Synthesis and photochromic behavior of some azo-polysiloxanes modified with nucleobases or donor-acceptor groups

Enea, Ramona; Resmeriță, Ana-Maria; Petraru, Laura; Grigoraş, Cristian; Scutaru, Dan; Simionescu, C. I.; Hurduc, Nicolae

doi:10.2478/s11532-007-0042-8

Cited by 5 publications

(3 citation statements)

References 24 publications

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“…Hurduc et al51, 52 utilized the same reaction conditions Sedlak et al used to functionalize an azopolysiloxane with either adenine, thymine, uracil, or cytosine as shown in Figure 8. The resulting nucleobase‐functionalized azopolysiloxanes were thermally more stable than the precursor53 and the authors investigated the photoisomerizations of the azobenzene in the resulting polysiloxanes 51, 54. Hurduc and coworkers54 demonstrated that the nucleobase‐functionalized polysiloxanes exhibited slower cis‐trans relaxation kinetics after UV trans‐cis isomerization which they attributed to the decreased mobility of the polymer chains resulting from the self‐complementary hydrogen bonding between the nucleobases.…”

Section: Nucleobase‐functionalized Polysiloxanesmentioning

confidence: 99%

DNA‐Inspired Hierarchical Polymer Design: Electrostatics and Hydrogen Bonding in Concert

Hemp¹,

Long²

2011

Macromolecular Bioscience

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Nucleic acids and proteins, two of nature's biopolymers, assemble into complex structures to achieve desired biological functions and inspire the design of synthetic macromolecules containing a wide variety of noncovalent interactions including electrostatics and hydrogen bonding. Researchers have incorporated DNA nucleobases into a wide variety of synthetic monomers/polymers achieving stimuli-responsive materials, supramolecular assemblies, and well-controlled macromolecules. Recently, scientists utilized both electrostatics and complementary hydrogen bonding to orthogonally functionalize a polymer backbone through supramolecular assembly. Diverse macromolecules with noncovalent interactions will create materials with properties necessary for biomedical applications.

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Section: Nucleobase‐functionalized Polysiloxanesmentioning

confidence: 99%

DNA‐Inspired Hierarchical Polymer Design: Electrostatics and Hydrogen Bonding in Concert

Hemp¹,

Long²

2011

Macromolecular Bioscience

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“…The azopolymers were synthesized in two steps by nucleophilic substitution of chlorobenzyl groups with the sodium salt of 4-(phenylazo) phenol or 2,4-dinitrophenol as shown in Figure 1. More details concerning polymer synthesis can be found in our previous reports [29,30]. All polymers were characterized by 1 H-NMR, differential scanning calorimetry (DSC), UV spectroscopy and surface contact angle measurements.…”

Section: Experimental Partmentioning

confidence: 99%

Rigid and flexible azopolymers modified with donor/acceptor groups. Synthesis and photochromic behavior

Luca¹,

Rocha²,

Resmeriță³

et al. 2011

Express Polym. Lett.

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Azobenzene-containing polymers have received increasing attention due to their unique properties allowing various applications, such as in micro-fluidic or in membrane based separation systems, to optically change the materials surfaces wettability [1][2][3][4][5], in biology, to generate photosensitive micellar systems for drug delivery purposes, for example [6,7], in optics or optoelectronics, to generate optical switching and data storage functions [8][9][10][11][12][13]. The distinct properties of these materials are attributed to the photo-isomerization of azobenzene molecules which undergo reversible trans-cis isomerization of the double bond [14], under external stimuli. It should be emphasized that isomerization of the azobenzene is accompanied by large changes in both geometry and dipole moment [15][16][17][18][19]. These photo responsive properties are determined by both azo-chromophore structure and polymeric architecture. One of the most interesting applications is connected to the possibility to induce a certain type of relief on the surface of azo-polymeric film, by laser irradiation, [20][21][22]. This surface nano-structura- Abstract. The aim of this work is to investigate the photochromic behavior and nano-structuration capacity of azo-polymers with different architectures and main chain flexibilities, modified with donor/acceptor groups. As a function of the chemical structure and the substitution degree, the azo-polymers can generate physical interactions and lead to different polymer chain conformational re-organization under optical excitation. Nano-structuration experiments were performed on samples with different chemical structures. Surface relief gratings have been realized both in poly(chloromethyl styrene) and polysiloxanes polymers. The complexity of the phenomena that take place under optical excitation of the azo-benzene molecules are reflected by the samples behavior during the nano-structuration process. Preliminary tests to determine the ability of the azo-polysiloxanic films to support cell growth were performed. The films showed remarkable properties to sustain both cell adhesion and proliferation.

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“…A further increase in flexibility can be obtained by introducing not only the styrene, but a co-monomer (for example butyl acrylate) in the graftedchains. The second application refers to the use of the star-or brush-polysiloxanes as precursors obtaining azo-materials for optoelectronics and biology [21,22]. For this purpose, the chloromethyl styrene may be used as monomer, or co-monomer in ATRP grafting reactions.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of star and brush grafted polysiloxanes, obtained by atom transfer radical polymerization

et al. 2008

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Star-and brush-polysiloxanes were synthesized via living radical polymerization using two different catalytic systems. The new compounds were characterized by 1 H-NMR, gel permeation chromatography (GPC) and differential scanning calorimetry (DSC) techniques. CuCl and 2,2'-bipyridyl proved to be the most efficient catalytic system. The type of catalytic system and the reaction conditions control the number of arms for star polymers or the grafted-chain density for brush polymers. The use of chloromethyl styrene as monomer or co-monomer yields homogeneous star-or brush-polysiloxanes, although chloromethyl styrene is an inimer system. The homogeneity of materials was verified by GPC and DSC (TOPEM) methods. For linear grafted polysiloxanes the molecular simulations reflect a tendency of chains to adopt globular conformation for high values of the branching density. The polysiloxanes grafted with styrene/chloromethyl styrene were modified with azobenzene in order to obtain systems able to react to the light stimuli. Rheological behavior of the polymer solutions were evaluated before and after irradiation with UV light. After the UV irradiation a significant viscosity increase was evidenced.

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Synthesis and photochromic behavior of some azo-polysiloxanes modified with nucleobases or donor-acceptor groups

Cited by 5 publications

References 24 publications

DNA‐Inspired Hierarchical Polymer Design: Electrostatics and Hydrogen Bonding in Concert

DNA‐Inspired Hierarchical Polymer Design: Electrostatics and Hydrogen Bonding in Concert

Rigid and flexible azopolymers modified with donor/acceptor groups. Synthesis and photochromic behavior

Synthesis and characterization of star and brush grafted polysiloxanes, obtained by atom transfer radical polymerization

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