Tuning nanoscopic self‐assembly of diblock copolymer blends on a two‐dimensional interface

Spreading amphiphilic diblock copolymers on a two‐dimensional liquid interface has been observed to produce nanoscale features via self‐assembly. Here, we develop a model that incorporates the effects of polymer entanglement and surface diffusion in polymer blends to quantitatively predict the size of experimentally observed structures. Simulations show that different polymers in the blend cooperate to self‐assemble into nanoscale features of varying sizes. Characteristic nanoscopic dimensions can be tuned by adjusting two easily controllable macroscopic quantities: the blend composition and the initial surface concentration. Theoretical predictions are in agreement with experimentally measured feature dimensions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011     

Effect of sequence structure on wetting behaviors of fluorinated methacrylate polymers based on perfluorohexylethyl methacrylate and stearyl acrylate

Due to the non-crystalline properties of short chain perfluoroalkyl groups,using short chain perfluoroalkyl to stabilize low surface free energy polymers has been a challenging task.In this study,we prepare a series of random copolymers poly(perfluorohexylethyl methacrylate)-co-poly(stearyl acrylate) (P13FMA-co-PSA) and block copolymers poly(perfluorohexylethyl methacrylate)-b-poly(stearyl acrylate) (P13FMA-b-PSA),and systematically investigate the effects of the sequence structure and the content of 13FMA of the fluorinated copolymers on surface free energy and surface reorganization.Static/dynamic contact angle goniometry and water/oil repellency analyses demonstrate that the random polymer P13FMA-co-PSA could not achieve low surface free energy and low surface reorganization at the same time.In contrast,for the block copolymer P13FMA-b-PSA,both low surface free energy and low surface reorganization are acquired simultaneously.The results of X-ray photoelectron spectroscopy (XPS),dynamic contact angle goniometry and differential scanning calorimetry (DSC) reveal the above-mentioned properties.The consecutive 13FMA segments improve the surface fluorine density,while the consecutive SA chains enhance the crystallinity of the SA segments,and further hinder the surface reorganization of the perfluoroalkyl groups.Therefore,P13FMA-b-PSA exhibits a higher utilization efficiency of fluorine atoms and a better structural stability than P13FMA-co-PSA.     

Head‐to‐head polymers

Head‐to‐head (H–H) linkages were observed in addition and condensation polymers. Pure H–H polymers of polyolefins, poly(vinyl halides), and polyacrylates were prepared, and the fundamental polymer properties were determined. They included mechanical, spectral, thermal, and degradation behaviors. These properties were compared with those of the traditional head‐to‐tail polymers. Blends of H–H polymers were also studied. The thermal and thermal‐degradation behaviors of the blends were also investigated. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 4013–4022, 2000     

Designing superhydrophobic surface based on fluoropolymer–silica nanocomposite via RAFT‐mediated polymerization‐induced self‐assembly

Superhydrophobic surfaces (SHS) find versatile applications as coatings due to their very high water‐repellency, self‐cleaning, and anti‐icing properties. This investigation describes the preparation of a SHS from surfactant‐free hybrid fluoropolymer latex. In this case, reversible addition‐fragmentation chain transfer (RAFT) polymerization was adopted to prepare a copolymer of 4‐vinyl pyridine (4VP) and vinyl triethoxysilane (VTES), where the pyridine units were quaternized to make the copolymer soluble in water. The copolymer was further used as a macro‐RAFT agent to polymerize 2,2,2‐trifluoroethyl methacrylate (TFEMA) in a surfactant‐free emulsion via polymerization‐induced self‐assembly (PISA). The macro‐RAFT agent contained a small amount of VTES as co‐monomer which was utilized to graft silica nanoparticles (SNPs) onto the P(TFEMA) spheres. The film prepared using the nanocomposite latex exhibited a nano‐structured surface as observed by SEM and AFM analyses. Surface modification of the film with fluorinated trichlorosilane produced an SHS with a water contact angle (WCA) of 151.5°. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 266–275     

Well‐defined thermosensitive,water‐soluble polyacrylates and polystyrenics with short pendant oligo(ethylene glycol) groups synthesized by nitroxide‐mediated radical polymerization

We report the synthesis and thermosensitive properties of well‐defined water‐soluble polyacrylates and polystyrenics with short pendant oligo(ethylene glycol) groups. Four monomers, methoxydi(ethylene glycol) acrylate (DEGMA), methoxytri(ethylene glycol) acrylate (TEGMA), α‐hydro‐ω‐(4‐vinylbenzyl)tris(oxyethylene) (HTEGSt), and α‐hydro‐ω‐(4‐vinylbenzyl)tetrakis(oxyethylene) (HTrEGSt), were prepared and polymerized by nitroxide‐mediated radical polymerization with 2,2,5‐trimethyl‐3‐(1‐phenylethoxy)‐4‐phenyl‐3‐azahexane as an initiator. Kinetics and gel permeation chromatography analysis showed that the polymerizations were controlled processes yielding polymers with controlled molecular weights and narrow polydispersities. All polymers could be dissolved in water, forming transparent solutions, and undergo phase transitions when the temperature was above a critical point. The thermosensitive properties were studied by turbidimetry and variable‐temperature ¹H NMR spectroscopy. The cloud points of the polymers of DEGMA, TEGMA, HTEGSt, and HTrEGSt were around 38, 58, 13, and 64 °C, respectively. For all four polymers, the cloud point increased with decreasing concentration and increasing molecular weight in the studied molecular weight range of 5000–30,000 g/mol. The removal of the nitroxide group from the polymer chain end resulted in a higher cloud point. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2454–2467, 2006     

Polyurethane–oligo(phenylenevinylene) random copolymers: π‐Conjugated pores,vesicles, and nanospheres via solvent‐induced self‐organization

We report a new series of polyurethane–oligo(phenylenevinylene) (OPV) random copolymers and their self‐assembled nanomaterials such as pores, vesicles, and luminescent spheres. The polymers were synthesized through melt transurethane process by reacting a hydroxyl‐functionalized OPV with diurethane monomer and diol under solvent‐free and nonisocyanate conditions. The amount of OPV was varied up to 50 mol % in the feed to incorporate various amounts of π‐conjugated segments in the polyurethane backbone. The π‐conjugated segmented polymers were subjected to solvent induced self‐organization in THF or THF+water to produce variety of morphologies ranging from pores (500 nm to 1 μm) to spheres (100 nm to 2 μm). Upon shining 370‐nm light, the dark solid nanospheres of the copolymers transformed into blue luminescent nanoballs under fluorescence microscope. The mechanistic aspects of the self‐organization process were studied using solution FTIR and photophysical techniques such as absorption and emission to trace the factors which control the morphology. FTIR studies revealed that the hydrogen bonding plays a significant role in the copolymers with lower amount of OPV units. Time resolved fluorescent decay measurements of copolymers revealed that molecular aggregation via π‐conjugated segments play a major role in the samples with higher OPV content in the random block polymers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 46: 5897–5915, 2008     

Hyperbranched polymers as scaffolds for multifunctional reversible addition–fragmentation chain‐transfer agents: A route to polystyrene‐core‐polyesters and polystyrene‐block‐poly(butyl acrylate)‐core‐polyesters

Polydisperse hyperbranched polyesters were modified for use as novel multifunctional reversible addition–fragmentation chain‐transfer (RAFT) agents. The polyester‐core‐based RAFT agents were subsequently employed to synthesize star polymers of n‐butyl acrylate and styrene with low polydispersity (polydispersity index < 1.3) in a living free‐radical process. Although the polyester‐core‐based RAFT agent mediated polymerization of n‐butyl acrylate displayed a linear evolution of the number‐average molecular weight (M_n) up to high monomer conversions (>70%) and molecular weights [M_n > 140,000 g mol^?1, linear poly(methyl methacrylate) equivalents)], the corresponding styrene‐based system reached a maximum molecular weight at low conversions (≈30%, M_n = 45,500 g mol^?1, linear polystyrene equivalents). The resulting star polymers were subsequently used as platforms for the preparation of star block copolymers of styrene and n‐butyl acrylate with a polyester core with low polydispersities (polydispersity index < 1.25). The generated polystyrene‐based star polymers were successfully cast into highly regular honeycomb‐structured microarrays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3847–3861, 2003     

Small molecule self‐assembly in polymer matrices

Using small molecules in polymer matrices is common in applications such as (i) plasticizing polymers to modify the glass transition and mechanical properties and (ii) dispersion of photoactive or electroactive small molecules in polymer matrices in organic‐electronic devices Aggregation of these small molecules and phase separation leading to crystallization often cannot be morphologically controlled. If these are designed with self‐assembling codes such as hydrogen bonding or aromatic interactions, their phase separation behavior would be distinctly different. This review summarizes the studies on morphologies in such situations, such as (i) sub‐surface assembly in polymer matrices, (ii) controlled polymerization‐induced phase separation to create polymer blends, (iii) using the polymer to direct the assembly of small molecules in liquid crystalline devices, (iv) functionalizing a polymer with self‐assembling small molecules to cause organo‐gelation which the polymer itself would not by itself, and (v) using such systems as templates to create porous polymer structures. Organic–inorganic hybrids using polymers as templates for nanostructures and imprinted porous membranes is an emerging area. Since self‐assembly is one of the dominating area of research with respect to both small molecules, polymers as well as the combination of the two, this review summarizes the studies on the aforementioned topics. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018 , 56, 451–478     

Recent advances in the solution self‐assembly of amphiphilic “rod‐coil” copolymers

Solution self‐assembly of amphiphilic “rod‐coil” copolymers, especially linear block copolymers and graft copolymers (also referred to as polymer brushes), has attracted considerable interest, as replacing one of the blocks of a coil‐coil copolymer with a rigid segment results in distinct self‐assembly features compared with those of the coil‐coil copolymer. The unique interplay between microphase separation of the rod and coil blocks with great geometric disparities can lead to the formation of unusual morphologies that are distinctly different from those known for coil‐coil copolymers. This review presents the recent achievements in the controlled self‐assembly of rod‐coil linear block copolymers and graft copolymers in solution, focusing on copolymer systems containing conjugated polymers, liquid crystalline polymers, polypeptides, and polyisocyanates as the rod segments. The discussions concentrate on the principle of controlling over the morphology of rod‐coil copolymer assemblies, as well as their distinctive optical and optoelectronic properties or biocompatibility and stimuli‐responsiveness, which afford the assemblies great potential as functional materials particularly for optical, optoelectronic and biological applications. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 1459–1477     

Synthesis,polymerization, and curing of N‐substituted citraconimidyl acrylate

Several N‐(substituted phenyl) citraconimides containing phenolic hydroxyl groups (I) were prepared. I were esterified with acryloyl chloride producing the corresponding acrylate esters (II). II were free radically polymerized yielding linear polyacrylates (III). The citraconimidyl vinyls did not participate in the polymerization. The resulting polymers (III) were cured thermally or through the crosslinking agent N,N‐(p‐phenylene)dimaleimide. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 427–433, 1999     

SET‐LRP of acrylates in the presence of radical inhibitors

The Cu(0)/Me₆‐TREN‐catalyzed single‐electron transfer mediated living radical polymerization (SET‐LRP) of methyl acrylate in the presence of the classic 4‐methoxyphenol free radical inhibitor was investigated. Kinetic experiments, combined with ¹H NMR, and MALDI‐TOF MS analysis of the resulting polyacrylates demonstrated that SET‐LRP is a robust synthetic method that does not require the purification of the monomers to remove the radical inhibitor. It is anticipated that these results will contribute to the expansion of technological and fundamental applications of SET‐LRP since it allows the synthesis of polymers with a structural perfection that previously was not accessible by any other method, starting from unpurified monomers, solvents, initiators, and ligands. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3174–3181, 2008     

Synthesis of high‐order multiblock core cross‐linked star polymers

Core cross‐linked star (CCS) polymers with radiating arms composed of high‐order multiblock copolymers have been synthesized in a one‐pot system via iterative copper‐mediated radical polymerization. The employed “arm‐first” technique ensures the multiblock sequence of the macroinitiator is carried through to the star structure with no arm defects. The versatility of this approach is demonstrated by the synthesis of three distinct star polymers with differing arm compositions, two with an alternating ABABAB block sequence and one with six different block units (i.e. ABCDEF). Owing to the star architecture, CCS polymers in which the arm composition consists of alternating hydrophilic–hydrophobic (ABABAB) segments undergo supramolecular self‐assembly in selective solvents, whereas linear polymers with the same block sequence did not yield self‐assembled structures, as evidenced by DLS analysis. The combination of microstructural and topological control in CCS polymers offers exciting possibilities for the development of tailor‐made nanoparticles with spatially defined regions of functionality. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 135–143     

Preparation of few‐layer two‐dimensional polymers by self‐assembly of bola‐amphiphilic small molecules

Two bola‐amphiphilic small molecules, based on the diphenylanthracene skeleton structure, namely, BASM‐1 and its functionalized small molecule BASM‐2 , were designed and synthesized. The self‐assembly behavior and mechanism of these two molecules in aqueous solution were studied. The supramolecular two‐dimensional (2D) layer and the covalent 2D polymers were, respectively, prepared by these two molecules. What is more, the transverse size of the covalent 2D polymer laminates increased with the extension of the polymerization time. Atomic force microscopy results showed that both free‐standing single‐layer 2D polymers and few layer laminates with two to three molecular layers were obtained. So our work provides a simple and efficient method for directly preparing independent both supramolecular 2D polymers and covalent 2D polymers in liquid phase which is of great significance. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1748–1755     

Managing polymer surface structure using surface active block copolymers in block copolymer mixtures

Surface coatings were prepared from semifluorinated monodendron surface‐active block copolymers (SABC) and a thermoplastic elastomer (TPE) [poly(styrene‐b‐ethylene butylene‐b‐styrene)] by either spin‐casting a bilayer structure or by blending. The surface of these coatings was characterized by contact angle measurements, scanning force microscopy (SFM) and near‐edge X‐ray absorption fine structure (NEXAFS) methods. Both bilayers and blends resulted in very low energy surfaces under the right processing conditions and the liquid crystallinity of the semifluorinated monodendrons gave rise to temporally stable, non‐reconstructing surfaces in water. However for small thicknesses of the SABC top layer or for low SABC content blends, SFM shows islands of the fluorinated block of the SABC and incomplete surface coverage of the TPE, an observation confirmed by NEXAFS analysis. Very high water contact angles were produced by even modest amounts of SABC in either case but to achieve low contact angle hysteresis, it was necessary to produce uniform surface coverage by the SABC. Such uniform coverage can be accomplished by spin casting a top layer of SABC as thin as 60 nm in the bilayer case but at least 10 wt% SABC in TPE combined with drop casting of a hot solutions is needed for the blends to achieve equivalent surface structure and properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 411–420, 2004     

含氟丙烯酸酯三元共聚物乳液的研究

以丙烯酸全氟烷基酯 (ZonylTM)、甲基丙烯酸甲酯 (MMA)、丙烯酸丁酯 (BA)为原料 ,在阴离子乳化体系中制备了含氟丙烯酸三元共聚物乳液 .研究了聚合反应动力学、转化率的各种影响因素 ,得出了聚合速率方程 ,并得出反应的表观活化能 (Ea)为 5 0 75 8kJ mol.考察了乳液的稀释稳定性、贮存稳定性、离心稳定性、耐热、耐寒稳定性 ,及乳胶膜的吸水性和耐溶剂性 .并用Wilhelmy方法测定了乳胶膜与水的接触角 ,结果表明乳胶膜对水的抗浸润力大大提高     

Synthesis of semifluorinated block copolymers by atom transfer radical polymerization

Two sets of styrene‐based semifluorinated block copolymers, one with a perfluoroether pendant group and another with a perfluoroalkyl group, were synthesized by atom transfer radical polymerization. Microphase separation of the block copolymers was established by small‐angle X‐ray scattering and differential scanning calorimetry (DSC). DSC measurements also showed that the perfluoroether‐based polymer had a low glass‐transition temperature (?44 °C). Contact‐angle measurements indicated that the semifluorinated block copolymers had low surface energies (ca. 13 mJ/m²). These materials hold promise as low‐surface‐energy additives or surfactants for supercritical CO₂ applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 853–861, 2004     

Self‐emulsification and surface modification effect of fluorinated amphiphilic acrylate graft copolymers

We report on self‐emulsification and surface modification effect of novel fluorinated amphiphilic graft copolymers prepared with perfluoroalkyl acrylate and 2‐dimethylaminoethyl methacrylate using simple macromonomer technique and radical copolymerization. The interfacial properties of amphiphilic graft copolymers were characterized with light scattering, contact angle measurement, and X‐ray photoelectron spectroscopy. The preparation of fluorinated amphiphilic graft copolymer was verified using nuclear magnetic resonance and Fourier transform infrared spectroscopy. It was observed that the fluorinated amphiphilic graft copolymer has both strong hydrophobic and hydrophilic properties and shows self‐emulsification ability without addition of external surfactants. The graft copolymer shows very low surface energy even though the copolymer has low content of hydrophobic segment and better performance than random copolymer for low‐energy surface modification. The addition of small amount of the graft copolymer (0.1 wt %) into the base poly(methyl methacrylate) was sufficient to lower the surface energy less than that of poly(tetrafluoroethylene). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Water‐Soluble and pH‐Responsive Polymeric Nanotubes from Cyclic Peptide Templates

Water‐soluble organic nanotubes were prepared by convergently conjugating polymers of hydroxyethyl acrylate (HEA) and acrylic acid (AA) to self‐assembling cyclic octapeptides of alternating D and L chirality. The structure of the self‐assembled tubes was characterised in a number of polar solvents, and notably water, by using light scattering, TEM and small angle neutron scattering (SANS) techniques. In addition, the self‐assembly into tubes could be controlled by exploiting the pH responsiveness of acrylic acid polymers.     

Nanocrystalline cellulose/fluorinated polyacrylate latex via RAFT‐mediated surfactant‐free emulsion polymerization and its application as waterborne textile finishing agent

A simple method for nanocrystalline cellulose (NCC)/fluorinated polyacrylate was developed by RAFT‐mediated surfactant‐free emulsion polymerization, in which the nanocomposites formed a core‐shell spherical morphology. The influence of the content of NCC‐g‐(PAA‐b‐PHFBA) (AA was acrylic acid, HFBA was hexafluorobutyl acrylate) on the properties of latex and film were systematically studied. The monomer conversion, the tensile strength, and water–oil repellency of film increased first and then decreased, the latex particle size decreased first and then decreased, when the content of NCC‐g‐(PAA‐b‐PHFBA) increased from 1 to 6 wt %. Elongation at break and thermal stability distinctly decreased when the content of NCC‐g‐(PAA‐b‐PHFBA) gradually increased. XPS showed that the fluorine‐containing groups well concentrated at the film–air interfaces during the annealing process. SEM analysis revealed that the treated fiber had a rugged surface, and the treated fabric had an excellent water repellency. In addition, this green grafting method in water offered a new perspective for the fabrication of exceptional NCC‐based nanocomposites with NCC as the core and also helped to promote the potential applicability of NCC in a range of multipurpose applications. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1305–1314     

Spacer‐length‐dependent association in polymers with multiple‐hydrogen‐bonded end groups

Herein, we investigate the influence of spacer length on the homoassociation and heteroassociation of end‐functionalized hydrogen‐bonding polymers based on poly(n‐butyl acrylate). Two monofunctional ureido‐pyrimidinone (UPy) end‐functionalized polymers were prepared by atom transfer radical polymerization using self‐complementary UPy‐functional initiators that differ in the spacer length between the multiple‐hydrogen‐bonding group and the chain initiation site. The self‐complementary binding strength (K_dim) of these end‐functionalized polymers was shown to depend critically on the spacer length as evident from ¹H NMR and diffusion‐ordered spectroscopy. In addition, the heteroassociation strength of the end‐functionalized UPy polymers with end‐functionalized polymers containing the complementary 2,7‐diamido‐1,8‐naphthyridine (NaPy) hydrogen‐bond motif is also affected when the aliphatic spacer length is too short. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011