WO2017080357A1 - Detection of glass transition temperatures and visualization of phase-separated morphology - Google Patents

Abstract

Provided are a new detection method for glass transition temperatures of polymeric materials and a facile visualization method for the phase-separated morphology of polymer blends in spin-coated thin films by utilizing Aggregation-Induced Emission dyes as fluorescent probes. A prototype device for measurement of glass transition temperature is also designed and developed.

Description

Application of AIEgens Doping with Polymers:

Detection of Glass Transition Temperatures and Visualization of Phase-Separated Morphology

FIELD OF THE INVENTION 

This invention relates to a new detection method for glass transition temperatures of polymeric materials,and a facile visualization method for the phase-separated morphology of polymer blends in spin-coated thin films by utilizing Aggregation- Induced Emission dyes as fluorescent probes. A prototype device for measurement of glass transition temperature is also designed and developed. BACKGROUND OF THE INVENTION  The glass transition is the reversible transition process from the hard, stiff and bristle glassy state to the soft, elastic and flexible rubbery state in polymer materials, which usually accompanied by significant changes of mechanic properties, viscosity, thermal- expansion coefficient, and specific heat. However, unlike melting or vaporization, glass transition is not a first order phase transition. It is rather a laboratory phenomenon extending over a range of temperature. Although segmental movement of polymer chains is the most accepted proposal, the real physical process of polymer chain movement during this subtle transition is still not completely understood by the polymer scientists. The investigation for glass transition is of great value for fundamental understanding of polymer physics down to molecular level. Besides, glass transition temperature (denoted as T_g) is one of the most crucial parameters for polymer materials in industrial applications because it directly affects the properties and performance of polymers. For example, rubbers like erases are used above its T_g because the soft and flexible properties are essential for them to function properly. Plastics as bottles, television shells and shatterproof windows are used below their T_g to maintain tough and strong mechanical properties.

Based on the changes of different physical properties during glass transition, there have been several techniques established to determine T_g of polymers, including dilatometry, dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). Dilatometry measures changes in sample length or volume as a function of temperature, which is simple and facile, but suffers from poor accuracy. DMA, mainly used for engineering materials, determines glass transition by testing mechanical properties of polymeric materials, but it usually requires massive samples (a few grams). Compared with the aforementioned methods, DSC monitors the changes of heat flow involved during the process and is the most commonly used technique. In DSC results, there is usually baseline shifting, rather than sharp peaks, of heat flow during glass transition. T_g is then determined by the half-height of two baselines. However, because of some technical issues, including accurate heat flow measurement and baseline fluctuation, the results of DSC for glass transitions are usually ambiguous. For some polymers, such as poly(styrene-butadiene-styrene) (SBS), the heat flow involved in glass transition is very small, thus T_g is hard to be accurately determined.

Fluorescence is widely used for different kinds of chemosensing, imaging and process monitoring due to its fast response, high sensitivity and easy detection.Conventional fluorescent dyes mostly suffer from the aggregation-caused quenching (ACQ) effect, whose emission intensity drops with the increase of dye concentration. The ACQ effect results in poor photo-stability and photo-bleaching, which is harmful for fluorescent imaging. In recent decades, there is a new class of luminogen termed as Aggregation-Induced Emission molecule (AIEgen), which have weak emission in solution but demonstrate high emission intensity in aggregated state. The working principle of AIE, restriction of intra-molecular motion (RIM), makes AIEgens sensitive to micro-environmental changes and perfect candidates for detection of glass transition of polymers. When AIEgens are doped in polymer films, their intramolecular motions are restricted, thus emitting strong fluorescence in rigid polymer matrix before T_g. However, at temperature higher thanT_g, segmental movement of polymer chains allows AIEgens to rotate or vibrate more freely. These motions consume energy in non-radioactive decay pathways, which lead to more rapid decay of fluorescent intensity after T_g. Therefore, the change of fluorescence decay rate can unambiguous reveal the onset of glass transition of polymers.Based on such emission distinction in different polymer environment, AIEgens are expected to be excellent fluorescent probes used for the detection of phase-separated blend morphology.

Blending is a well-known and common strategy in polymer technology. Compared with tedious syntheses of new polymers, which requires professionalresearchers or technicians, blending can achieve new materials with specific functionalities simplyby mixing two or more polymerstogether. The resulting polymer blends often possess more desirable structural and physical characteristics than those of individual homopolymers in the solid state.Nevertheless,most commercialpolymer blends, such as the blends of polystyrene (PS), polybutadiene (PB),polylactide (PLA), polymethylmethacrylate (PMMA), etc., are immiscible and will easilydemix, resulting in phase separation.For example, during the spin-coating preparation process of thin films of a binary polymer blend, the blend solution will undergo a rapid solvent evaporation and phase separation will occur to form a separated binary phase. Polymer blends haveplayed an important role in optoelectronic devices, in which the phase-separated morphologyand domain size of the resulting thin film has a direct effect on its mechanical and electrical properties, and thus greatly affects the device performance.Normally, the domain size of immiscible polymer blends is at the micrometer scale. In practical applications, polymer blend thin films are extensively used not only in plastic-based optoelectronics but also in packaging, drug-delivery systems, adhesives, ultrahigh density storage media, etc. Thus, the study of the phase-separated structureof polymer blends, especially those confined within thin films, is of great significance from both the academic and industrial aspects.

To evaluate thephase domain morphology, various types of microscopic and spectroscopic techniques have been applied, such as atomic force microscopy (AFM), lateral force microscopy (LFM), force modulation microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoemission electron microscopy (PEEM), scanning near-field optical microscopy (SNOM), etc. However, all these reported methodologies suffer from their intrinsic limitations. For example, AFM is one of the primary techniques used to determine domain structures with the capability of resolving topographic features in atomic scale. Nevertheless, it is not suitable to detect morphology at the micrometer scale and is expensive and time-consuming for industrial applications. Moreover, AFM suffers from the small single-scan image size and slow scanning speed,and high-quality thin films are usually required to reduce the interference of inherent roughness. The identification of polymer components in the heterogeneous sample is often realized indirectly either by their mechanical property differences or by selective phase removal by certain solvents.In terms of electron microscopy, SEM and TEM have been occasionally used to image the polymer phase-separated morphology, but their sample preparation procedures are troublesome and may irreversibly change or even damage the sample structures.When SEM is used to image polymer samples, special treatments, such as metal/carbon coatings, are required. For TEM analysis, elaborate preparation methods are needed to make the sample thin enough to be electron transparent, andchemical stainingis needed for some poor-contrast components. For instance, toxic osmium tetroxide vapor is employed to stain PB phase to provide contrast and reveal the polymer composition. Therefore, itis of great commercial research interest to develop a direct, high-contrast, and low-cost method to visualize the phase-separated blend morphology.

Concerning the facial sample preparation, easy operation, fast imaging, and little film damage, optical microscopy is a good choice to evaluate the micron-sized domain morphology. However, bright-field images might show misleading information from the inherent roughness of the films. Moreover, it often cannot provide enough information to unambiguously identify the blend composition due to its low penetration depth and poor contrast between two phases.Fluorescence is widely applied in chemo-/bio-sensing and imaging, due to its high sensitivity, big contrast, visible detection, and fast response. For light emitting polymer blends, which is a minority of polymer family, fluorescence microscopy has been occasionally used to visualize their phase separation.But how about the most common used and non-emissive polymer blends?

In order to develop fluorescence microscopy into a versatile tool for the morphology visualization of a wide scope of polymer blends, fluorescent dyes can be employed to label the polymer phases. As stated previously, when AIEgens are doped inpolymer blends, the dynamic motions of AIEgens will be different. Insoft rubbery polymer matrix, the segmental movement of polymer chains at room temperature will dissipate the exciton energy non-radiatively, thus leading to the weak emission signal. While in more rigid glassy polymer matrix, the intramolecular motions of AIEgens will be greatly restricted and induce the strong emissionemission.[G. Iasilli, A. Battisti, F. Tantussi, F. Fuso, M. Allegrini, G. Ruggeri, A. Pucci, Macromol. Chem. Phys.2014, 215, 499−506].Based on the emission distinction in different polymer environments, AIEgens are expected to be excellent fluorescent probes used for the detection of phase-separated blend morphology.

SUMMARY OF THE INVENTION 

In this invention, we design and establish a novel detection methodutilizing AIEgens as probes for glass transition of polymers. Meanwhile, we present a fluorescent method for the mapping of domain morphology of immiscible polymer blends utilizing uniqueAIEgens as the staining reagent. A series of AIEgens including tetraphenylethene (TPE), TPE2CN, TPAMPO, DNTPh, BTPE-PI, DPA-IQ, TPATPE, Silo-2Meand (R)- JR-5were selected to dope with various polymers and polymer blends. The structures of these AIEgens are given in Figure 1.

For T_g detection, the fluorescent images of doped films were monitored by camera at different temperatures.Using MATLAB program, the fluorescence intensity of the doped polymer films can be calculated based on grayscale from the pictures. The fluorescence intensity decreases steadily as temperature increase, while a significant change of decay rate was observed around T_g. Thus theT_g of a polymer can be unambiguously indicated by the lowest point of the second derivative of its fluorescent intensity against temperatures. This result is much clearer than that achieved by conventional DSC measurement, which shows the indistinct upward shift in the baseline during the heating cycle. Because of abovementioned advantages, we have established a simple, reliable and sensitive technique for the detection ofT_g of different polymeric materials by utilizing AIEgens and computer programing. This measurement technique is termed as ADEtect.

Based on this method, we have designed and developed a prototype device for glass transition detection of polymer materials using AIEgens as fluorescent probes. Several advantages such as low cost, simple sample preparation, easy operation, high accuracy and auto-data processing can be achieved. For morphology visualization, through the simple three-step procedure:physically mixing AIEgens with polymers, preparing thin films of the blend solutionby spin-coating method and subsequent imaging via fluorescent microscopy, high-contrast and unambiguous morphology image could be readily obtained. Regarding the working mechanism, they can be classified into three categories:(i) AIEgens TPE and TPE2CN exhibit different emission intensities(brightness) inpolymers with different rigidity, whichallows them to identify the phase-separated structures of PS/PB blends.(ii) TPAMPO and DNTPh show different emission wavelengths (color) in polymers with different polarities; thus they can be used to differentiate the domain morphology of PB/PEG, PB/PS and PB/PMMA blends. (iii) Specially, for the AIEgen of (R)-JR-5, it can distinguish the morphologies ofpolymer blends that were composed of a non- coordinating and a Lewis-basic or hetero-atom containing polymer, such as PS/PEG and PS/PLA blends, by on-off emission.Its working mechanism is chemical sensing due toits Lewis acidity. The reversible coordination to Lewis bases results in a breakage of a weak intramolecular boron-nitrogen single-bond leading to quenching of a long-wavelength band both in absorption and emission.

Compared to current analytical methods, this method enjoys several advantages. For example, (i) itis much cheaper and faster, and is easy to operate;(ii) the domain composition and size can be directly distinguished with high-contrast by fluorescence difference at the micrometer scale; and (iii) it has facile sample preparation procedure andlittle film damage.With these advantages, we believe this work willfacilitate the development of novel visualization techniques for polymer phase separation, whichis of greatconsiderable technological andcommercial interest. BRIEF DESCRIPTION OF FIGURES AND TABLES 

Figure 1. The structures of AIEgens.

Figure 2.Illustration ofEquipment Setup ofADEtectMeasurement and Data Processing Table 1. Summary of selected polymers

Figure 3.(A)Grayscale loss caused byphotobleaching of DPA-IQ doped PS-2 film at room temperature under handheld UV lamp excitation. Excitation Wavelength: 365 nm.(B) Grayscale of DPA-IQ powders at different temperatures. Heating rate: 6 ^oC/min. (C) Stability test of DPA-IQ doped PS-2 at heating rate of 6 ^oC/min.

Figure 4.Photos representatives of DPA-IQ doped polymethylmethacrylate(PMMA) film taken under 80, 90, 100, 110, 120, 130, 140, 150, 160 ^oC.

Figure 5.(A) Intensity of DPA-IQ doped PMMA film at different temperatures and the associated fitting curve. Heating rate: 6 ^oC/min; (B) Second differentiation of the fitting curve in (A) to reflect the change in the emission intensity at different temperature. Figure 6.Photos representatives of DPA-IQ doped PS-2 film taken under 80, 90, 100, 110, 120, 130, 140, 150, 160 ^oC

Figure 7.(A) Intensity of DPA-IQ doped PS film at different temperatures and the associated fitting curve. Heating rate: 6 ^oC/min; (B) Second differentiation of the fitting curve in (A) to reflect the change in the emission intensity at different temperature

Figure 8.Photos representatives of DPA-IQ doped polyvinyl chloride (PVC) film taken under 80, 90, 100, 110, 120, 130, 140, 150, 160 ^oC.

Figure 9.(A) Intensity of DPA-IQ doped PVC film at different temperatures and the associated fitting curve. Heating rate: 6 ^oC/min; (B) Second differentiation of the fitting curve in (A) to reflect the change in the emission intensity at different temperature. Figure 10.Photos representatives of DPA-IQ doped poly(styrene-butadiene-styrene) (SBS) film taken under 80, 90, 100, 110, 120, 130, 140, 150, 160 ^oC.

Figure 11.(A) Intensity of DPA-IQ doped SBS film at different temperatures and the associated fitting curve. Heating rate: 6 ^oC/min; (B) Second differentiation of the fitting curve in (A) to reflect the change in the emission intensity at different temperature. Figure 12.DSC (second heating cycle) thermograms of (A) PMMA, (B) PS, (C) PVC, (D)SBS powders under nitrogen at a heating rate of 10 ^oC/min.

Table 2. Comparison of fluorescent results and DSC results for different polymers

Figure 13.Intensity of DPA-IQ doped PMMA film at different temperatures and the associated fitting curve. Heating rate: (A) 3^oC/min, (B) 6^oC/min, (C) 12^oC/min;DSC (second heating cycle) thermograms of PMMA powders under N₂ at a heating rate of (D) 3 ^oC/min, (E) 6 ^oC/min, (F) 12 ^oC/min.

Table 3.Summary of glass transition temperature results of PMMA at different heating rates Figure 14. Grayscale of (A) Silo-2OMe doped PMMA film, (B) TPA-BMO, (C) DPA- IQ, (D)TPATPE, (E) BTPE-PI and (F) Perylene doped PS-2 film at different

temperatures. Heating rate: 6 ^oC/min.

Scheme 1. Synthetic route of DNTPh.

Figure 15.Emission spectra of DNTPh in solid state. Excitation wavelength: 400 nm. Figure 16.(A) Emission spectra of DNTPh in THF/water mixtures with different water fractions (f_w). (B) Plot of relative emission intensity (I/I₀) versus the composition of the aqueous mixture of DNTPh. I₀ = intensity at f_w = 0%.Solution concentration: 10 μM; excitation wavelength: 400 nm.

Figure 17.Absorption spectra of DNTPh in different solvents. Solution concentration: 10 μM.

Figure 18.Emission spectra of DNTPh in different solvents. Solution concentration: 10 μM; excitation wavelength: 400 nm.

Table 4. Optical properties of DNTPh in different solvents^a Figure 19.Lippert-Mataga plot of the relation between Stokes shift with solvent polarity (Δf) for DNTPh.

Figure 20. Sample preparation and experimental workflow.

Figure 21. XRD curves of 1.0 wt% TPE/polymers and TPE.

Figure 22. Emission spectra of 1 wt% TPE in polymer films obtained by the spin-coating method. Excitation at 320 nm. Inset: the associated photos taken under 365 nm UV irradiationwith a hand-held UV-lamp.

Figure 23. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% TPE doped thin films of PS, PB and PS/PB = 50/50 (w/w), respectively.

Figure 24. (A) SEM image, (B) bright-field image and (C) fluorescent image of 1.0 wt% TPE doped thin films of PS, PB and PS/PB = 50/50 (w/w) blend, respectively.

Figure 25. XRD curves of (A) 0.1 wt%/polymers and TPE; (B) 5.0 wt%/polymers and TPE.Inset: photo of 5.0 wt% TPE doped thin film of PB taken under room light.

Figure 26. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 0.1 wt% TPE doped thin films of PS, PB and PS/PB = 50/50 (w/w), respectively. Figure 27. Fluorescent images of 1.0 wt% TPE doped thin films of PS, PB and PS/PB blends with different PB volume fractions (w_PB).

Figure 28. Emission spectra of 1 wt% TPE2CN in polymer films. Excitation at 400 nm. Inset: the associated photos taken under365 nm UV irradiationwith a hand-held UV-lamp. Figure 29. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% TPE2CN doped thin films of PS, PB and PS/PB = 50/50 (w/w), respectively.

Figure 30. Emission spectra of 1 wt% TPAMPO in polymer films. Excitation at 410 nm. Inset: the associated photos taken under 365 nm UV irradiationwith a hand-held UV- lamp.

Figure 31. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% TPAMPO doped thin films of PS, PB and PS/PB = 50/50 (w/w), respectively.

Figure 32. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% TPAMPO doped thin films of PMMA, PB and PMMA/PB = 50/50 (w/w), respectively.

Figure 33. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% TPAMPO doped thin films of PEG, PB and PEG/PB = 50/50 (w/w), respectively.

Figure 34. Emission spectra of 1 wt% DNTPh in polymer films. Excitation at 410 nm. Inset: the associated photos taken under365 nm UV irradiationwith a hand-held UV-lamp. Figure 35. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% DNTPh doped thin films of PS, PB and PS/PB = 50/50 (w/w), respectively.

Figure 36. (A−C) Bright-field images, (A’−C’) fluorescent images and (A’’−C’’) merged images of the corresponding bright-field and fluorescence images of 1.0 wt% DNTPh doped thin films of PMMA, PB and PMMA/PB = 50/50 (w/w), respectively.

Scheme 2.Synthesis of (R)-JR-5. (a) B₂pin₂, [PdCl₂(dppf)], KOAc, THF, 65 °C, 18 h, 84%; (b) KHF_2(aq), 1:1 MeOH/THF, 22 °C, 15 min, 92%; (c) LiOH•H₂O, 2:1 MeCN/H₂O, 22 °C, 24 h, 100%; (d) 1.1-methyl-1-phenylhydrazine, MgSO₄, CHCl₃, 22 °C, 30 min; 2. (R)-BINOL, 70 °C, 2 d, 73%. Figure37.ORTEP plot of (R)-JR-5; orthorhombic, space group P2₁2₁2₁. Arbitrary numbering, atomic displacement parameters obtained at 100 K are drawn at 50% probability level.

Figure 38.(A) UV-vis spectra of (R)-JR-5 (10^–5 M) in THF (dashed line) and 1,2- dichloroethane (DCE, solid line); (B) CD spectrum of (R)-JR-5 (10^–5 M) in THF.

Scheme3. Proposed equilibrium between a Lewis base (here the solvent THF) and (R)- JR-5.

Figure39. DFT-computed (B3LYP/6-31G(d)) HOMO (–4.96 eV) and LUMO (–2.28 eV) of (R)-JR-5.

Figure 40. (A) PL spectra of (R)-JR-5 in different c-hexanolfractions (f_cH) in THF/c- hexanol mixtures. (B) Plot of I/I₀ versus f_cH. I= PL intensity of (R)-JR-5 in a pure THF solution at 406 and 442 nm. Concentration: 10 μM; Excitation wavelength: 360 nm. Figure 41. PL spectrum of a PS-film doped with 10% (R)-JR-5. Ex.: 480 nm. Figure 42. PS/PEG = 75/25 (w/w) doped with (R)-JR-5 (2%) in bright field (above) and under excitation at 400–440 nm (below).

Figure 43. PLA/PS =50/50 (w/w)doped with (R)-JR-5 in bright field (above) and under excitation at 400–440 nm (below).

Figure 44. Stern-Volmer-Plots of (+)-menthol (triangles, dashed line) and (–)-menthol (squares, solid line).

Figure 45. Qualitative PL spectra of a pristine film (solid line) of (R)-JR-5 in PS (10%) and after treatment with a solution (30 μL, 8 mM in DCE) of (+)-menthol (pointed line) and (–)-menthol (dashed line).

DETAILED DESCRIPTION OF THE PREFERRED 

EMBODIMENTS 

The following detailed description of the invention is provided to aid those skilled in the art in practicing the present invention. However, the following detailed description of the invention should not be constructed to unduly limit the present invention. Variations and modifications in the embodiments discussed may be made by these of ordinary skill in the art without departing from the scope of the present inventive discovery. 1. Experiment setup and justification for T_g detection

The experiment setup is made of two parts: a program-controlled heating stage with UV handheld lamp, and a computer-controlled camera detector, as illustrated in Figure2. AIEgens DPA-IQ, TPA-BMO TPATPE, Silo-2OMe and BTPE-PI were synthesized according to previous reported literatures. General procedures for sample preparation, glass transition measurement and data processing are as follows. Homogeneous solution of polymer with 1.0 wt% of AIEgen was preparedby sonication. The AIEgen-doped polymer thin film, prepared by spin-coating, was placed on the heating stage under UV excitation and heated for a range of temperature with a constant heating rate.The ISO and exposure time were set according to the emission intensity of each AIEgen-doped polymer thin film respectively.After the camera captured the images of polymer film at different temperature, a Matlab program is designed and used to calculate the grayscale values of the corresponding images. The grayscale is calculated based on RGB value, using Equation (1).

An R language program is designed and used to produce the fitting curve for the grayscale data set. The fitting curve is using Spline as described in Equation (2).

be a sequence of observations, modeled by the relation The smoothing spline estimate of the function f is defined to be the

minimizer (over the class of twice differentiable fu

nctions) o

The corresponding second differentiation curve to determine the turning point of grayscale intensity. The temperature for minimum of second derivative, which corresponds to the turning point of grayscale, is termed as the T_gof polymer.

Photobleach effect of UV excitation on AIE molecule is studied bymeasuring the grayscale intensityof DPA-IQ doped PS-2 film at room temperature under handheld UV lamp excitation It shows a steady decline of grayscale intensity upon heating for about 5% loss without sudden change (Figure 3A). Temperature effect on fluorescence of DPA-IQ powders is also studied, showing a steady linear decline of fluorescence intensity (Figure 3B). This has proved that AIE molecules such as DPA-IQ is thermally stable, thus are excellent candidates as fluorescent probes detecting glass transition of polymers. The stability of ADEtect is studied byDPA-IQ doped PS-2 (Figure 3C) 2. T_g measurements of different polymers

Followings are examples of utilizing the above-established measurement platform to detect T_g of different polymer materials with AIEgens as fluorescent probes. Several commercial available and commonly used polymers, including polymethylmethacrylate (PMMA), polystyrene (PS), polyvinyl chloride (PVC) and poly(styrene-butadiene- styrene) SBS were chosen and measured. DPA-IQ is chosen as the standard AIEgen probe for glass transition detection because of its high quantum yield in the solid state, high thermal stability and photo stability.

The DPA-IQ doped PMMA thin film was prepared according to the previous general procedure and the fluorescent images at different temperatures were captured camera. Photos representatives of DPA-IQ doped PMMA film taken under 80, 90, 100, 110, 120, 130, 140, 150, 160 ^oC were shown in Figure 4.From the images, we can clearly observe the decrease of fluorescent intensity, or brightness, especially after 120 ^oC. The brightness of images can be quantified as grayscale intensity by Matlab program. Thus the quantified data of grayscale intensity at different temperatures was obtained accordingly and plotted in Figure 5A. It is very obvious that there is a steady decay of grayscale intensity before ~120 ^oC and then the slot of decay suddenly changes after ~120 ^oC. The proposed working mechanism is described below. When DPA-IQ is doped into PMMA thin film, it is well dispersed in the polymer matrix. Upon heating, the thermal energy will cause DPA-IQ to rotate and vibrate more fiercely, leading to non- radioactive decay and the decrease of emission intensity. Before glass transition, polymer chain is immobile and the polymer matrix is very rigid, which will restrict the molecular motion of DPA-IQ. Therefore, the emission of DPA-IQ can only decreases in a slow rate upon heating. However, after glass transition, the segmental of polymer chain can start to move. The polymer matrix thus becomes soft and rubbery, providing more free volume for rotation and vibration of DPA-IQ. What’s more, the segmental movement of polymer chains may further increase the molecular motion of DPA-IQ. The synergistic effect of soft matrix and segmental motion causes the more rapid decrease of fluorescent intensity of DPA-IQ. Based on the mechanism, the turning point of fluorescent intensity can be termed as glass transition temperature, aka T_g, of PMMA. In order to determine the turning point ambiguously, the second differentiation of the intensity fitting curve is plotted in Figure 5B. The temperature for minimum of second differentiation corresponds to the turning point of grayscale. Consequently, the T_gof PMMA is measured as 118.2 ^oC.

Similar procedures for sample preparation, measurement and data processing have been done for PS, PVC and SBS, providing T_gresults as 98.8, 85.1 and 95.3 ^oC respectively (Figure 6-11). The T_gs of above polymers were also measured by differential scanning calorimetry (DSC) as reference (Figure 12). The comparison of fluorescent results and DSC results of above polymers were summarized in Table 2. It is worth noting that the T_g of styrene block in SBS is usually hard to be determined by DSC, since the baseline shifting of heat flow is obscure (Figure 12D). This is because in room temperature, the rigid polystyrene block will form glassy“islands” which is surrounded by rubbery polybutadiene block. The heat flow involved in the glass transition of polystyrene block will also be absorbed by surrounding polybutadiene block, thus the detectable heat flow is very small, resulting in obscure baseline shifting in DSC measurement. On the contrary, when DPA-IQ is doped into SBS, the surrounding polybutadiene block won’t affect the fluorescent changes in polystyrene block during glass transition. Therefore, our fluorescent method can provide a clear and unambiguous T_g result for SBS.

In conclusion, the fluorescent results obtain from our method are very close to those obtained from DSC, verifying that our fluorescent method can detect the T_g. What’s more, the data plots of fluorescent method show much more distinct turning point, which can be unambiguously determined by second differentiation of grayscale intensity. This demonstrates the high sensitivity and accuracy of fluorescent results compared to baseline shifting of DSC measurement. The example of SBS illustrates the priority of fluorescent methods. 3. T_gmeasurements at different heating rate

Glass transition temperature is a second-order phase transition, which will be affected by thermal history, measurement condition et al. Thus T_g of polymer is a heating rate dependent parameter. Following are examples of T_gmeasurements of DPA-IQ doped PMMA at different heating rate (3 ^oC, 6 ^oC and 12 ^oC).

Similar procedures for sample preparation, measurement and data processing have been done. The results are shown in Figure 13A-C, providing T_gresults as 120.7, 118.2 and 113.0 ^oC for heating rate of 3 ^oC, 6 ^oC and 12 ^oC, respectively. The T_gs of PMMA were also measured at different heating rates by differential scanning calorimetry (DSC) as reference (Figure 13D-F). The comparison of fluorescent results and DSC results at different heating rates were summarized in Table 3. The results obtained by our fluorescent detection method are well match with the DSC results, showing the same trend. The T_g decreased along with the increasing of heating rate.

When compared more carefully between the shapes of the curves obtained by fluorescent method and DSC measurement, more information can be obtained. For one thing, the heat flow (mW) measured in DSC is closely related to measuring time. When the heating rate is slower, the baseline shifting is less obvious and hard to detect, which hinders the accurateT_g measurement at slow heating rate. On the contrary, fluorescent intensity doesn’t relate to measuring time. Consequently, the measuring sensitivities at different heating rates are the same for fluorescent method. Even at a slow heating of 3 ^oC can we obtain a clear T_g value for PMMA. For another thing, the same shape of fluorescent decay curves in Figure 13A-C can verify the good repeatability of ADEtect. 4. T_gmeasurements using different fluorescent molecules

According to the previous discussed proposed working mechanism, the AIEgens are perfect candidates as fluorescent probes for glass transition detection. Conventional aggregation-caused quenching (ACQ) dyes without rotors, however, should be less sensitive or not applicable for this application. Therefore, different fluorescent molecules, including AIE and ACQ molecules, are selected to verify the proposed working mechanism. The selected ACQ molecules (perylene) wascommercial available. Similar procedures for sample preparation, measurement and data processing have been done using AIE molecules (Silo-2OMe, TPA-BMO, DPA-IQ, TPATPE and BTPE- PI) and ACQ molecules (perylene) as fluorescent probes. As expected, all these three AIE molecules can be used to detect the T_g of PS, showing similar results(Figure 14A-E). So far, DPA-IQ is proved to be the best candidate, but the selection principle for higher sensitivity of AIEgens is not well established yet. On the other hand, the fluorescent decay curves of ACQ-doped polymer film didn’t show such turning point within the measurement temperature (Figure 14F). This is because conventional ACQ dyes usually possess disc-like planar structures without rotors. Thus the fluorescence of ACQ dye is not easily affected by the changes of free volume or segmental motions in polymer matrix. This comparison study has successfully verified the proposed mechanism for glass transition detection using ADEtect. 5. Prototype device developed for T_g measurements using AIE molecules as fluorescent probes

Based on fluorescent method described, we have designed and developed a device for glass transition detection of polymer materials using AIEgens as fluorescent probes. The prototype device is integrated with a program-controlled heating stage, an UV lamp and a camera detector, and is connected to a computer with auto-data processing software. The design principle is illustrated in Figure 2. Several advantages such as low cost, simple sample preparation, easy operation, high sensitivity, high accuracy and auto-data processing can be achieved. 6. Physical sensing of phase-separated morphology of polymer blends

6.1 Synthesis and characterization data of AIEgen of DNTPh

The synthetic route of DNTPh is provided in Scheme 1. The experimental procedure is as follows:Compound 1 and 2 were synthesized according to the literatures [E. Wang, E. Zhao, Y. Hong, J. W. Y. Lam, B. Z. Tang. J. Mater. Chem. B2014, 2, 2013−2019; R. L. Carlson, R. S. Drago. J. Am. Chem. Soc.1963, 85, 505−508].Under an atmosphere of N₂,n-BuLi (0.6 mL, 1.2 mmol, 2.0 M in hexane) was added dropwise to a solution of compound 1 (0.497 g, 1.0 mmol) in dry THF (20 mL) at–78 ^oC. After continuation of stirring for 2 h at–78 ^oC, compound 2 (0.232 g, 1.2 mmol) was slowly added to the mixture and continued stirring at the same temperature for 1 h. The mixture was allowed to warm to room temperature (22 °C), quenched with 10% aqueous HCl (10 mL), and stirred for 30 min. The aqueous phase was separated and washed with DCM (3 × 10 mL), dried over anhydrous MgSO₄, and evaporated in vacuo. The crude product was purified on a silica-gel column using n-hexane/ethyl acetate (3:1) as eluent giving DNTPh as a light yellow solid (0.397 g, 70%).

1H NMR (400 MHz, CDCl₃) δ(ppm) = 7.77 (d, J = 8.0 Hz, 2H), 7.52 (d, J = 8.0 Hz, 2H), 7.14–7.06 (m, 7H), 6.93–6.89 (m, 6H), 6.45 (dd, J = 8.0, 0.8 Hz,4H), 4.11 (q, J = 8.0 Hz, 2H), 2.90 (d, J = 4.0 Hz, 12H), 1.45 (t, J = 8.0 Hz, 3H); ¹³C NMR (100 MHz, CDCl₃) δ(ppm) = 195.50, 162.48, 149.94, 149.27, 149.13, 144.93, 143.16, 135.91, 134.98, 132.83, 132.76, 132.56, 131.77, 131.46, 130.55, 129.56, 127.90, 125.94, 124.14, 113.97, 111.48, 111.36, 63.84, 40.47, 14.85.HRMS (EI) m/z: [M⁺] calcd for C₃₉H₃₈N₂O₂, 566.2933; found, 566.2613. 6.2 Photo-physical properties of DNTPh

The maximum emission peak of DNTPh in solid state located at 530 nm (Figure 15). Figure 16depicts the change of emission intensity of DNTPh with the variation of water fraction (f_w) in THF/water mixtures. The result showed that when f_w was lower than 80%, the solution of DNTPh was basically non-emissive. When the water content was enhanced to 80% and 90%, the fluorescence intensity increased dramatically, suggesting a typical AIE property of DNTPh. After careful inspection of the trend, it is found that when f_w was changed from 0% to 20%, the emission of DNTPh was slightly decreased, which might be due to thetwisted intramolecular charge transfer (TICT) attribute. To verify this, we then investigate the optical properties of DNTPh in organic solvents with different polarities. As shown in Figure 17, DNTPh showed similar absorption spectra with absorption peaks (λ_ab) at 383−396 nm in different solvents. Although the change is small, λ_ab is generally blue-shifted as the solvent polarity increased (Table 4). By contrast, the emission spectra of DNTPh altered significantly in distinct solvent (Figure 18) and the data of emission maximum peaks (λ_em) was summarized in Table 4. Clearly, the λ_em red-shifted with the increment of solvent polarity. For example, from less polar solvent toluene to high polar solvent MeCN, the emission peak of DNTPh shifted from 500 to 588 nm. Such a solvatochromism phenomenon was further explored by the Lippert- Mataga equation (Figure 19).From the plots of Stokes shift–solvent polarity (Δƒ), we can find that the fitting line for DNTPh are positive with a slope of 7971. The results indicate that DNTPh possesses both AIE and TICT features. 6.3Preparation of polymer blend samples and experimental procedure

The phase-separated morphology of polymer blends can be affected by the polymer and solvent properties,substrate types, spin-coating rates, temperatures, blend ratios, etc. In general, higher polymer concentration, higher molecular weights (M_w), slowly evaporating solvent, and lower spin speeds will lead to bigger domain size [E Moons Revie]. Thus, to generate an obvious phase-separated structure, polymers with high molecular weights are selected and toluene is chose as the main solvent due to its relatively slow evaporation rate. General procedure for the preparationof polymer blend samples is illustrated in Figure 20. Toluene and CHCl₃ were used without further purification.PS (M_w = 280 000, T_g = ~100 ºC), PB (M_w = 200 000, T_g =−100 ºC), PMMA(M_w = 120 000, T_g = ~105 ºC) were dissolved in toluene, whereas PEG (M_w = 20 000, T_g = ~40 ºC) was dissolved in CHCl₃ due to their poor solubility in toluene. A typical procedure for the preparation of TPE doped thin filmof PS/PB = 50/50 (w/w)is given below as an example. 0.5 g PS and 0.5 g PB were dissolved in 10 mL toluene, respectively. Then 0.25 mL PS solution and 0.25 mL PB solution were mixed together, giving a PS/PB blend solution.AIEgen solution was prepared by dissolving 0.005 g TPE in 2 mL toluene. Afterward, 0.1 mL dye solution was mixed with the prepared 0.5 mL polymer blend, following by subsequent sonication for 1 h to generatea homogeneous solution composed of 42 mg/mLof polymer concentration and 1 wt% content of AIEgen. Uniform thin films wereobtained by spin-casting themixed toluene solution onto quartz plates(1 min, 1000 rounds per min), which was allowed to dry for 24 h under ambientconditions.The thin films were then imaged using an Olympus BX41 fluorescent microscope at the ultraviolet light excitation = 330−385 nm (dichroic mirror = 400 nm, and emission filter = 420 nm long pass).The fluorescence images were captured using a computer-controlled SPOT RT SE 18 Mono charge-coupled device (CCD) camera.   6.4Visualization of the morphologies of polymer blends by TPE and TPE2CN

PS is a verystiff and brittle material, whereasPB is rubbery and can absorb energy under stress. Immiscible blends of PS and PB are commercially available andknown as high-impact polystyrene. By blending PS with a small amount of PB, the modified PS is tougher, more ductile, and less likely to break upon bending. Due to the difference of T_gbetween PS and PB, it is promising to visualize the phase morphology of PS/PB blend using AIEgens.TPE is a well-studied and famous AIEgen, whichexhibits high fluorescent yield in solid state and can be easily synthesized by the one-step McMurry reaction of benzophenonein high yields.Therefore, we first applied 1 wt% TPE to stain PS/PB blend as a model system.

The uniform dispersion of TPE probes in the polymer matrix was confirmed by X- ray diffractometry (XRD) analysis, asno sharp diffraction peaks were observed in PS/TPE and PB/TPE films(Figure 21).From the emission spectra shown in Figure 22,the fluorescent intensityof the PS filmdoped with 1 wt% TPEis significantly higher than that of TPE/PB film with a maximum at about 460 nm,probably due to the RIM mechanism and better miscibility between PS and TPE. Based on this result, we then examined the phase morphology of the thin films of TPE doped PS, PB homopolymers and their blendwith the PB mass fraction (w_PB) of 50% using a fluorescent microscope. As depicted in Figure 23, the thin films of TPE/PS and TPE/PB showed smooth surface topography in both bright-field and fluorescent images.The fluorescent image of TPE/PS film exhibited anintense blue emission, whereas TPE/PB film was faintly emissive.Meanwhile, TPE/PS/PB film showed a well distinguishable phase-separated morphology.By comparison,the brightly emissive“isolated islands” in the fluorescent image can be assigned to be the PS-rich phase, which is surrounded by the continuous and weakly emissive PB-rich phase. The merged image of the corresponding bright-field image and fluorescent image clearly showed the morphology and spatial distribution of PS and PB phases in the blend film. The diameters of these separated PS domains is in the range of 7−18 μm.SEM experiment was conducted on the same polymer film at a specific region (Figure 24A). The SEM result is consistent with the phase morphology obtained from the fluorescent microscope, but the resolution and contrast between two phases is much lower and even hard to be detected.Although the phase separation between PS and PBis partially visible in the bright-field image(Figure 24B), it lacked the depth and the accuracy to identifythe polymer composition in the blend.All these shortcomings can be overcome by fluorescence imaging, which has facile sample preparation procedure, no film damage, high contrast and sufficient sensitivity to distinguish each component. Under excitation, the morphology of the polymer blend became clearly visible (Figure 24C).

To study the effect of dye concentration on the imaging, we also tested PS/PB systems with the TPE content of 0.1 wt% and 5.0 wt%. The results showed that neither increasing nor decreasing the probe concentration can give a better imaging result.As indicated by the XRD results shown in Figure 25A, 0.1 wt% TPE distributed uniformly in the polymer films.However, the PS and PB films doped with 0.1 wt% TPE showed a comparably weak emission in the fluorescent image (Figure 26). As a consequent, the contrast between two phases in PS/PB blend is much lower than that of the blend doped with 1.0 wt% TPE. On the other hand, when 5.0 wt%TPE is applied in polymer films, small crystal-like particlescan be observed even by naked eyes due to the relatively poor miscibility of TPE in PB matrix. The uneven distribution of 5.0 wt% TPE in PB film was also supported by the detected diffraction peaks from TPE in the thin film (Figure 25B).Thus, 1.0 wt% was chosen to be the suitable concentration for the following investigation.

Encouraged by the preliminary result, the phase-separated structures in thin films of PS/PB blends with different blend ratios were then systematically imaged and investigated using this fluorescent method.As displayed in Figure27, blend ratio has a strong effect on the phase-separated morphology and domain size.In the thin film of PS/PB blend with w_PB of 10%, faintly emissive PB domains dispersed uniformly in a brightly emissive PS matrix. PS is the major component, and PBseparates from PS phase into small and round-shaped domains. Asw_PB increases, the isolated PB spheres tend to coalescetogether, resulting inanobvious increase of PB domain size and irregular domain shapes. A bicontinuous interpenetrating networks appears when w_PBreaches 30%. Further increment of w_PB to 40% leads to a reversed morphology, and PS becomes a minor component. The irregularly-shaped and blue emissive PS phase is embedded within a dark PB matrix.For w_PB= 50%, the PSdomains change to spherical morphology.With the gradual increase of PB fraction in the immiscible blend, the average size of the island- like PS domainsgets much smaller and finally becomes even negligible (below the detection limit of the optical microscope) when w_PB= 90%.

Similar to the blue emissive TPE, AIEgen TPE2CN can also serve as a fluorescent probe to detect the morphology of PS/PB blend by intensity difference. As shown in Figure 28, the emission intensity of TPE2CN in PS matrix is almost double higher than that in PB.The associated photos suggest that the thin film of TPE2CN/PS emits a much stronger yellowish-green light than TPE2CN/PB. The bright-field and fluorescent images of the thin films of TPE2CN doped homopolymers exhibit a uniform phase morphology (Figure 29), andthe images of PS/PB blend with w_PB of 50% show obvious phase- separated structure. As indicated by the fluorescent image, the brightly emissive and circularPS domains dispersed evenly in a weakly emissive PB matrix. The diameter of these PS spheres is in the range of 2−8 μm. 6.5 Visualization of the morphologies of polymer blends by TPAMPO and DNTPh TPAMPO is areported triphenylamine (TPA)-based AIEgen with donor-π-acceptor structure[Y. L. Zhang, M. J. Jiang, G. C. Han, K. Zhao, B. Z. Tang, K. S. Wong, J. Phys. Chem. C2015, 119, 27630−27638]. Its light emission is strongly dependent on solvents, showing a solvatochromic property. In general, as the solvent polarity increases, the emission wavelength of TPAMPO would red-shift accordingly. For example, from hexane, toluene to THF, its emission color gradually change from blue (λ_em = 457, 482 nm), green (λ_em = 509 nm) to orange (λ_em = 576 nm). Such a solvatochromism phenomenon can be attributed to and theTICT property of TPAMPO.Herein, we utilized its TICT feature to identify polymer componentsby different emission color in a polymer blend and thus achieve the detection of phase-separated morphology. Polymers with different structural polarity, includingPB, PS, PMMA and PEG, were selected and the photoluminescent behavior of TPAMPO in the thin films of these homopolymers was first investigated. As shown in Figure 30, the maximum emission wavelength of TPAMPO/PB, TPAMPO/PS, TPAMPO/PMMA, and TPAMPO/PEG thin films located at 499, 512, 525, and 567 nm, and exhibitedblue, green, and orange emission color, respectively.The morphology of polymer blend PS/PB, PMMA/PB, and PEG/PB were then studied by fluorescent microscopy using TPAMPO as the staining agent. Compared with TPE and TPE2CN, in this case, the PS and PB phase in the blend is identified by the difference in emission color, which is more reliable and suffers less from the inherent roughness of the film itself. In the fluorescent image of TPAMPO/PS/PB, the green emissive and circular domains can be attributed to the PS phase, and the blue emissive matrix is the PB phase (Figure 31). Similar phenomenon was also observed in TPAMPO/PMMA/PB system, where irregular PMMA domain with green emission is surrounded by continuous and blue emissive PB matrix (Figure 32). For PEG/PB blend with w_PB of 50%, high-contrast and well-resolved morphology structure was observed, which is quite different from PS/PB blend. The orange emissive and irregular-shaped domain is embedded in a continuous phase with blue emission(Figure 33). Through comparison with the fluorescent image of TPAMPO/PEG and TPAMPO/PB, we can readily assign the orange emissive domains as PEG-rich phase, while the blue background is PB-rich phase.

The above-mentioned DNTPh is also an AIEgen with characteristic TICT feature. As suggested by Figure 34, it emits blue light at 510 nm when doped in PB matrix, but shows green emission at about 530 nm in PMMA and PS homopolymers. Similar to TPAMPO, DNTPh canalso be used as an effective fluorescent probe to visualize the domain morphology of PS/PB and PMMA/PB blend based on the emission color difference (Figure 35). In addition, the result of DNTPh/PMMA/PB system (Figure 36) further demonstrated the advantage of this fluorescent method over traditional optical microscopy. In Figure 36C, the bright-field image with relatively small magnification time showed a chaotic topography, while the magnified image suggested a homogeneous composition. On the other hand, the corresponding fluorescent image gained a much clearer and more detailed insight into the microscopic morphology of PMMA/PB without the interference of misleading holes from the film roughness.The micro-morphologies, which cannot be seen in the bright field, become visible after excitation. 7. Chemical sensing using an axially chiral boron-based AIEgen: (R)-JR-5

7.1Synthesis of (R)-JR-5 Commercially available 2-bromobenzophenone (JR-1) was treated under Suzuki- Miyaura conditions to give JR-2 in good yields (Scheme 2). Boric ester JR-2 was converted into its corresponding trifluoroborate JR-3 by treatment of a methanolic solution of KHF₂. In order to obtain the free boronic acid JR-4, trifluoroborate JR-3 was hydrolyzed with lithium hydroxide. Subsequently, boronic acid JR-4 was converted into (R)-JR-5 via a two-step, one-pot sequence, involving the formation of an intermediate hydrazone from 1-methyl-1-phenylhydrazine. A test experiment using the same conditions in deuterated chloroform has previously shown completion of the hydrazone formation in less than 30 min. By the subsequent addition of (R)-BINOL and heating for two days at 70 °C in a sealed pressure tube, the target compound (R)-JR-5 was furnished in 56% yield over four steps as a 2:1 diastereoisomeric mixture as a result from a hindered rotation around the N–N-bond. The ORTEP plot of (R)-JR-5 is shown in Figure 37, proving unambiguously the proposed structure of (R)-JR-5. Only one diastereoisomer was observed in the X-ray crystal structure. The molecular structure exhibits two noteworthy features: first, the axial chirality of the BINOL-moiety (θ_{(C21–C22– C32–C31)} = 49.6°) is transferred to the 1-methy-1-phenylhydrazone substituent (θ_{(C1–N1–N2– C11)} = 81.4°) and even further to the pendant phenyl ring on C1 (θ_{(C2–C1–C41–C42)} = 51.6°). Second, the boron-nitrogen bond-length d_(B1–N1) amounts to 1.66 Å and hence constitutes an elongation compared to those lengths commonly observed between two second-period elements. Thus, the bond is weakened and potentially liable to breakage in the presence of a competing Lewis-base.

Experimental details

Phenyl[2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl]methanone (JR-2): A degassed (N₂, 30 min) solution of 2-bromobenzophenone (JR-1) (5.15 g, 19.7 mmol), bis(pinacolato)diboron (6 g, 23.7 mmol), and KOAc (5.7 g, 58 mmol) in dry THF (125 mL) was treated with [Pd(dppf)Cl₂] (721 mg, 0.99 mmol) and heated at 65 °C for 18 h. The mixture was diluted with Et₂O (200 mL), washed with water (3x 50 mL), brine (1x 50 mL), dried over anhydrous MgSO₄, and evaporated in vacuo to give an oily residue. Column chromatography (SiO₂; hexane/EtOAc 95:5) afforded the pure compound as a white solid (5.1 g, 84%). R_f = 0.70 (SiO₂; nhexane/EtOAc 8:2); analytical data conform with those reported previously[K. L. Billingsley, T. E. Barder, S. L. Buchwald, Angew. Chem. Int. Ed.2007, 46, 5359–5363].

Potassium benzophenone-2-yltrifluoroborate (JR-3): A stirred solution of JR-2 (900 mg, 2.9 mmol) in a MeOH/THF (1:1, 20 mL) was treated with an aqueous KHF₂ solution (4.5 m, 4 mL, 16.4 mmol) at 22 °C for 15 min resulting in a cloudy mixture, which was subsequently concentrated in vacuo. The residue was dissolved in hot acetone, filtered, and evaporated in vacuo affording crude JR-3. Subsequent recrystallization from acetone/Et₂O gave colorless crystals (769 mg, 92%).

1H NMR (400 MHz, acetone-d₆) δ = 7.82–7.70 (m, 3H), 7.57 (dd, J = 6.8, 1.5 Hz, 1H), 7.48–7.39 (m, 2H), 7.32 (dd, J = 7.0, 1.5 Hz, 1H), 7.20 (dd, J = 7.0, 1.5 Hz, 1H), 7.06–7.00 ppm (m, 1H); ¹³C NMR (101 MHz, acetone-d₆) δ = 202.05, 143.00, 138.52, 133.25, 132.32, 130.25, 127.88, 125.61, 124.69 ppm; ¹¹B NMR (128 MHz, acetone-d₆) δ = 3.31 ppm (br. q); ¹⁹F NMR (376 MHz, acetone-d₆) δ = 138.48 ppm (br. d).

Benzophenon-2-ylboronic acid (JR-4): A solution of JR-3 (374 mg, 1.3 mmol) in acetonitrile/water (2:1, 15 mL) was treated with LiOH•H₂O (191 mg, 4.5 mmol) and stirred for 24 h at 22 °C. The mixture was acidified with conc. aqueous NH₄Cl (8 mL) and hydrochloric acid (1 m, 2 mL), extracted with EtOAc (3x 10 mL), dried over anhydrous MgSO₄, and evaporated in vacuo to afford boronic acid JR-4 as a white solid (293 mg, 100%).

1H NMR (400 MHz, acetone-d₆) δ = 7.80–7.68 (m, 3H), 7.63 (t, J = 6.8 Hz, 1H), 7.61–7.55 (m, 2H), 7.55–7.47 (m, 3H), 2.83 ppm (s, 2H); ¹³C NMR (101 MHz, acetone- d₆) δ = 196.56, 143.85, 137.67, 133.22, 131.91, 129.30, 129.25, 129.07, 127.72, 127.67 ppm; ¹¹B NMR (128 MHz, acetone-d₆) δ = 31.10 ppm (br.).

(R)-2-{[2-(dinaphtho[2,1-d:1',2'-f][1,3,2]dioxaborepin-4- yl)phenyl](phenyl)methylene}-1-methyl-1-phenylhydrazine ((R)-JR-5; 2:1 diastereoisomeric mixture): A pressure tube was charged with boronic acid JR-4 (194 mg, 0.86 mmol) anhydrous MgSO₄ (500 mg, 4.2 mmol), CHCl₃ (5 mL), and 1-methyl-1- phenyl-hydrazine (100 μL, 0.86 mmol). After stirring this mixture for 30 min at 22 °C, (R)-BINOL (246 mg, 0.86 mmol) was added and the mixture heated to 70 °C for 2 d. The mixture was filtered, the filtrate evaporated in vacuo, and filtered again over alumina (10   g) with n-hexane (20 mL) and Et₂O to give a 2:1 diastereoisomeric mixture of (R)-JR-5 as an orange-red powder (364 mg, 73%).

1H NMR (400 MHz, CDCl₃) δ = 7.98 (d, J = 8.5 Hz, 2H), 7.88 (d, J = 8.5 Hz, 2H), 7.81–7.62 (m, 2H), 7.60–7.41 (m, 5H), 7.41–7.33 (m, 5H), 7.33–7.27 (m, 4H), 7.18–7.12 (m, 3H), 6.88 (d, J = 8.5 Hz, 2H), 3.37 and 3.31 ppm (s, 3H); ¹¹B NMR (128 MHz, CDCl₃) δ = 11.09 ppm (br.); HRMS (MALDI): calcd. for C₄₀H₂₉BN₂O₂ [M]⁺ 580.2322; found 580.2309 (94%); calcd. for C₅₇H₄₈BN₄O₂ [M+DCTB+H]⁺ 831.3870; found 832.3398 (100%). 7.2 Photo-physical properties

Figure 38A illustrates the UV-vis spectra of (R)-JR-5 in 1,2-dichloroethane (DCE; solid trace) as well as in THF (dashed trace). The CD spectrum shown in Figure 38B demonstrates the strong circular dichroism in the lower wavelength region. Below 300 nm, a bathochromic shift of about 20 nm was observed for the DCE-solution compared to the spectrum recorded in THF, whereas the band at 333 nm did not undergo a shift within the margin of error. Interestingly, a broad band with a maximum at 365 nm extending into the blue-green region above 500 nm observed when measured in DCE, was absent in THF solution. This effect was also observed by the naked eye: (R)-JR-5 solutions in solvents that have Lewis-basic groups (alcohols, ethers, ketones, etc.) were yellow as opposed to those in non-coordinating solvents (hydrocarbons, chlorinated solvents), which featured an intense red color similar to the material in solid state. Considering the data obtained from the X-ray crystal analysis, a competitive coordination of Lewis-basic solvents to the boron is very likely to occur resulting in B–N bond cleavage (Scheme 3). Such competitive binding would alternate the chromophore leading to a hypsochromic shift and disappearance of the broad band at 365 nm. DFT calculations at the B3LYP/6- 31G(d) level revealed that the HOMO at–4.96 eV is mainly located at the BINOL- moiety, whereas the LUMO at–2.28 eV is located at the borepin-heterocycle and its pendant aryl groups (Figure 39). Interestingly, the LUMO significantly stretches along the C3–B1–N1 bonds in a π−fashion. That might explain the dramatic blue shift upon breaking the B1–N1 bond as a result of bond-formation to B1. Such blue-shift was also reflected in the photoluminescence(PL) spectra. To investigate the AIE-behavior, the fluorescence of a series of (R)-JR-5 in THF/c-hexanol (10 μM) with different volumetric fractions (100:0 to 0:100) was recorded (Figure 40). Due to the fact that (R)-JR-5 slowly hydrolyzes in the presence of water, the application of the standardly used system THF/water was not an option. In addition, DCE/n-hexane did not prove as a viable solvent system either, since the solubility in hexane is too high to form aggregates at low concentrations that are required for these measurements. Thus, the difference in viscosity between THF and c-hexanol was exploited to enforce an attenuation of intramolecular motions. Since both, THF (0.46 cP) and c-hexanol (57.5 cP),[viscosity @ 25 °C (298.15 K): CRC Handbook of Chemistry and Physics, 85th Edition, David R. Lide, ed., CRC Press, Boca Raton, FL, 2004. cP is the abbreviation for centipoise, a standard unit of measurement for viscosity.] coordinate to the boron atom leading to disappearance of the long-wavelength transition, an excitation wavelength of 360 nm was chosen. Two emission bands at 406 and 442 nm were observed. While the band at 406 nm showed aggregation-induced enhancement (AEE) behavior, the emission at 442 nm displayed typical AIE behavior.

In order to investigate the emission properties for (R)-JR-5 in a non-coordinated state, a film in a PS matrix with a weight-fraction of 10% was prepared. At an excitation wavelength of 480 nm, a fluorescence maximum at 615 nm was observed (Figure 41). 7.3 Staining polymer blends using (R)-JR-5

(R)-JR-5 is a promising reagent to chemically staining polymer blends, due to its abilityto dynamically and reversibly coordinate to Lewis bases accompanied by fluorescence quenching. Only the PS phases remained red-fluorescent in various PS- based mixtures. For analyzing these mixtures, the polymersolutions in toluene were mixed and doped with (R)-JR-5 (2%). The polymer samples(PS: M_w = 280 000, T_g = ~100 ºC; PEG: M_w = 3 600, T_g = ~60 ºC; PLA: M_w = 60 000, T_g = ~60 ºC) were dissolved in toluene to give a 5 wt%solution. Subsequently, the polymer solutions were mixed witha solution of (R)-JR-5 (0.01 M) to give blends in the desiredcomposition with 2 wt% content of (R)-JR-5. The resulting solutions (300 m L)was subsequently spin- coated (1 min, 800 rounds per min) onto glasssubstrates, which was allowed to dry for 24 h under ambientconditions.Two selected examples (Figures 42 and 43) show both the bright-field image as well as the red fluorescence that originates from non-coordinated (R)-JR-5 in the PS phase. In both cases, a much more detailed insight into the microscopic morphology is obtained when observed after electronically exciting the samples. In fact, micro-morphologies become visible after excitation, which cannot be seen in the bright field. Hence, (R)-JR-5 allows for a facile analysis of polymer blends by purely optical measurements. 7.4Enantioselective sensing of(R)-JR-5

Since (R)-JR-5 is a Lewis acid with a binding site adjacent to the axially chiral BINOL-substituent, we investigated weather two enantiomeric alcohols would bind with different binding constants depending on their chirality. For its relevance and avaialability, (+)- and (–)-menthol were tested. As above-mentioned, the coordination of a Lewis base to the boron atom leads to a quenching of the broad absorption band at λ_max = 365 nm. Hence, UV-vis spectra at different menthol concentrations, ranging from 0 to 0.8 mM, were recorded and the data analyzed through a Stern-Volmer-Plot (Figure 44) by plotting the respective intensities at 400 nm. While the naturally occuring (–)-menthol only showed a binding constant of 4×10^–5 M^–1, the artificial (+)-enantiomer exhibited a 150- fold increased binding (K = 0.0061 M^–1). This finding was also reflected in a qualitative way when PS-films (10% (R)-JR-5) were treated with solutions of the respective menthol enantiomers (Figure 45).

Claims

  CLAIMS  With the information contained herein, various departures from precise descriptions of the present subject matter will be readily apparent to those skilled in the art to which the present subject matter pertains, without departing from the spirit and the scope of the below claims. The present subject matter is not considered limited in scope to the procedures, properties, or components defined, since the preferred embodiments and other descriptions are intended only to be illustrative of particular aspects of the presently provided subject matter. Indeed, various modifications of the described modes for carrying out the present subject matter which are obvious to those skilled in chemistry or related fields are intended to be within the scope of the following claims. We claim:

1. A method of measuring glassing transition temperatureof polymeric materials, by recording fluorescent images of AIEgens doped polymer materialsin an array at different temperatures and utilizing grayscale of fluorescent images at different temperatures to identify the T_g of measured polymers.

2. The emission color of AIEgens in claim 1 can be from blue to red, covering all the visible colors.

3. The AIEgens in claim 1 can be chemical structures consisting of:

Where R, R’, R’’, R’’’, R’’’’ and R’’’’’is  independently selected  from  the group comprising of H,  alkyl,  unsaturatedalkyl,  heteroalkyl,  cycloalkyl,  heterocycloalkyl,  aryl,  and  heteroaryl,  C_nH_2n+1,C₁₀H₇,  C₁₂H₉,  OC₆H₅,  OC₁₀H₇  and  OC₁₂H₉,  C_nH_2nCOOH,  C_nH_2nNCS,  C_nH_2nN₃,C_nH_2nNH₂,  C_nH_2nSH, C_nH_2nCl, C_nH_2nBr, C_nH_2nI, N(C_nH_m)₂, SC_nH_m. 

4. The AIEgens in claim 1or 2 or 3 can be chemical structures consisting of:

wherein R is from the group consisting of:

n = 0~20, R’ and R’’ is independently selected from:H, alkyl, unsaturatedalkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl, C_nH_2n+1,C₁₀H₇, C₁₂H₉, OC₆H₅, OC₁₀H₇ and OC₁₂H₉, C_nH_2nCOOH, C_nH_2nNCS, C_nH_2nN₃,C_nH_2nNH₂, C_nH_2nSH, C_nH_2nCl, C_nH_2nBr, C_nH_2nI, N(C_nH_m)₂, SC_nH_m.

5. A luminogen in claim 4, wherein the structures are selected from the group consisting of:

6. The AIEgens in claim 1 or 2 or 3 can also be chemical structures consisting of:

wherein R is from the group consisting of

7. A luminogen in claim 6, wherein the structures are selected from the group consisting of

8. The AIEgens in claim 1 or 2 or 3 can be chemical structures consisting of:

wherein R, R’, R’’, R’’’ and R’’’’ is independently selected from the group consisting of H, alkyl, unsaturated alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl.

9. A luminogen in claim 8, wherein the structures are selected from the group consisting of:

10. The AIEgens in claim 1 or 2 or 3 can be chemical structures consisting of:

wherein R, R’, R’’ and R’’’ is from the group consisting of H,

11. A luminogen in claim 10, wherein the structures are selected from the group consisting of:

12. The AIEgens in claim 1 or 2 or 3 can also be chemical structures consisting of:

wherein each R, R’ and R’’ is independently selected from the group consisting of H, alkyl, unsaturated alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl.

13. A luminogen in claim 12, wherein the structures are selected from the group consisting of:

14. The polymeric materialsin claim 1 can be amorphous polymers.

15. The polymeric materials in claim 1 can be semi-crystalline polymers.

16. The polymeric materials in claim 1 can be crystalline polymers.

17. The polymeric materials in claim 1 can be polystyrene, polymethylmethacrylate, polyvinylchloride,poly(styrene-butadiene-styrene).

18. The AIEgen-doped polymer materials in claim 1 can be in the state of film, powders and bulky materials.

19. The array in claim 1 can be comprised of at least 1 material.

20. The array in claim 1 can be comprised of at least 10 material.

21. The array in claim 1 can be comprised of at least 100 material.

22. A method of identifying polymer composition in a polymer blend:

Comparing the photoluminescent property, including the emission brightness or emission color of AIEgens, in each domain with that in the associated homopolymers.

23. The AIEgens in claim 22 can be chemical structures consisting of:

 

Where R, R’, R’’, R’’’, R’’’’ and R’’’’’  is  independently selected  from the group comprising of H,  alkyl,  unsaturatedalkyl,  heteroalkyl,  cycloalkyl,  heterocycloalkyl,  aryl,  and  heteroaryl,  C_nH_2n+1,C₁₀H₇,  C₁₂H₉,  OC₆H₅,  OC₁₀H₇  and  OC₁₂H₉,  C_nH_2nCOOH,  C_nH_2nNCS,  C_nH_2nN₃,C_nH_2nNH₂,  C_nH_2nSH, C_nH_2nCl, C_nH_2nBr, C_nH_2nI, N(C_nH_m)₂, SC_nH_m. 

24. The AIEgens in claim 22 or 23 can be chemical structures consisting of:

wherein each R is independently selected from the group consisting of H, alkyl, unsaturated alkyl, heteroalkyl, cycloalkyl, heterocycloalkyl, aryl, and heteroaryl.

25. A luminogen in claim 24, wherein the structures are selected from the group consisting of

26. The luminogens of in claim 22 or 23, including TPE and TPE2CN,wherein the luminogens can be used as fluorescent probes to distinguish the polymer components in an immiscible polymer blend by the emission intensity difference based on RIR mechanism.

27. The luminogens in claim 24, wherein the structures are selected from the group consisting of

28. The synthetic method of DNTPh in claim 27, comprising of the synthetic procedures and the corresponding characterization data.

29. The luminogen in claim 27, wherein the luminogen can be used as a fluorescent probe to distinguish the polymer components in an immiscible polymer blend by the emission color difference based on RIR and TICT mechanism.

30. The AIEgens in claim 22 or 23 can also be chemical structures consisting of:

wherein R is from the rou consistin of

31. A luminogen in claim 30, wherein the structures are selected from the group consisting of

32. The luminogen in claim 31, wherein the luminogencan be used as a fluorescent probe to distinguish the polymer components in an immiscible polymer blend by the emission color difference based on RIR and TICT mechanism.

33. An axially chiral boron-based AIE en with red emission：

34. The methods of preparation of (R)-JR-5 in claim 33, comprising of the synthetic procedures and corresponding characterization data of the intermediates and the final product.

35. The luminogen of (R)-JR-5 in claim 33, which can distinguish the morphologies of polymer blends that were composed of a non-coordinating and a Lewis-basic or hetero-atom containing polymer based on a selectively chemical sensing mechanism.

36. A method of sample preparation and imaging in claim26, or 29, or 32, or 35comprising:

Doping the AIE-active probes in claim 22 or 23 to a homopolymer or polymer blend; anddetecting phase morphologies by fluorescent microscopy and obtaining bright- field and fluorescent images.

37. The luminogen of (R)-JR-5 in claim 33, wherein the luminogen can be used in Enantioselective sensing.

38. A method of identifying polymer composition in a polymer blend:

Comparing the photoluminescent property, including the emission brightness or emission color of AIEgens, in each domain with that in the associated homopolymers.