCl solutions and film precipitation at a HPL/HPB molar ratio of 19. / Master of Science

This thesis presents the first research on polymer-segmented-cladding-fibre (PSCF), an emerging class of microstructured- optical-fibres (MOFs), which allows single-mode operation with ultra-large-core area. This research covers the modelling, design, fabrication and experiment of the polymer optical cross-fibre (4-period-SCF) whose cross-sectional view resembles a cross. A new wedge waveguide model has been formulated and applied to demonstrate that for any given parameters, the cross fibre gives the same performance for single-mode operation as the N-period-SCFs (for N = 2, 6 and 8). These fibres behave identically if the high-index segment angle, θ1, is the same and the low-index segment angular width, θ2, is sufficiently large for negligible adjacent mode coupling effects. This remarkable finding has significant ramifications for SCF fabrication, design and performance. Theoretical predictions confirmed by experiments demonstrated that a cross-fibre is all that needed to fabricate a large-core single-mode-fibre with no geometry-induced birefringence. The high-index outer ring effects on the cross fibre single-mode performance have been systematically investigated for the first time. The study reveals that the ring index value higher than its core index has very strong effects on single-mode performance. Within a narrow range of θ1, the minimum fibre length required for single-mode operation is reduced but outside this angle range, longer single-mode length is required. Furthermore, the fibre can be anti-guiding if θ1 exceeds the cutoff angle. Incorporating the fabrication constraints, the optimal cross-fibre design with high-index ring is achieved by optimising the relative index difference, high-index segment angle and core-cladding diameter ratio. Two preform-making techniques developed for the cross-fibres fabrication include the cladding-segment-in-tube method and the core-cladding-segment-in-tube method. The innovative approach in these methods overcomes the problems of bubble formation and fractures, which are related to the fibre structure complexity and the polymer intrinsic properties and their processing. It enables the successful drawing of single-mode fibres. This thesis reports the first experimental demonstration of single-mode operation of large-core cross-fibre. Three experimental studies with different cross-fibre designs have demonstrated (i) large-core single-mode operation, (ii) high-index ring effects on fibre performance and (iii) cross-fibre optimal design trial. Apart from this, the 8-period-SCF fibre performance has been demonstrated experimentally.

This thesis presents the first research on polymer-segmented-cladding-fibre (PSCF), an emerging class of microstructured- optical-fibres (MOFs), which allows single-mode operation with ultra-large-core area. This research covers the modelling, design, fabrication and experiment of the polymer optical cross-fibre (4-period-SCF) whose cross-sectional view resembles a cross. A new wedge waveguide model has been formulated and applied to demonstrate that for any given parameters, the cross fibre gives the same performance for single-mode operation as the N-period-SCFs (for N = 2, 6 and 8). These fibres behave identically if the high-index segment angle, θ1, is the same and the low-index segment angular width, θ2, is sufficiently large for negligible adjacent mode coupling effects. This remarkable finding has significant ramifications for SCF fabrication, design and performance. Theoretical predictions confirmed by experiments demonstrated that a cross-fibre is all that needed to fabricate a large-core single-mode-fibre with no geometry-induced birefringence. The high-index outer ring effects on the cross fibre single-mode performance have been systematically investigated for the first time. The study reveals that the ring index value higher than its core index has very strong effects on single-mode performance. Within a narrow range of θ1, the minimum fibre length required for single-mode operation is reduced but outside this angle range, longer single-mode length is required. Furthermore, the fibre can be anti-guiding if θ1 exceeds the cutoff angle. Incorporating the fabrication constraints, the optimal cross-fibre design with high-index ring is achieved by optimising the relative index difference, high-index segment angle and core-cladding diameter ratio. Two preform-making techniques developed for the cross-fibres fabrication include the cladding-segment-in-tube method and the core-cladding-segment-in-tube method. The innovative approach in these methods overcomes the problems of bubble formation and fractures, which are related to the fibre structure complexity and the polymer intrinsic properties and their processing. It enables the successful drawing of single-mode fibres. This thesis reports the first experimental demonstration of single-mode operation of large-core cross-fibre. Three experimental studies with different cross-fibre designs have demonstrated (i) large-core single-mode operation, (ii) high-index ring effects on fibre performance and (iii) cross-fibre optimal design trial. Apart from this, the 8-period-SCF fibre performance has been demonstrated experimentally.

La recherche de signes de vie extraterrestre par l'observation et la caractérisation d'exoplanètes est, entre autres, l'un des enjeux majeurs de l'astrophysique moderne. Cette quête se traduit de manière instrumentale par le développement de télescopes fournissant des résolutions angulaires supérieures à celles obtenues à l'heure actuelle. C'est pourquoi les projets de futurs très grands télescopes font usage de miroirs primaires dépassant les 30 mètres de diamètre. Leur conception est alors inévitablement basée, pour des raisons techniques et technologiques, sur une géométrie segmentée. De ce fait, la segmentation du miroir primaire implique une complexification des structures pupillaires du télescope. Dans le but d'atteindre les niveaux de qualité optique nécessaires aux applications scientifiques visées, la prise en compte et la correction des effets introduits par un mauvais alignement des segments est de prime importance puisque la résolution angulaire d'un télescope non cophasé serait équivalente à celle obtenue avec un segment individuel. Dans ce contexte, je développe dans cette thèse deux analyseurs de cophasage permettant de mesurer et de corriger les aberrations de piston, tip et tilt présentes sur une pupille segmentée. Le premier, nommé Self-Coherent Camera - Phasing Sensor (SCC-PS), est basé sur une analyse du signal en plan focal. Le second, nommé ZELDA - Phasing Sensor (ZELDA-PS), repose quant à lui sur une analyse du signal en plan pupille. Sont présentés dans ce manuscrit les résultats obtenus à l'aide de simulations numériques ainsi que ceux issus de l'implémentation de la SCC-PS sur un banc d'optique d'essai. / Searching for extraterrestrial life through the observation and characterization of exoplanets is, amongst others, one of the major goal of the modern astrophysics. This quest translate from an instrumental point of view to the development of telescope capable of reaching higher angular resolution that what is actually ongoing. That is why the future projects of extremely large telescopes are using primary mirrors exceeding the 30 meters in diameter. Their conception is consequently based, for technical and technological reasons, on a segmented geometry. The segmentation of the primary mirror therefore implies a growing complexity of the structure of its pupil. In order to reach the optical quality required by the sciences cases of interest, taking into account and correct for the effects introduced by a poor alignment of the segments is mandatory, as the angular resolution of a non-cophased telescope is equivalent to the one obtained with a single segment. In this context, I develop in this manuscript two cophasing sensors allowing to measure and correct for the aberrations of piston, tip and tilt present on a segmented pupil. The first one, the Self-Coherent Camera - Phasing Sensor (SCC-PS), is based on a focal plane analysis of the signal. The second one, the ZELDA - Phasing Sensor (ZELDA-PS), is based on a pupil plane analysis of the signal. The results obtained by means of numerical simulations and the first results coming from the implementation of the SCC-PS on an optical bench are presented in this manuscript.

O presente trabalho teve por objetivo estimar parâmetros genéticos de características de carcaça medidas por ultra-sonografia e de desenvolvimento ponderal em bovinos da raça Santa Gertrudis. O conjunto de dados é proveniente de 12 fazendas participantes do Programa de Melhoramento Animal da ABSG. As características analisadas foram, área de olho de lombo, espessura de gordura subcutânea, peso ao nascimento, peso aos 120 dias de idade, peso a desmama, peso aos 12 meses de idade, peso aos 18 meses de idade, peso aos 24 meses de idade e perímetro escrotal aos 18 meses de idade. Os dados foram pré-ajustados para o efeito de idade pela metodologia de polinômios segmentados. Os componentes de (co)variância foram estimados por máxima verossimilhança restrita utilizando-se o software MTDFREML. As estimativas de herdabilidade foram obtidas em análises uni-característica, e em análises bi-características, as quais geraram estimativas de correlações genéticas das características de AOL, EGS com as características de desempenho ponderal. As estimativas de herdabilidade para AOL e EGS foram de 0,23±0,10 e 0,05±0,04, respectivamente. Os parâmetros encontrados neste trabalho são estimativas para uma amostra da população da raça Santa Gertrudis e sugerem-se estudos adicionais, para confirmar as estimativas de parâmetros genéticos para estimativas de carcaça obtidas por ultra-sonografia, para esta raça. / The present study has as objectives to estimate genetic parameters of carcass traits measured by ultrasound and traits of ponderal development in Santa Gertrudis beef cattle. All data set evaluated was originated from 12 farms participating of the Animal Breeding Program conduced by Grupo de Melhoramento Animal of the Universidade de Sao Paulo. The traits analyzed were rib eye area (REA), fat thickness (FAT), birth weight, weight at 120 days, weaning weight, weight at 12, 18 and 24 months and scrotal circumference at 18 months of age. The data were pre-adjusted for age effect by segmented polynomials methodology. The co-variance components were estimated by Restricted Maximum Likelihood using the MTDFREML software. The estimates of heritability were obtained from univariate analysis, while the genetic correlations between REA and FAT with traits of ponderal development were calculated from bivariate analysis. The heritability estimated for REA and FAT were of 0.23±0.10 and 0.05±0.04, respectively. All genetic parameters reported in this present study are estimated from a population sampling of Santa Gertrudis animals, being suggested additional research for genetic parameters evaluation of carcass traits measured by ultrasound. In the breed.

Este trabalho propõe uma visão sobre as fotografias publicadas por G Magazine, revista brasileira voltada para o público gay. A perspectiva é identificar o discurso estruturado na linguagem de corpos-signos do nu masculino. A partir de conceitos sobre a comunicação na contemporaneidade, noções de sexualidade apresentadas por Foucault, Freud e Lacan, e de imagem e fotografia para Dubois, Barthes e Peirce, estabeleceremos o paralelo entre os registros lacanianos e as categorias peirceanas. A disposição anatômica dos corpos-signos constrói um discurso conservador sobre a posição do masculino no sistema, concedendo a este o lugar do exercício e manifestação de poder. / This paper proposes a view on the photography published by G Magazine, a Brazilian magazine focused on the gay public. The perspective is to identify the discourse built on the language of naked male body-signs. Based on concepts about the contemporary communication, notions on sexuality stated by Foucault, Freud and Lacan, and on image and photography by Dubois, Barthes and Peirce, we establish a parallel between Lacans registers and Peirces categories. The anatomic disposition of the body-signs constructs a conservative discourse on systems male position, providing the main role of practice and manifestation of power.