Crystallization of Poly(γ-benzyl<scp>l</scp>-glutamate) in Thin Film Solutions: Structure and Pattern Formation

Jahanshahi, Kaiwan; Botiz, Ioan; Reiter, Renate; Thomann, Ralf; Heck, Barbara; Shokri, Roozbeh; Stille, W.; Reiter, Günter

doi:10.1021/ma3024602

Cited by 20 publications

(28 citation statements)

References 33 publications

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“…8). The first peak can be assigned to a d-spacing of 1.3-1.4 nm corresponding to a pseudo-hexagonal packing of helices, 50,63,64 while the second 'peak', or shoulder, corresponds to the 0.5 nm helical pitch; 50 this indicates that P(BLG x -co-AG 1−x ) n -dioxane and PBLG 51 -dioxane aggregates have a similar microstructure. This result suggests that homopolymer PBLG 51 and statistical copolymer P(BLG x -co-AG 1−x ) n can both self-assemble in a similar fashion, that is pseudo-hexagonal packing of α-helices.…”

Section: Mechanism Of Photo-crosslinking Gelationmentioning

confidence: 99%

Fibrillar gels via the self-assembly of poly(l-glutamate)-based statistical copolymers

et al. 2015

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Polypeptides having secondary structures often undergo self-assembly which can extend over multiple length scales. Poly(γ-benzyl-L-glutamate) (PBLG), for example, folds into α-helices and forms physical organogels, whereas poly(L-glutamic acid) (PLGA at acidic pH) or poly(L-glutamate) (PLG at neutral/basic pH) do not form hydrogels. We explored the gelation of modified PBLG and investigated the deprotection of the carboxylic acid moieties in such gels to yield unique hydrogels. This was accomplished through photo-crosslinking gelation of poly(γ-benzyl-L-glutamate-co-allylglycine) statistical copolymers in toluene, tetrahydrofuran, and 1,4-dioxane. Unlike most polymer-based chemical gels, our gels were prepared from dilute solutions (<20 g L −1 , i.e., <2% w/v) of low molar mass polymers. Despite such low concentrations and molar masses, our dioxane gels showed high mechanical stability and little shrinkage; remarkably, they also exhibited a porous fibrillar network. Deprotection of the carboxylic acid moieties in dioxane gels yielded pH responsive and highly absorbent PLGA/PLG-based hydrogels (swelling ratio of up to 87), while preserving the network structure, which is an unprecedented feature in the context of crosslinked PLGA gels. These outstanding properties are highly attractive for biomedical materials.

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Section: Mechanism Of Photo-crosslinking Gelationmentioning

confidence: 99%

Fibrillar gels via the self-assembly of poly(l-glutamate)-based statistical copolymers

et al. 2015

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“…Details of the experimental method were introduced in a previous report. 26 In brief, a series of scattering curves were collected at several angles ω (ω is the angle between the incident beam and the sample surface plane) in the range from 1.5°to 4.5°, varying 2θ (the angle between the scattered and the incident beam) from 3°to 9°( Figure S7, Supporting Information). The intensities of the 020 peak were plotted as a function of ω (Figure 4a, inset), exhibiting a Gaussian distribution.…”

mentioning

confidence: 99%

“…To determine the orientation of the lattice planes, additional scattering experiments were performed. Details of the experimental method were introduced in a previous report . In brief, a series of scattering curves were collected at several angles ω (ω is the angle between the incident beam and the sample surface plane) in the range from 1.5° to 4.5°, varying 2θ (the angle between the scattered and the incident beam) from 3° to 9° (Figure S7, Supporting Information).…”

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confidence: 99%

Anisotropic Photophysical Properties of Highly Aligned Crystalline Structures of a Bulky Substituted Poly(thiophene)

Wang¹,

Heck

Schiefer

et al. 2014

ACS Macro Lett.

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The photophysical properties of a phenylsubstituted poly(thiophene), poly(3-(2,5-dioctylphenyl)-thiophene) (PDOPT), were studied as a function of polarization and degree of orientation of the crystalline structure. Under well-chosen controlled conditions, largesized spherulitic crystals of PDOPT were successfully prepared from the melt. From polarized optical microscopy and X-ray diffraction, the molecular orientation of PDOPT within the spherulite was determined, indicating that the fastest growth direction of the spherulite was the a-axis. This implied that crystallization of PDOPT was directed by the packing of the side chains rather than the backbones, which are significantly separated. As the crystalline lamellae were all radially oriented, the local absorbance strongly depended on the polarization of the incoming light. Compared to randomly oriented crystals in a quenched and thus rapidly crystallized sample, PDOPT spherulites displayed red-shifted absorption and emission spectra, combined with a reduced photoluminescence quantum yield. Even for these markedly separated polymer backbones (1.47 nm), the reduced photoluminescence suggests an enhancement of interchain interactions of highly ordered bulky substituted polythiophene induced by crystallization.T he optoelectronic properties of conjugated polymers are of importance for their application in organic electronic devices. 1 These properties are considerably determined by both the conformation of the chain-like molecules (intrachain arrangements of chromophores) and the way these molecules pack in the solid state (interchain arrangements of chromophores). In thin films of conjugated polymers prepared by standard techniques like spin coating, interchain energy transport is usually more rapid than intrachain transport. 2 Thus, the corresponding optoelectronic properties depend sensitively on the extent of interchain interactions. 3 It is widely accepted that interchain interactions in thin films are effectively influenced by chain aggregation and film morphology. Consequently, the relevant photophysical and electronic properties can be controlled by appropriate processing conditions. 4,5 Most previous studies have focused on conjugated polymers with short backbone stacking distances (<5 Å), such as in alkylsubstituted poly(thiophene)s (P3ATs) 5,6 or poly(phenylenevinylene)s (PPVs). 7,8 In these materials, interchain interactions are mainly determined by the overlap of π-orbitals, i.e., π−π interactions. To control interchain interactions, conjugated polymers with bulky side chains have been developed. 9 Bulky side chains can separate the polymer backbones from each other and thus may have a profound influence on the final properties of these materials. 9,10 In particular, the separation of main chains can strongly improve the photoluminescence (PL) quantum yield (Q y ) of conjugated systems. 11 Up to now, however, only a few reports have discussed the relationships between morphology and optoelectronic properties of conjugated systems having a large main c...

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“…These processes actually dictate the final properties of polymers in bulk, solutions, or thin-films [ 16 , 17 , 18 , 19 ]. Due to the potentiality to precisely control other processing parameters, such as melting, crystallization or glass-transition temperature, a polymer can display a highly tunable molecular ordering on multiple-length scales, ranging from nanometers to macroscopic dimensions that can generate a diverse landscape of nanostructures [ 16 , 20 , 21 , 22 ]. Further expansion of this landscape on the molecular, microscopic and macroscopic scales can be induced by favoring physical and chemical interactions of specific chain segments with their neighbors [ 15 , 16 , 23 ] or by degrading the phase purity through the addition of other (polymeric) components [ 24 , 25 , 26 , 27 ].…”

Section: Introductionmentioning

confidence: 99%

Antimicrobial Polymeric Structures Assembled on Surfaces

2021

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Pathogenic microbes are the main cause of various undesired infections in living organisms, including humans. Most of these infections are favored in hospital environments where humans are being treated with antibiotics and where some microbes succeed in developing resistance to such drugs. As a consequence, our society is currently researching for alternative, yet more efficient antimicrobial solutions. Certain natural and synthetic polymers are versatile materials that have already proved themselves to be highly suitable for the development of the next-generation of antimicrobial systems that can efficiently prevent and kill microbes in various environments. Here, we discuss the latest developments of polymeric structures, exhibiting (reinforced) antimicrobial attributes that can be assembled on surfaces and coatings either from synthetic polymers displaying antiadhesive and/or antimicrobial properties or from blends and nanocomposites based on such polymers.

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Crystallization of Poly(γ-benzyll-glutamate) in Thin Film Solutions: Structure and Pattern Formation

Cited by 20 publications

References 33 publications

Fibrillar gels via the self-assembly of poly(l-glutamate)-based statistical copolymers

Fibrillar gels via the self-assembly of poly(l-glutamate)-based statistical copolymers

Anisotropic Photophysical Properties of Highly Aligned Crystalline Structures of a Bulky Substituted Poly(thiophene)

Antimicrobial Polymeric Structures Assembled on Surfaces

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