Functionalization of shaped polymeric nanoobjects via bulk co-self-assembling gelable block copolymers with silane coupling agents

Hairy polymer nanoobjects (PNOs) of different shapes can be easily obtained by cross-linking the discontinuous microphases of bulk block copolymers followed by dispersing in a solvent. Herein we report a general approach to functionalize the shaped PNOs by bulk microphase separation of poly(3-(triethoxysilyl)propyl methacrylate)-block-polystyrene (PTEPM-b-PS) copolymers in the presence of functional silane coupling agents. The silanes like (3-mercaptopropyl)trimethoxysilane and (3-chloropropyl)trimethoxysilane were enriched into the PTEPM discontinuous microdomains selectively. The microphase structures were characterized by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) of microtomed slices. For the PTEPM₇₈-b-PS₃₄₈ which had a lamellar structure, its blending mixtures with MMS and CMS whose content reached up to 50 wt% still remained as a lamellar structure. When small amount of MMS or CMS was added, the PTEPM₇₁-b-PS₇₈₀ as hexagonally packed cylinders remained its structure. However, the morphology changed into lamellae at higher content of the silanes. For PTEPM₄₆-b-PS₁₆₆₉, its spherical structure remained but the size distribution became broad gradually with increase of silanes. By inducing gelation and then dispersing in a good solvent of PS phases, hairy PNOs having lamellar, cylindrical or spherical shape with their cores being functionalized with the groups from co-gelated silanes were obtained.     

Thermoresponsive core-shell-corona micelles of poly(ethyleneglycol)-b-poly(N-isopropylacrylamide)-b-polystyrene

Core-shell-corona micelles with a thermoresponsive shell self-assembled by triblock copolymer of poly(ethyleneglycol)-b-poly(N-isopropylacrylamide)-b-polystyrene (PEG₄₅-b-PNIPAM₁₆₈-b-PS₄₆) are studied by ¹H NMR, light scattering and atomic force microscopy. The thermoresponsive triblock copolymer, which has a relatively short hydrophobic PS block, can disperse in water at room temperature to form core-shell-corona micelles with the hydrophobic PS block as core, the thermoresponsive PNIPAM block as shell and the hydrophilic PEG block as corona. At temperature above lower critical solution temperature (LCST) of the PNIPAM block, the PNIPAM chains gradually collapse on the PS core to shrink the size and change the structure of the resultant core-shell-corona micelles with temperature increasing. It is found that there possibly exists an interface between the PNIPAM shell and PEG corona of the core-shell-corona micelles at temperature above LCST of the PNIPAM block.     

Microstructure and performance of block copolymer modified epoxy coatings

The effects of two diblock copolymers, poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP–PEO) and poly(1,2-butadiene)-b-poly(2-vinyl pyridine) (PB–P2VP) on the mechanical properties of epoxy coatings were studied. Both modifiers self-assembled into spherical micelles of 10–20 nm diameter in cured bulk epoxy. This morphology was preserved in 15 μm thick coatings; however, micelle segregation to the coating/substrate interface was also observed. The critical strain energy release rate, G_1c, of bulk thermosets was enhanced by up to fivefold with the addition of block copolymers. Likewise, the abrasive wear resistance of thin coatings increased with modifier inclusion. The results showed that at 5 wt.% of loading, block copolymers were able to impart a 40% increase in abrasive wear resistance to modified coatings over neat ones. Block copolymer modifiers did not sacrifice the modulus and glass transition temperature of bulk thermosets and coatings, or the hardness and transparency of coatings.     

Amphiphilic block copolymers bearing strong push-pull azo chromophores: Synthesis, micelle formation and photoinduced shape deformation

In this work, a series of amphiphilic diblock copolymers bearing strong push-pull type azo chromophores was synthesized through post-polymerization azo-coupling reaction scheme. The copolymers (P(CNAZO_m-b-MAA_n)), composed of 2-(N-ethyl-N-(4-(4′-cyanophenylazo)-phenyl)amino)ethyl methacrylate (CNAZO) and methacrylic acid (MAA) blocks, were obtained through four-step reactions. Firstly, precursor diblock copolymers (P(EMA_m-b-tBMA_n)) were obtained through sequential two-stage ATRP reactions of 2-(N-ethyl-N-phenylamino)ethyl methacrylate (EMA) and tert-butyl methacrylate (tBMA). Then, 4-amino-4′-cyanoazobenzene chromophores were introduced by azo-coupling reaction of P(EMA_m-b-tBMA_n) with diazonium salt of 4-aminobenzonitrile. Finally, P(CNAZO_m-b-MAA_n) was obtained through selective hydrolysis of the tert-butyl ester linkages in the tBMA blocks. Three block copolymers with the same CNAZO block length (m = 100) and different MAA block lengths (n = 5, 13, 23) were prepared by this method. The polymer and copolymers prepared in the process were characterized by GPC, ¹H NMR, UV-vis, DSC and TGA measurements. Results show that P(CNAZO_m-b-MAA_n) forms spherical micellar aggregates by gradually increasing the water content in THF/H₂O mixtures. The diameters of the spherical aggregates are related to the composition of the block copolymers and the water-adding rate. The block copolymer with larger molecular weight of the hydrophilic MAA block forms the aggregates with the smaller average size. The increase of the water-adding rate also shows an effect to reduce the diameters. Upon irradiation with a linearly polarized Ar⁺ laser beam, the spherical aggregates can be elongated in the light polarization direction. The deformation degree shows an almost linear dependence on the light irradiation time in the testing period. The deformed aggregates can recover the original spherical shape after thermal annealing at a temperature above T_g of the block copolymer.     

Dilute solutions and phase behavior of polydisperse A-b-(A-co-B) diblock copolymers

The effect of polydispersity on dilute solution properties and microphase separation of polydisperse high-molecular-weight (M_w > 10⁵ g mol⁻¹) polystyrene-block-poly(styrene-co-acrylonitrile) diblock copolymers, PS-block-P(S-co-AN), was studied in this work. For experiments, a series of diblock copolymers with variable weight fractions of acrylonitrile units (w_AN = 0.08-0.29) and length of block P(S-co-AN) was synthesized using nitroxide-mediated radical polymerization (NMP) technique, namely, by chain extension of nitroxide-terminated polystyrene (PS-TEMPO). According to light scattering and viscometry measurements in dilute tetrahydrofuran (THF) solutions the studied diblock copolymers assumed random coil conformation with the values of characteristic structure factor R_g/R_h = 1.50-1.76. It was found that polydisperse diblock copolymers being in strong segregation limit (SSL) self-assembled into microphase-separated ordered morphologies at ordinary temperature. The long periods of lamellar microdomains were larger compared to theoretical predictions for hypothetical monodisperse diblock copolymers. It was demonstrated by means of SAXS and TEM that a transition from a lamellar (LAM) to irregular face-centered-cubic (FCC) morphology occurred with increasing volume fraction of P(S-co-AN) block.     

Synthesis of amphiphilic triblock copolymers and application for morphology control of calcium carbonate crystals

A series of amphiphilic triblock copolymers poly(ethylene glycol)-block-poly(acrylic acid)-block-poly(n-butyl acrylate) (PEG-b-PAA-b-PnBA) differing only in the relative block lengths were synthesized by the acid-catalyzed elimination of the tert-butyl groups from poly(ethylene glycol)-block-poly(tert-butyl acrylate)-block-poly(n-butyl acrylate) (PEG-b-PtBA-b-PnBA), which was synthesized by atom-transfer radical polymerization (ATRP). The degree of polymerization, molecular weight and percentage of hydrolysis of the product PEG-b-PAA-b-PnBA were studied by gel permeation chromatography (GPC), NMR and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS). Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to study the aggregation states of copolymers in water solution. The radii of the copolymer micelles shrink as Ca²⁺ is introduced into the solutions. The crystallization behaviors of calcium carbonate controlled by copolymer 1 (PEG₁₁₂-b-PAA₈₆-b-PnBA₆₀) and copolymer 2 (PEG₁₁₂-b-PAA₄₀-b-PnBA₇₂) differing mainly in the length of PAA block were systematically studied. It was found that the crystallization products are composed of calcite and vaterite, and the ratio of vaterite to calcite increases with increasing the concentration of copolymer 1. For copolymer 2, however, only calcite is obtained at all the concentration range investigated in this work.     

Formation of nanostructures in thermosets containing block copolymers: From self-assembly to reaction-induced microphase separation mechanism

In this work, we investigated the effect of formation mechanisms of nanophases on the morphologies and thermomechanical properties of the nanostructured thermosets containing block copolymers. Toward this end, the nanostructured thermosets involving epoxy and block copolymers were prepared via self-assembly and reaction-induced microphase separation approaches, respectively. Two structurally similar triblock copolymers, poly(ε-caprolactone)-block-poly(butadiene-co-styrene)-block-poly(ε-caprolactone) (PCL-b-PBS-b-PCL) and poly(ε-caprolactone)-block-poly(ethylene-co-ethylethylene-co-styrene)-block-poly(ε-caprolactone) (PCL-b-PEEES-b-PCL) were synthesized via the ring-opening polymerization of ε-caprolactone (CL) with α,ω-dihydroxyl-terminated poly(butadiene-co-styrene) (HO-PBS-OH) and α,ω-dihydroxyl-terminated poly(ethylene-co-ethylethylene-co-styrene) (i.e., HO-PEEES-OH) as the macromolecular initiators, respectively; the latter was obtained via the hydrogenation reduction of the former. Both the triblock copolymers had the same architecture, the identical composition and close molecular weights. In spite of the structural resemblance of both the triblock copolymers, the formation mechanisms of the nanophases in the thermosets were quite different. It was found that the formation of nanophases in the thermosets containing PCL-b-PBS-b-PCL followed a reaction-induced microphase separation mechanism whereas that in the thermosets containing PCL-b-PEEES-b-PCL was in a self-assembly manner. The different formation mechanisms of nanophases resulted in the quite different morphologies, glass transition temperatures (T_g's) and fracture toughness of the nanostructured thermosets.     

Surface characterization of segmented siloxane–urethane block copolymers

New siloxane–urethane block copolymers were synthesized and the effect of a siloxane moiety on microphase segregation in soft/hard block copolymers was studied by several analytical methods. Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) provided topographical and bulk composition information. Electron Spectroscopy for Chemical Analysis (ESCA) provided surface chemical information. Fourier Transform Infrared Spectroscopy (FTIR) provided chemical bond information for the near-surface region. Thermogravimetric Analysis (TGA) provided information concerning the thermal stability of the polymers. Differential Scanning Calorimetry (DSC) provided information on the soft and hard block segments within the polymer. These studies showed that the block copolymer contained and enhanced silicone-containing surface. For films cast on glass, less silicon was detected in the bulk (exposed by physically removing the surface material), and on the backside (glass) of the polymer film, than on the air-exposed surface. Of particular interest is the fact that data also show that the solvents, from which the polymers were cast, have a significant influence on microphase segregation. The films cast from THF have higher silicone concentrations at the surface as compared to polymers cast from DMAC/CH₂CL₂ or dioxane. © 1993 John Wiley & Sons, Inc.     

Photoresponsive diblock copolymers bearing strong push–pull azo chromophores and cholesteryl groups

A series of diblock copolymers bearing strong push–pull azo chromophores and cholesteryl groups on the respective blocks was synthesized by reversible addition fragmentation chain transfer (RAFT) polymerization. The liquid crystal phase structure, microphase-separated morphology, and photoresponsive properties of the block copolymers were investigated by using DSC, POM, AFM, XRD and laser irradiation. The results show that the cholesteryl block (PChEMA) forms smectic-A mesophase and the morphology depends on the length of the azo block (PAzoCN). When the azo block is short, such as PChEMA₅₀-b-PAzoCN₇, no microphase separation can be identified. For PChEMA₅₀-b-PAzoCN₂₈, PAzoCN appears as the hexagonal-packed nanocylinders embedded in the PChEMA matrix. When the azo block length further increases, the block copolymer PChEMA₅₀-b-PAzoCN₇₃ forms microphase-separated lamellae. The microphase separation shows no obvious restraint on the photoinduced orientation of the azo chromophores, but micron-scale mass transport of the photoresponsive PAzoCN block is inhibited by the phase confinement.     

Precise preparation of four-arm-poly(ethylene glycol)-block-poly(trimethylene carbonate) star block copolymers via activated monomer mechanism and examination of their solution properties

The polymerization of trimethylene carbonate (TMC) in the presence of HCl·Et₂O via activated monomer mechanism was performed to synthesize 4a-PEG-b-PTMC star block copolymers composed of poly(ethylene glycol) (PEG) and poly(trimethylene carbonate) (PTMC) using four-arm (4a) PEG as an initiator. The TMC conversion and molecular weight of PTMC increased linearly with the polymerization time or the feed ratios of the TMC to 4a-PEG in the presence of HCl·Et₂O in CH₂Cl₂ at 25 °C. The obtained PTMC had molecular weights close to the theoretical value calculated from TMC to PEG molar ratio and exhibited monomodal GPC curve. We prepared successfully 4a-PEG-b-PTMC star block copolymers without metal catalyst at room temperature via living ring-opening polymerization (ROP) of TMC from 4a-PEG as an initiator in the presence of HCl·Et₂O as a monomer activator. The CMCs of the 4a-PEG-b-PTMC star block copolymers determined from fluorescence measurements. The CMCs of the 4a-PEG-b-PTMC star block copolymers decreased in the order of the increase in the PTMC segment. The partition equilibrium constant, K_v, which is an indicator of the hydrophobicity of the micelles of the 4a-PEG-b-PTMC star block copolymers in aqueous media, increased with the increase in the PTMC segment. In conclusion, we confirmed that the 4a-PEG-b-PTMC star block copolymers form micelles and hence may be potential hydrophobic-drug delivery vehicles.     

Phase behavior and structure formation for diblock copolymers composed of side-chain liquid crystalline and glassy amorphous components

Phase behavior and structure formation in liquid crystallization of a side-chain liquid crystalline (LC) block copolymers composed of poly[11-(4′-cyanophenyl-4″-phenoxy)undecyl acrylate] (PA₁₁OCB) and polystyrene (PSt) were investigated by using a time-resolved small-angle X-ray scattering technique (SAXS), differential scanning calorimetry and polarizing optical microscopy. PA₁₁OCB homopolymer formed smectic (Sm) liquid crystal. Liquid crystallization behavior of the block copolymers depended on the molecular weight and the block composition. When molecular weight was relatively low, order-disorder transition (ODT) was observed. In cooling of such block copolymers, liquid crystallization seemed to wait for the formation of LC-rich microphase by ODT. For the block copolymers with relatively high molecular weight, liquid crystallization slightly enlarged the domain spacing without changing the microphase separation structure in the melt. The order of the LC phase was lowered with decreasing dimensionality of the LC microdomains, that is, the LC blocks formed smectic liquid crystal in the matrix or lamellar microphase while liquid crystallization in the cylindrical microdomains did not show smectic but maybe nematic liquid crystal. Moreover, the LC blocks within the spherical microdomains did not liquid crystallize. From the 2-D SAXS with applying shear flow, the Sm layers were orientated perpendicularly to the interface of the microphase separation. The relation between the layer thickness of the LC phase and the molecular weight suggested that the main chain was extended normally to the interface of the microphase separation.     

Synthesis and self-assembly behaviors of three-armed amphiphilic block copolymers via RAFT polymerization

The novel trifunctional reversible addition-fragmentation chain transfer (RAFT) agent, tris(1-phenylethyl) 1,3,5-triazine-2,4,6-triyl trithiocarbonate (TTA), was synthesized and used to prepare the three-armed polystyrene (PS₃) via RAFT polymerization of styrene (St) in bulk with thermal initiation. The polymerization kinetic plot was first order and the molecular weights of polymers increased with the monomer conversions with narrow molecular weight distributions (M_w/M_n ≤ 1.23). The number of arms of the star PS was analyzed by gel permeation chromatography (GPC), ultraviolet visible (UV-vis) and fluorescence spectra. Furthermore, poly(styrene-b-N-isopropylacrylamide)₃ (PS-b-PNIPAAM)₃, the three-armed amphiphilic thermosensitive block copolymer, with controlled molecular weight and well-defined structure was also successfully prepared via RAFT chain extension method using the three-armed PS obtained as the macro-RAFT agent and N-isopropylacrylamide as the second monomer. The copolymers obtained were characterized by GPC and ¹H nuclear magnetic resonance (NMR) spectra. The self-assembly behaviors of the three-armed amphiphilic block copolymers (PS-b-PNIPAAM)₃ in mixed solution (DMF/CH₃OH) were also investigated by high performance particle sizer (HPPS) and transmission electron microscopy (TEM). Interestingly, the lower critical solution temperature (LCST) of aqueous solutions of the three-armed amphiphilic block copolymers (PS-b-PNIPAAM)₃ decreased with the increase of relative length of PS in the block copolymers.     

Microphase behaviour of ferrocenyldimethylsilane-b-methylmethacrylate diblock copolymers

A series of narrowly distributed diblock copolymers from poly(1,1′-ferrocenyldimethylsilane) (PFS) and polymethylmethacrylate (PMMA) was prepared via anionic polymerisation and characterised with respect to their thermal and morphological behaviour in the bulk. TGA and DSC experiments reveal a high thermal stability of the block copolymers up to temperatures of above 220 °C. Homogeneous films (ca. 1 mm in thickness) were prepared from these materials by standard film-casting procedures followed by annealing at elevated temperatures. These films were characterised by transmission electron microscopy (TEM). Depending on the PFS volume fraction, ?_PFS (0.25≤?_PFS≤0.48), the three classical microphase morphologies were found, i.e. the spherical, hexagonal and lamellar ones. Due to the strong segregation tendency of PFS and PMMA, no complex morphologies such as the gyroidic were found for the rather high-molecular-weight samples under investigation here. Instead, either the direct transition from the hexagonal into the lamellar morphology was observed when the PFS content crosses the critical value of ?_PFS=0.40, or the coexistence of these two morphologies was found.     

Influence of block composition on structural,thermal and mechanical properties of novel aliphatic polyester based triblock copolymers

A series of ABA type triblock copolymers [Poly(lactide)-block-poly(hexamethylene 2,3-O-isopropylidene tartarate)-block-poly(lactide)] PLA-b-PHIT-b-PLA based on renewable monomers l-tartaric acid and l-lactide have been synthesized and the effect of the PLA chain length on the properties of the triblock copolymers has been systematically investigated. The block nature of the copolymers was established by differential scanning calorimetry (DSC) which showed two glass transition temperatures (T_g) corresponding to PHIT and PLA blocks. Solution cast films of these triblock copolymers turned out to be brittle in nature and to overcome this, ε-caprolactone was copolymerized with l-lactide to generate a separate series of triblock copolymers [PLA-ran-PCL]-b-PHIT-b-[PLA-ran-PCL]. Our study systematically demonstrates that the PLA-to-PCL ratio in the outer block composition influences the mechanical properties via a delayed post-yield stress drop phenomenon. The study further elaborates the time-synchronized strain-field analysis of the novel triblocks to be a convincing approach for the characterization of micro-deformation modes.     

Chaperone-like α-cyclodextrins assisted self-assembly of double hydrophilic block copolymers in aqueous medium

Chaperones are defined as a family of protein that mediates the correct assembly of other polypeptides but that are not components of the functional assembled structures. In this work, we have devised a novel method in which α-cyclodextrins (α-CDs), “artificial chaperones”, facilitate block copolymers self-assembling into the expected structure. Poly(ethylene oxide)-b-poly(4-vinylpyridine) (PEO₄₅-b-P4VP₇₀) is first threaded by α-CDs, leading to the formation of metastable micelles. After stabilizing the metastable micelles by shell cross-linking with poly(ethylene oxide)-b-poly(acrylic acid) (PEO₁₁₄-b-PAA₅₀), α-CDs are removed and the expected structure, polymeric vesicle, is achieved. On the contrary, only spherical micelles are formed in the similar conditions without the assistance of α-CD. Therefore, α-CDs, which act as chaperones, guide the self-assembly of block copolymers in the expected pathway.     

Self-assembly of rod-terminally tethered three-armed star-shaped coil block copolymer: Investigation of the presence of the branching in the coil to the self-assembled behavior

Self-assembled behavior of rod-terminally tethered three-armed star-shaped coil block copolymer melts was studied by applying self-consistent-field lattice techniques in three-dimensional (3D) space. Similar to rod-coil diblock copolymers, five morphologies were observed, i.e., lamellar, perforated lamellar, gyroidlike, cylindrical and sphericallike structures, while the distribution of the morphologies in the phase diagram was dramatically changed with respect to that of rod-coil diblock copolymers. The perforated lamella was replaced by the cylinder when f_rod = 0.45, and the lamella was replaced by the perforated lamella when f_rod = 0.5 when the arms A₁ and A₂ had an equal length and the volume fraction of A₃ arm was low enough. Simulations were also performed when the arms A₁ and A₂ had unequal lengths. These results demonstrate that simple branching in the coil induces interesting microphase transitions.     

Novel hybrid block copolymer nanocarrier systems to load lipophilic drugs prepared by microphase inversion method

Nanoparticles based on block copolymers of oligosaccharides [β-cyclodextrin (βCyD) and maltoheptaose (Mal₇)] and poly(ε-caprolactone) (PCL) were prepared by microphase inversion method. Zeta-potential, particle size measurements and morphological analysis of drug-free and drug-loaded nanoparticles were performed by using, respectively, laser-doppler anemometry, dynamic and static light scattering and transmission electron microscopy. ρ-Ratio values were correlated with transmission electron microscopy observations. Both types of amphiphilic block copolymers, βCyD-b-PCL_5k and Mal₇-b-PCL_5k, self-assembled in water to form spherical vesicles, presented a hydrodynamic diameter of 72 and 34 nm, respectively. The incorporation of drugs into nanoparticles did not affect significantly the particle size for βCyD-b-PCL_5k-based nanoparticles with progesterone, unlike the other tested systems. On the other hand, all nanoparticles (with and without drug) were negatively charged. Both nanoparticulate systems showed high drug loading efficiency (higher than 95%), confirming their suitability as delivery system for lipophilic drugs.     

Dielectric properties of polymer nanoparticle composites

Well-dispersed high dielectric permittivity titanium dioxide (TiO₂) nanoparticles were synthesized utilizing a block copolymer as a template. The nanoparticles were confined within microphase separated domains of sulfonated styrene-b-(ethylene-ran-butylene)-b-styrene (S-SEBS) block copolymers. A crosslinker (vinyltrimethoxysilane) was incorporated into the block copolymer matrices in order to decrease the dielectric loss from the free sulfonic acid groups. Dynamic mechanical analysis experiments confirmed that nanoparticles and crosslinker were confined within the crosslinked sulfonated styrene blocks and had no effect on the chain relaxation behavior of [ethylene-ran-butylene] blocks. Dielectric experiments showed that higher permittivity composites can thus be obtained with a significant decrease in loss tan δ (<0.01) when crosslinked with vinyltrimethoxysilane.     

Organic/inorganic hybrid materials from polypeptide-based block copolymers

Novel organic/inorganic hybrid material was synthesized from poly(acrylazapropyl-trimethoxysilane)-b-poly(N_ε-trifluoroacetyl-l-lysine) (P(AAPTMS)-b-P(TLL)) block copolymer using the sol–gel process. The treatment with ammonia solution permitted the hydrolysis of both trifluoro acetyl and trimethoxysilyl groups of the hydride copolymer followed by the condensation of the silanol groups, leading to cross-linked copolymers. The resulting cross-linked hybrid material was characterized using FT-IR, ²⁹Si NMR, DSC, TGA, and environmental scanning electron microscopy. These techniques evidenced that a siloxane network was obtained. Amphiphilic polypeptide/inorganic hybrid copolymers were achieved and self-organized as particles in water.     

Physical properties of poly(cyclohexyl methacrylate)-b-poly(iso-butyl acrylate)-b-poly(cyclohexyl methacrylate) triblock copolymers synthesized by controlled radical polymerization

The microphase segregation of different poly(cyclohexyl methacrylate)-b-poly(iso-butyl acrylate)-b-poly(cyclohexyl methacrylate), PCH-b-PiBA-b-PCH, triblock copolymers obtained by atom transfer radical polymerization has been evaluated by dynamic mechanical thermal analysis through location of the two relaxations ascribed to cooperative motions of each block. Additionally, other secondary relaxations have been found, whose characteristics are also dependent on molecular weight of outer and rigid segments. The length of these hard blocks influences significantly the stiffness and microhardness found in these triblock copolymers. These two mechanical parameters increase as molecular weight of poly(cyclohexyl methacrylate) does. The morphological aspects have been examined by small angle X-ray scattering and atomic force microscopy.