Nonlinear Block Copolymers Research Articles

Tuning the morphology of silicon containing copolymers via macromolecular architecture effect

We demonstrate the successful synthesis of linear and non-linear star block copolymers consisting of the highly segregated polystyrene (PS) and poly(dimethylsiloxane) (PDMS) blocks through sequential anionic polymerization combined with chlorosilane chemistry. To study the macromolecular architecture effect on the adopted morphology star block copolymers with six equivalent diblock arms [(PS-b-PDMS)6] were synthesized and compared with their linear diblock copolymer precursors as well as with the corresponding star block copolymers with smaller arm number (2, 3, 4) but identical molecular characteristics. After verifying the molecular and thermal characteristics, bulk studies were carried out through transmission electron microscopy and small angle X-ray scattering. Well-defined structures with enhanced order and similar domain spacing values, irrespective of the architecture complexity of the samples, were observed. The better order of star block copolymers suggests an alternative way to further reduce the lower limit of repeating period by tuning the architecture which is important for the potential future use of the copolymers for nanotechnology related applications. The findings of the specific study are related to the effects of the increased conformational restriction of the inner block. Herein, we show morphological transformations in the (PS-b-PDMS)6 copolymers having non symmetric volume fraction ratios when compared to their linear diblock precursors and triblock copolymers which has not been observed in previous relevant (PS-b-PDMS)n studies that involved stars with less than six arms. To establish the structure/property relationship as a function of arm number, a series of samples involving the diblock precursor, the triblock, the three-, four- and six- arm star block copolymers was prepared, and a systematic comparison was conducted.

Scattering Function and Spinodal Transition of Linear and Nonlinear Block Copolymers Based on a Unified Molecular Model

This work uses a block copolymer architecture [(A′B)nA2]m to unify the scattering function and spinodal transition of typical AB-type block copolymers. The key roles of block number, junction points and asymmetry ratios of block length are (1) to determine the form factor of each block copolymer at the molecular scale; (2) to affect the entropy loss across the spinodal transition and may result in deflection of spinodal curves. The common features are validated in typical linear and nonlinear block copolymers, including AB diblock, asymmetric A′BA triblock, miktoarm stars of ABn, AnBn, (AB)n, (A′B)nA, A′BAm, and multi-graft combs of (BnA2)m and [(A′B)nA2]m. The explicit scattering functions and form factors of various block copolymers can be directly applied in radiation experiments (i.e. neutron or X-ray scattering) to unravel the effect of molecular architecture in solution and microphase separation in disordered melt. The molecular model used in this study is also helpful to guide the chemical synthesis to explore more potentially interesting block copolymers.

Polymer-Ligated Nanocrystals Enabled by Nonlinear Block Copolymer Nanoreactors: Synthesis, Properties, and Applications.

The past several decades have witnessed substantial advances in synthesis and self-assembly of inorganic nanocrystals (NCs) due largely to their size- and shape-dependent properties for use in optics, optoelectronics, catalysis, energy conversion and storage, nanotechnology, and biomedical applications. Among various routes to NCs, the nonlinear block copolymer (BCP) nanoreactor technique has recently emerged as a general yet robust strategy for crafting a rich diversity of NCs of interest with precisely controlled dimensions, compositions, architectures, and surface chemistry. It is notable that nonlinear BCPs are unimolecular micelles, where each block copolymer arm of nonlinear BCP is covalently connected to a central core or polymer backbone. As such, their structures are static and stable, representing a class of functional polymers with complex architecture for directing the synthesis of NCs. In this review, recent progress in synthesizing NCs by capitalizing on two sets of nonlinear BCPs as nanoreactors are discussed. They are star-shaped BCPs for producing 0D spherical nanoparticles, including plain, hollow, and core-shell nanoparticles, and bottlebrush-like BCPs for creating 1D plain and core/shell nanorods (and nanowires) as well as nanotubes. As the surface of these NCs is intimately tethered with the outer blocks of nonlinear BCPs used, they can thus be regarded as polymer-ligated NCs (i.e., hairy NCs). First, the rational design and synthesis of nonlinear BCPs via controlled/living radical polymerizations is introduced. Subsequently, their use as the NC-directing nanoreactors to yield monodisperse nanoparticles and nanorods with judiciously engineered dimensions, compositions, and surface chemistry is examined. Afterward, the intriguing properties of such polymer-ligated NCs, which are found to depend sensitively on their sizes, architectures, and functionalities of surface polymer hairs, are highlighted. Some practical applications of these polymer-ligated NCs for energy conversion and storage and drug delivery are then discussed. Finally, challenges and opportunities in this rapidly evolving field are presented.

Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents.

Block copolymers have attracted significant scientific and economic interest over the last decades due to their ability to self-assemble into ordered structures both in bulk and in selective solvents. In this work, the self-assembly behaviour of both linear (diblocks, triblocks and pentablocks) and nonlinear (miktoarm stars and a block-graft) copolymers based on poly(n-hexyl isocyanate), PHIC, were studied in selective solvents such as n-heptane and n-dodecane. A variety of experimental techniques, namely static and dynamic light scattering, dilute solution viscometry and atomic force microscopy, were employed to study the micellar structural parameters (e.g., aggregation number, overall micellar size and shape, and core and shell dimensions). The effect of the macromolecular architecture, the molecular weight and the copolymer composition on the self-assembly behaviour was studied. Spherical micelles in equilibrium with clusters were obtained from the block copolymers. Thermally stable, uniform and spherical aggregates were found from the triblock copolymers. The poly(n-hexyl isocyanate)-b-polyisoprene-b-poly(n-hexyl isocyanate),-HIH copolymers tend to adopt closed loop conformation, leading to more elongated cylindrical-type structures upon increasing the concentration. Clustering effects were also reported in the case of the pentablock terpolymers. The topology of the blocks plays an important role, since the poly(n-hexyl isocyanate)-b-polystyrene-b-polyisoprene-b-polystyrene-b-poly(n-hexyl isocyanate), HSISH terpolymer shows intermicellar fusion of spherical micelles, leading to the formation of extended networks. The formation of spherical micelles in equilibrium with clusters was obvious in the case of the miktoarm stars, whereas the block-graft copolymer shows the existence of mainly unimolecular micelles.

Polar Organic Solvent-Tolerant Perovskite Nanocrystals Permanently Ligated with Polymer Hairs via Star-like Molecular Bottlebrush Trilobe Nanoreactors.

The key to exploiting perovskite nanocrystals (NCs) for long-term practical use in optoelectronic materials and devices lies in the ability to access stable NCs. Herein, we report the crafting of hairy perovskite NCs with a set of markedly improved stabilities by capitalizing on rationally designed star-like molecular bottlebrush trilobes as nanoreactors. An intriguing star-like molecular bottlebrush trilobe, poly(2-hydroxyethyl methacrylate)-graft-(poly(acrylic acid)-block-partially cross-linked polystyrene (denoted PHEMA-g-(PAA-b-cPS)) is synthesized. Subsequently, it is employed as a polymeric nanoreactor to direct the growth of green-emitting all-inorganic perovskite CsPbBr3 NCs intimately and stably tethered by partially cross-linked PS "hairs" (i.e., cPS-capped CsPbBr3 NCs). The resulting CsPbBr3 NCs exhibit an array of impressive stabilities against UV irradiation, moisture, heat, and water, due to permanently ligated hydrophobic cPS "hairs" on the surface of CsPbBr3 NCs as a result of the original covalent bonding between PAA and cPS blocks. More importantly, cPS-capped CsPbBr3 NCs manifest outstanding stability in various polar organic solvents. Such greatly improved stability can be attributed to the reduced surface defects enabled by the favorable interaction (i.e., coordination interaction and hydrogen bonding) between CsPbBr3 NCs and polar solvents, which dominates over their dissolution by polar solvents. Such exceptional stabilities impart the use of cPS-capped CsPbBr3 NCs as a selective probe for tracing the presence of Cl-/I- in polar organic solvents. The amphiphilic nonlinear block copolymer nanoreactor strategy can afford easy access to stable perovskite NCs of interest with controlled compositions and surface chemistry. They may find applications in solar cells, LEDs, photodetectors, lasers, bioimaging, biosensors, etc.

Miktoarm Amphiphilic Block Copolymer with Singlet Oxygen-Labile Stereospecific β-Aminoacrylate Junction: Synthesis, Self-Assembly, and Photodynamically Triggered Drug Release.

Incorporation of a desired stimuli-responsive unit in a stereospecific manner at the specific location within a nonlinear block copolymer architecture is a challenging task in synthetic polymer chemistry. Herein, we report a facile and versatile method to synthesize AB2 miktoarm block copolymers bearing a singlet oxygen (1O2)-labile regio and stereospecific β-aminoacrylate linkage with 100% E-configuration at the junction via a combination of amino-yne click chemistry and ring opening polymerization. Using this strategy, a series of 1O2-responsive AB2 amphiphilic miktoarm (MA)copolymers composed of hydrophilic polyethylene glycol (PEG) as the A constituent and hydrophobic polycaprolactone (PCL) as the B constituent (MA-PEG- b-PCL2) was synthesized by varying the block length of PCL. The self-assembly characteristics of these well-defined MA-PEG- b-PCL2 copolymers in an aqueous condition were studied by solvent displacement and thin-film hydration method, and their morphologies were investigated using transmission electron microscopy. The copolymers formed spherical, cylindrical, or lamella morphologies, depending on the chain length and preparation conditions. A hydrophobic photosensitizer chlorin e6 (Ce6) and anticancer drug doxorubicin (DOX) were efficiently encapsulated into the hydrophobic core of MA-PEG- b-PCL2 copolymer micelles. These coloaded micelles were taken up by human breast cancer (MDA-MB-231) cells. Upon red laser light irradiation, the 1O2-generated by the Ce6 induced photocleavage of the β-aminoacrylate moiety, leading to the dissociation of the micellar structure and triggered intracellular drug release for effective therapy. Overall, rapid disassembly upon 1O2 generation and subsequent controlled intracellular drug release suggested that these micelles bearing β-aminoacrylate linkage have a huge potential for on-demand drug delivery.

Effect of polymers on worm-like micelles of cetyltrimethylammonium tosylate

Abstract Aqueous solution behaviour of worm-like micelles of cetyltrimethylammonium tosylate (CTAT) was examined in the presence of some water soluble nonionic polymers viz. poly(ethylene oxide) 4000 (PEO 4K), poly(propylene oxide) 1000 (PPO 1K), poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) and poly(propylene oxide)-poly(ethylene oxide)-poly(propylene oxide) (PPO-PEO-PPO) type linear triblock copolymers and nonlinear octablock copolymers by an array of techniques. CTAT forms worm-like micelles at very low concentrations. Very hydrophilic PEO 4K molecules surround micelle surface leading to viscosity increase while PPO 1K and linear triblock copolymers demonstrates distinct interaction with worm-like CTAT micelles. They form smaller mixed micelles strongly depending on their structure and hydrophobicity. Structurally different PEO-PPO-PEO type nonlinear block copolymer display dissimilar effect on morphology of CTAT micelles. Small angle neutron scattering (SANS) measurements provide clear idea about structural transitions from worm-like to spherical/ellipsoidal micelles with different dimensions. The different behaviour shown by the polymers is explained on the basis of their interaction with different interiors of CTAT micelles. 1 H NMR and nuclear overhauser enhancement spectroscopy (NOESY) experiments provide idea about location of these additives and site of interaction. The present study validates how the size of worm-like micelles can easily be tuned up by different polymers.

Supramolecular self-assembly of novel thermo-responsive double-hydrophilic and hydrophobic Y-shaped [MPEO-b-PEtOx-b-(PCL)2] terpolymers

Nonlinear amphiphilic block copolymer architectures with precisely controlled structures bring new challenges to biomedical materials research.

Synthesis, characterization, crystalline morphologies and hydrophilicity of A4 BA4 nonlinear block copolymers

Novel, well-defined A4BA4 nonlinear block copolymers [poly(ϵ-caprolactone)]4-block-poly(propylene oxide)-block-[poly(ϵ-caprolactone)]4 (PCL4-b-PPO-b-PCL4) with eight arms were synthesized by ring-opening polymerization. An investigation of melting and crystallization demonstrated that the values of crystallization temperature, melting temperature and degree of crystallinity of PCL4-b-PPO-b-PCL4 were enhanced with an increase of PCL chain length. At the same time, the crystallizability of PCL segments was influenced by the star-shaped structure of the copolymers and the amorphous PPO segments in the copolymers. Furthermore, PCL4-b-PPO-b-PCL4 showed crystalline morphologies that were different from that of linear PCL according to polarized optical microscopy. Moreover, the hydrophilicity of the copolymers could be improved and adjusted by the star-shaped structure and the alteration of the relative content of the PCL and PPO segments in the copolymers.© 2013 Society of Chemical Industry

Cooperative self-assembly and crystallization into fractal patterns by PNIPAM-based nonlinear multihydrophilic block copolymers under alkaline conditions

Hierarchical two-dimensional patterned nanomaterials fabricated by bottom-up self-assembly are of great interests in practical applications. A series of nonlinear multihydrophilic block copolymers (MHBCs), consisting of poly(N-isopropylacrylamide) (PNIPAM), poly(acrylic acid) (PAA) and/or poly(vinyl pyrrolidone) (PVP) segments, were employed to fabricate well-defined fractal patterns under alkaline conditions by a simple solvent evaporation process. The formation of fractal patterns was discovered to obey a diffusion-limited aggregation process by needle-shaped intermediate nanostructures, which are actually nanohybrids formed by the cooperative self-assembly and crystallization of polymers and alkalis. The ability of MHBCs to form fractal patterns is closely related to their structural architectures, and is also significantly influenced by temperature, alkaline concentration, alkali type and substrate. Upon evaporation, PAA segments serve as the growing scaffolds of alkali crystallization along with the occurrence of self-contraction and intermolecular association of PNIPAM segments. PVP segments are not necessary for fractal patterning, which, however, can prompt the self-assembly into more perfect dendritic patterns in the case of a proper structural linking sequence. The observations reported here can provide a better understanding of molecular self-assembly toward complex patterns at multiple length scales, which may gain potential applications in advanced devices, sensors and microprinting.

Effect of structural constraint on dynamic self-assembly behavior of PNIPAM-based nonlinear multihydrophilic block copolymers

The effects of structural constraint on the thermosensitivity and dynamic self-assembly behaviors of PNIPAM-based nonlinear multihydrophilic block copolymers (MHBCs) are investigated by a combination of calorimetric, NMR, FTIR, DLS and zeta potential measurements. Two novel miktoarm star MHBCs, (PNIPAM)2-(PVP-b-PAA)2 with PNIPAM segments constrained at one end and (PNIPAM-b-PAA)2-(PVP)2 with PNIPAM segments constrained at two ends, are mainly analyzed to make comparison. As we previously reported (Soft Matter, 2012, 8, 3980), in (PNIPAM)2-(PVP-b-PAA)2 the three polymeric segments have relatively independent phase behaviors during the formation of PNIPAM-core micelles. However, by introducing more structural constraints to PNIPAM segments, (PNIPAM-b-PAA)2-(PVP)2 exhibits a much smoother and weaker phase transition. Additional analysis by IR spectroscopy, in combination with perturbation correlation moving window (PCMW) and two-dimensional correlation spectroscopy (2DCOS), indicates that PVP segments in (PNIPAM-b-PAA)2-(PVP)2 show phase transition-like behavior by participating in the self-association process of PNIPAM segments, and there are both unimers and small associates existing in the solution below the LCST due to the slight interaction between PVP and PNIPAM segments. Moreover, due to the presence of PVP segments in the core, the micelles formed by (PNIPAM-b-PAA)2-(PVP)2 should have a loosely organized superstructure, which may account for the weak phase transition and low degree of phase separation. Finally, we propose a mechanism of the self-assembly process of (PNIPAM-b-PAA)2-(PVP)2, which is further confirmed by DLS and zeta potential measurements.

Dynamic self-aggregation behavior of a PNIPAM-based nonlinear multihydrophilic block copolymer revealed by two-dimensional correlation spectroscopy

IR spectroscopy in combination with the perturbation correlation moving window (PCMW) technique and 2D correlation spectroscopy (2DCOS) is employed to elucidate the dynamic self-aggregation behavior of a novel miktoarm star PNIPAM-based multihydrophilic block copolymer, poly(N-isopropylacrylamide)2–[poly(N-vinylpyrrolidone)-b-poly(acrylic acid)]2 ((PNIPAM)2–(PVP-b-PAA)2). At pH = 8, (PNIPAM)2–(PVP-b-PAA)2 tends to self-assemble into micelles with PNIPAM in the core and ionized PAA segments in the shell during heating. IR investigation shows that the AA segments exhibit a similar “phase transition” behavior to the PNIPAM segments, which can be ascribed to the indirect influence through the drastic content changes of water molecules along with the hydrophilic-to-hydrophobic transformation of PNIPAM segments. Boltzmann fitting and PCMW easily determine the transition temperature to be ca. 33 °C and the transition temperature range to be 29.5–35 °C. Moreover, 2DCOS discerns a sequential group motion from PNIPAM to PVP and PAA segments. It is concluded that the three polymeric segments have relatively independent phase behavior during the formation of PNIPAM-core micelles, and the chain conformation adjustment induced by hydrophilic-to-hydrophobic transformation of PNIPAM segments should be the driving force of the whole self-aggregation process. The dynamic self-aggregation process we proposed can be further confirmed by dynamic laser scattering (DLS) and zeta potential measurements.

GPC-低角度光散乱測定法による非線状ブロック共重合体の絶対分子特性化

低角度光散乱光度計付きGPC (GPC-LALLS)を用いて，新たに導出した解析式により非線状ブロック共重合体の絶対分子特性化を行った．ブロック共重合体の二つの組成分布を考慮してこの解析式を求めた．一つ目は異なった分子量におけるそれであり，二つ目は同じ分子量内でのそれである．スチレン基を片末端にもつポリスチレンマクロモノマーとポリイソプレンマクロモノマーを逐次リビングアニオン重合して(PSt)n-star-(PIs)mヘテロアーム星型共重合体を合成した．PSt-graft-ポリ(n-ヘキシルイソシアナート)グラフト共重合体を逐次分解して，グラフト鎖数が異なるグラフト共重合体を合成した．これら非線状ブロック共重合体の絶対分子量をGPC-LALLSにより決定し，組成分布をRIとUV検出器の併用により決定した．(PSt)n-star-(PIs)mの三次元分子量分布や腕鎖数分布も決定した．

Thermodynamic of micelle formation of nonlinear block co-polymer Tetronic ® T904 in aqueous salt solution

Calorimetric and spectroscopic studies have been carried out to investigate the thermodynamics of temperature-induced micellization of Tetronic ® T904 [(EO 15PO 17) 2NCH 2CH 2N (PO 17EO 15) 2] in aqueous salt solutions. High-sensitivity differential scanning calorimetry (HSDSC), nuclear magnetic resonance (NMR) and Fourier transfer infrared (FTIR) measurements were used to evaluate the critical micellization temperature (CMT). The critical micellization concentration (CMC) and the thermodynamic parameters of micelle formations, namely enthalpy (Δ H mic), Gibbs energy (Δ G mic), and entropy (Δ S mic) of micellization were determined as a function of temperature and salt concentration using isothermal calorimetry (ITC). These measurements indicated spontaneous micellization with substantial enthalpy–entropy compensation of T904 micellization.

Induced micellization and micellar transitions in aqueous solutions of non-linear block copolymer Tetronic® T904

Tetronics® (Poloxamines) are the least studied block copolymers with an X-shaped molecular geometry formed by four poly (propylene oxide, PPO) and poly (ethylene oxide, PEO) block chains, bonded to a central ethylenediamine group. Compared to their linear counterparts, the Pluronics, Tetronics® are novel, in that they possess superior physicochemical properties, and are relatively less studied. A complete understanding of their solution behavior under different solution conditions can make them competitive candidates for novel drug delivery systems. The micellization behavior and aqueous solution properties of Tetronic® T904 [(EO(15)PO(17)) (2)NCH(2)CH(2)N (PO(17)EO(15))(2)] have been determined by cloud point, viscosity, dynamic light scattering (DLS), small-angle neutron scattering (SANS), and nuclear magnetic resonance (NMR) measurements. The copolymer formed spherical micelles at 30°C with a core radius (R(c)) of about 2.5 nm, a hard sphere radius (R(hs)) of 5.2 nm and an aggregation number (N(agg)) of 10. The effect of copolymer concentration, temperature, pH and salt on the micellar and phase behavior is examined. The copolymer has been found to exist in aggregated form only at higher pH values of >8. An increase in micelle size and aggregation has been observed for an increase in temperature and salt concentration, mainly due to the dehydration of the hydrated PEO shell. The added salts (NaCl, Na(2)SO(4) and Na(3)PO(4)) induce micellization and favor the micellar transition at lower temperatures due to the "salting out effect"; the effect of anions follows the Hofmeister series (PO(4)(3-)>SO(4)(2-)>Cl(-)).

Design of Soft and Strong Thermoplastic Elastomers Based on Nonlinear Block Copolymer Architectures Using Self-Consistent-Field Theory

Thermoplastic elastomers (TPEs) that are soft at low extension yet strong at large extension are of great importance in a variety of technological applications. In ABA-triblock architectures, both the overall molecular weight and the composition of the glassy A-blocks correlate with TPE strength. The design space of current TPEs based on linear ABA triblock copolymers (e.g., polystyrene-b-polybutadiene-b-polystyrene) is restricted by the accessibility of the order−disorder transition temperature, limiting the molecular weight, and restricted by the maximum volume fraction for which glassy A-blocks will form discrete domains. Using self-consistent-field theory (SCFT), we designed in silico two new, nonlinear TPE architectures that significantly relax the composition restriction: radial (ABA′)n and A(BA′)n miktoarm star-block copolymers with chemically identical, but unequal, molecular weight A-blocks. Through a balance of end-block bidispersity, block extraction from the interface, and architectural asymmetry, these molecular architectures are able to stabilize phases with discrete A-rich domains at remarkably high overall A-monomer compositions (fA). In some cases the maximum fA achieved for phases with discrete A-rich domains surpasses twice that of conventional linear ABA TPEs.

Supramolecular Self‐Assembly of Nonlinear Amphiphilic and Double Hydrophilic Block Copolymers in Aqueous Solutions

Supramolecular self-assembly of block copolymers in aqueous solution has received ever-increasing interest over the past few decades due to diverse biological and technological applications in drug delivery, imaging, sensing and catalysis. In addition to relative block lengths, molecular weights and solution conditions, chain architectures of block copolymers can also dramatically affect their self-assembling properties in selective solvents. This feature article mainly focuses on recent developments in the field of supramolecular self-assembly of amphiphilic and double hydrophilic block copolymers (DHBCs) possessing nonlinear chain topologies, including miktoarm star polymers, dendritic-linear block copolymers, cyclic block copolymers and comb-shaped copolymer brushes.

Synthesis and Micellization Properties of Double Hydrophilic A2BA2and A4BA4Non-Linear Block Copolymers

We describe the first account of the synthesis and intriguing micellization properties of nonlinear double hydrophilic block copolymers (DHBCs) of the A2BA2 and A4BA4 type. Atom transfer radical polymerization (ATRP) macroinitiators with two and four initiating sites at both ends of poly(propylene oxide) (PPO) chain were synthesized via reacting 2-hydroxyethyl acrylate and glycidol with commercially available diamine-terminated PPO, respectively, followed by esterification with excess 2-bromoisobutyryl bromide or 2-bromopropionyl bromide. Well-defined nonlinear DHBCs, (PDEA)2PPO(PDEA)2 (H-shaped) and (PDEA)4PPO(PDEA)4 (star-b-linear-b-star), were then prepared by polymerizing 2-(diethylamino)ethyl methacrylate (DEA) via ATRP in 2-propanol at 40 °C using the prepared macroinitiators, where PDEA was poly(2-(diethylamino)ethyl methacrylate). The structures of the resulting nonlinear shaped copolymers were characterized by 1H NMR and gel permeation chromatography (GPC). The pH- and thermoresponsive micellization behavior of (PDEA10)2PPO(PDEA10)2 and (PDEA11)4PPO(PDEA11)4 was then investigated by a combination of dynamic laser light scattering (LLS) and fluorescence techniques. Compared to the linear counterpart, the nonlinear block copolymers exhibited complex and interesting micellization properties.

Block copolymers: synthetic strategies, physical properties, and applications

Preface. Abbreviations and Symbols. I: BLOCK COPOLYMER SYNTHESIS. 1 Block Copolymers by Anionic Polymerization. 2 Block Copolymers by Cationic Polymerization. 3 Block Copolymers by Living Free Radical Polymerization. 4 Block Copolymers by Group Transfer Polymerization. 5 Block Copolymers by Ring Opening Metathesis Polymerization. 6 Synthesis of Block Copolymers by a Combination of Different Polymerization Methods. 7 Synthesis of Block Copolymers by Chemical Modification. 8 Nonlinear Block Copolymers. II: MOLECULAR CHARACTERIZATION OF BLOCK COPOLYMERS. 9 Molecular Characterization of Block Copolymers. III: SOLUTION PROPERTIES OF BLOCK COPOLYMERS. 10 Dilute Solutions of Block Copolymers in Nonselective Solvents. 11 Dilute Solutions of Block Copolymers in Selective Solvents. 12 Adsorption of Block Copolymers At Solid-Liquid Interfaces. IV: PHYSICAL PROPERTIES OF BLOCK COPOLYMERS. 13 Theory. 14 Structure Factor and Chain Architecture. 15 Block Copolymer Phase State. 16 Viscoelastic Properties of Block Copolymers. 17 Phase Transformation Kinetics. 18 Block Copolymers with Strongly Interacting Groups. 19 Block Copolymer Morphology. 20 Block Copolymer Dynamics. V: APPLICATIONS. 21 Block Copolymer Applications. Index.

Synthesis of Model PS(PI)5 and (PI)5PS(PI)5 Nonlinear Block Copolymers of Styrene (S) and Isoprene (I)

Synthesis of Model PS(PI)₅ and (PI)₅PS(PI)₅ Nonlinear Block Copolymers of Styrene (S) and Isoprene (I)