Synthesis and self-assembly of diblock copolymers bearing 2-nitrobenzyl photocleavable side groups†

The light-responsive behavior in solution and in thin films of block copolymers bearing 2-nitrobenzyl photocleavable esters as side groups is discussed in this article. The polymers were synthesized by grafting 2-nitrobenzyl moieties onto poly(acrylic acid)-block-polystyrene (PAA-b-PS) precursor polymers, leading to poly(2-nitrobenzyl acrylate-random-acrylic acid)-block-polystyrene (P(NBA-r-AA)-b-PS) block copolymers. The UV irradiation of the block copolymers in a selective solvent for PS led to the formation of micelles that were used to trap hydrophilic molecules inside their core (light-induced encapsulation). In addition, thin films consisting of light-responsive P(NBA-r-AA) cylinders surrounded by a PS matrix were achieved by the self-assembly of P(NBA-r-AA)-b-PS copolymers onto silicon substrates. Exposing these films to UV irradiation generates nanostructured materials containing carboxylic acids inside the cylindrical nanodomains. The availability of these chemical functions was demonstrated by reacting them with a functional fluorescent dye. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 Light-responsive poly(2-nitrobenzyl acrylate-random-acrylic acid)-block-polystyrene (P(NBA-r-AA)-b-PS) block copolymers (P(NBA-r-AA)-b-PS) have been synthesized and further self-assembled in solution as well as in thin films. In solution, the block copolymers were used to encapsulate hydrophilic molecules inside the core of light-induced micelles. In addition, light-responsive nanostructured thin films have been prepared onto silicon substrates. Exposing these films to UV irradiation generates chemical functionalities inside the photo-responsive nanodomains. Copyright © 2011 Wiley Periodicals, Inc.

[1]  Ronald P. Manginell,et al.  Programmed Adsorption and Release of Proteins in a Microfluidic Device , 2003, Science.

[2]  Yue Zhao,et al.  Preparation of Azobenzene-Containing Amphiphilic Diblock Copolymers for Light-Responsive Micellar Aggregates , 2004 .

[3]  Sheng Dai,et al.  Thermo- and photo-responsive polymeric systems , 2009 .

[4]  D. Irvine,et al.  Functional Nanocavity Arrays via Amphiphilic Block Copolymer Thin Films , 2008 .

[5]  Y. Morishima,et al.  Preparation and characterization of a pH-responsive nanogel based on a photo-cross-linked micelle formed from block copolymers with controlled structure. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[6]  M. Lepage,et al.  MRI observation of the light-induced release of a contrast agent from photo-controllable polymer micelles , 2007, Physics in medicine and biology.

[7]  A. Ajayaghosh,et al.  Photoresists based on a novel photorearrangement of o-nitrobenzylic polymers , 1994 .

[8]  N. Rapoport.  Physical stimuli-responsive polymeric micelles for anti-cancer drug delivery , 2007 .

[9]  Zhiqun Lin,et al.  A Rapid Route to Arrays of Nanostructures in Thin Films , 2002 .

[10]  Krzysztof Matyjaszewski,et al.  Light-induced reversible formation of polymeric micelles. , 2007, Angewandte Chemie.

[11]  Patrick Theato,et al.  One is enough: influencing polymer properties with a single chromophoric unit. , 2011, Angewandte Chemie.

[12]  Sergiy Minko,et al.  Stimuli‐Responsive Porous Hydrogels at Interfaces for Molecular Filtration, Separation, Controlled Release, and Gating in Capsules and Membranes , 2010, Advanced materials.

[13]  Elsa Reichmanis,et al.  Synthesis and evaluation of copolymers of (tert-butoxycarbonyloxy)styrene and (2-nitrobenzyl)styrene sulfonates: single-component chemically amplified deep-UV imaging materials , 1992 .

[14]  Leonid Ionov,et al.  Reversible chemical patterning on stimuli-responsive polymer film: environment-responsive lithography. , 2003, Journal of the American Chemical Society.

[15]  P. Keller,et al.  Novel Photolabile Diblock Copolymers Bearing Truxillic Acid Derivative Junctions , 2011 .

[16]  Yue Zhao,et al.  A new design for light-breakable polymer micelles. , 2005, Journal of the American Chemical Society.

[17]  Yue Zhao,et al.  Photocontrollable block copolymer micelles: what can we control? , 2009 .

[18]  C. Hawker,et al.  Block Copolymer Nanolithography: Translation of Molecular Level Control to Nanoscale Patterns , 2009, Advanced materials.

[19]  V. Pillai.  Photoremovable Protecting Groups in Organic Synthesis , 1980 .

[20]  W. Hinsberg,et al.  Block copolymer based nanostructures: materials, processes, and applications to electronics. , 2010, Chemical reviews.

[21]  J. Allard,et al.  A new two-photon-sensitive block copolymer nanocarrier. , 2009, Angewandte Chemie.

[22]  Yoshihiro Ito,et al.  pH-Sensitive Gating by Conformational Change of a Polypeptide Brush Grafted onto a Porous Polymer Membrane , 1997 .

[23]  J. Penelle,et al.  Synthesis and Thin Film Characterization of Poly(styrene-block-methyl methacrylate) Containing an Anthracene Dimer Photocleavable Junction Point , 2002 .

[24]  Bin Zhao,et al.  Dually responsive aqueous gels from thermo- and light-sensitive hydrophilic ABA triblock copolymers , 2010 .

[25]  V. Abetz,et al.  Asymmetric superstructure formed in a block copolymer via phase separation. , 2007, Nature materials.

[26]  Ting Xu,et al.  Highly Oriented and Ordered Arrays from Block Copolymers via Solvent Evaporation , 2004 .

[27]  S. Minko,et al.  Microphase Separation in Thin Films of Poly(styrene-block-4-vinylpyridine) Copolymer−2-(4‘-Hydroxybenzeneazo)benzoic Acid Assembly , 2005 .

[28]  Ning Zhao,et al.  Multi-membrane hydrogel fabricated by facile dynamic self-assembly , 2009 .

[29]  Sergiy Minko,et al.  Nanosensors based on responsive polymer brushes and gold nanoparticle enhanced transmission surface plasmon resonance spectroscopy. , 2004, Journal of the American Chemical Society.

[30]  J. Gohy,et al.  A versatile strategy for the synthesis of block copolymers bearing a photocleavable junction , 2010 .

[31]  S. Kubota,et al.  Preparation of positive photoreactive polyimides and their characterization , 1987 .

[32]  M. Urban,et al.  Recent advances and challenges in designing stimuli-responsive polymers , 2010 .

[33]  Hui Zhao,et al.  Highly Ordered Nanoporous Thin Films from Photocleavable Block Copolymers , 2011 .

[34]  S. Kubota,et al.  Synthesis and characterization of positive photosensitive polyimide precursors , 1989 .

[35]  S. C. George,et al.  Novel phototransformation of o-nitrobenzylic polymers to azopolymers , 1994 .

[36]  Yue Zhao,et al.  Fast Photodegradable Block Copolymer Micelles for Burst Release , 2011 .

[37]  B. Sumerlin,et al.  Future perspectives and recent advances in stimuli-responsive materials , 2010 .

[38]  T. Iizawa,et al.  Study of photopolymers. XXXIV. Etherification and esterification reactions of polymers with (o, m, or p)‐bromomethylnitrobenzene using the DBU method and the photochemical properties of the resulting polymers , 1990 .

[39]  Robin D. Rogers,et al.  Aqueous Polymeric Solutions as Environmentally Benign Liquid/Liquid Extraction Media , 1999 .

[40]  Bongjin Moon,et al.  Synthesis of Photocleavable Poly(styrene-block-ethylene oxide) and Its Self-Assembly into Nanoporous Thin Films , 2009 .

[41]  J. Burdick,et al.  Modular synthesis of biodegradable diblock copolymers for designing functional polymersomes. , 2010, Journal of the American Chemical Society.

[42]  M. C. Stuart,et al.  Emerging applications of stimuli-responsive polymer materials. , 2010, Nature materials.

[43]  B. Qi,et al.  Polymer Micelles Stabilization on Demand through Reversible Photo-Cross-Linking , 2007 .

[44]  P. Kamat,et al.  A new photodegradable polyamide containing o-nitrobenzyl chromophore. Steady state and laser flash photolysis studies , 1993 .

[45]  Jongseung Yoon,et al.  Enabling nanotechnology with self assembled block copolymer patterns , 2003 .

[46]  Junsang Doh,et al.  Photogenerated polyelectrolyte bilayers from an aqueous-processible photoresist for multicomponent protein patterning. , 2004, Journal of the American Chemical Society.

[47]  Jean-François Gohy,et al.  Block copolymer micelles , 2005 .

[48]  Luc Tremblay,et al.  Doubly photoresponsive and water‐soluble block copolymers: Synthesis and thermosensitivity , 2010 .

[49]  J. Gohy,et al.  Synthesis of diblock copolymers bearing p-methoxyphenacyl side groups , 2011 .

[50]  C. van Nostrum,et al.  Triggered destabilisation of polymeric micelles and vesicles by changing polymers polarity: an attractive tool for drug delivery. , 2007, Journal of controlled release : official journal of the Controlled Release Society.

[51]  Jean-François Gohy,et al.  Light-responsive block copolymers. , 2010, Macromolecular rapid communications.

[52]  K. Winey,et al.  Reversible stimuli-responsive nanostructures assembled from amphiphilic block copolymers. , 2006, Nano letters.

[53]  Yue Zhao,et al.  How can azobenzene block copolymer vesicles be dissociated and reformed by light? , 2005, The journal of physical chemistry. B.

[54]  Jean-François Gohy,et al.  Photo-induced micellization of block copolymers bearing 4,5-dimethoxy-2-nitrobenzyl side groups , 2011 .

[55]  Tae Hwan Oh,et al.  Synthesis and micropatterning properties of a novel base‐soluble, positive‐working, photosensitive polyimide having an o‐nitrobenzyl ether group , 2007 .

[56]  Yue Zhao,et al.  Toward Photocontrolled Release Using Light-Dissociable Block Copolymer Micelles , 2006 .

[57]  Elsa Reichmanis,et al.  A novel approach to o‐nitrobenzyl photochemistry for resists , 1981 .

[58]  D. Irvine,et al.  Composition-tunable properties of amphiphilic comb copolymers containing protected methacrylic acid groups for multicomponent protein patterning. , 2006, Langmuir : the ACS journal of surfaces and colloids.

[59]  Bin Zhao,et al.  Multiple Micellization and Dissociation Transitions of Thermo- and Light-Sensitive Poly(ethylene oxide)-b-poly(ethoxytri(ethylene glycol) acrylate-co-o-nitrobenzyl acrylate) in Water , 2008 .

[60]  U. Schubert,et al.  Are o-Nitrobenzyl (Meth)acrylate Monomers Polymerizable by Controlled-Radical Polymerization? , 2009 .

[61]  Richard A. Evans,et al.  Photo-responsive systems and biomaterials: photochromic polymers, light-triggered self-assembly, surface modification, fluorescence modulation and beyond , 2010 .

[62]  W. Meier,et al.  Synthesis of Photocleavable Amphiphilic Block Copolymers: Toward the Design of Photosensitive Nanocarriers , 2010 .

[63]  Edward L Cussler,et al.  Cylinder Orientation Mechanism in Block Copolymer Thin Films Upon Solvent Evaporation , 2010 .