N-isopropylacrylamide Gel Research Articles

Feasibility evaluation of N-Isopropyl Acrylamide 3D gel dosimeters for proton therapy.

This study aimed to investigate the feasibility of applying 3D gel dosimeters for proton therapy. Two different formulations (5-5-3-5, 5-3-3-10) for the N-Isopropyl Acrylamide (NIPAM) polymer gel were used to find the best composition for the application of NIPAM polymer gels for proton therapy. The reaction of the gel under different physical conditions, including dependence on energy and dependence on the dose rate of the NIPAM gel under proton irradiation, was also explored. A NIPAM gel dosimeter was used to record the 3D dose distribution, and a self-developed parallel beam optical computed tomography scanner was used to obtain non-irradiated and post-irradiated gel phantom images. The NIPAM gel was filled into a cylindrical acrylic phantom. The results showed that the optical density of the irradiated NIPAM dosimeter was linear in the dose range of 0 to 6 Gy, and the linearity of the two NIPAM gel formulations at the depth of the dose point (2 cm) was 0.98 to 0.89. The dose depth curves showed different patterns with different gel sensitivities. This study demonstrated that the NIPAM gel dosimeter with the 5-3-3-10 formulation is suitable for verifying the dosimetry dose of proton beams.

Applying the N-isopropylacrylamide gel dosimeter to quantify dynamic dose effects: A feasibility study.

BACKGROUND: The gel dosimeter is a chemical as well as a relative dosimeter.OBJECTIVE: To evaluate the feasibility of using N-isopropylacrylamide (NIPAM) gel dosimeter to observe the dynamic dose effects and quantification of the respiration, and to help determine the safety margins.METHODS: The NIPAM gel dosimeter combined with the dynamic phantom was used to simulate radiotherapy of lung or upper abdominal tumor. The field set to 4 5 cm, simulate respiratory rate of 4 sec/cycle, and motion range 2 cm. MRI was used for reading, and MATLAB was used for analysis. The 3%/3 mm gamma passing rate 95% was used as a clinical basis for evaluation.RESULTS: The dynamic dose curve was compared with 4 5, 4 4, 4 3 cm TPS, and gamma passing rates were 74.32%, 54.83%, 30.18%. Gamma mapping demonstrated that the highest dose region was similar to the result of the 4 4 cm TPS. After appropriate selection and comparing that the 60% part of the dose curve with TPS, the gamma passing rate was 96.49%.CONCLUSIONS: Using the NIPAM gel dosimeter with dynamic phantom to simulate organ motion during respiration for dynamic dose measurement and quantified the dynamic dose effect is feasible. The results are consistent with clinical evaluation standards.

Properties of Zwitterionic Sulfobetaine Gels Containing Different Numbers of Methylene Units

The present research was performed aiming to develop gel with the characteristic of reversible thermosensitive in adsorbing heavy metal ions from its solution. There were three gels used in this study to adsorb heavy metal ion from salt solution provided Zn(NO3)2; copolymer gel consisting of zwitterionic betaine N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS), N,N-dimethyl(acrylamidopropyl)ammonium butane sulfonate (DMAABS), and DMAAPS copolymerized with thermosensitive N-isopropylacrylamide (NIPAM) gels. The aforementioned gels were employed to examine its ability in adsorbing and swelling after being synthesized through free radical polymerization before being affected by methylene spacer number, copolymerization, and temperature given. This research found that as the temperature increases, the ability of the gel in adsorbing the ions decreases. In the case of DMAAPS and DMAABS gel, the swelling degree value increases when the temperature also increases. Meanwhile, sulfobetaine which has larger spacer has higher adsorption ability but not with its swelling degree. In spite of having more spacer than DMAAPS, DMAABS found to have the smallest swelling degree value. In addition, NIPAM-co-DMAAPS was found to have both the highest adsorption ability and swelling degree value. Even though copolymer has less amount of sulfobetaine than DMAAPS and DMAABS gels’, the copolymer gel was found to have higher ability of adsorption as many as ten times of other gels.

Contraction waves in self-oscillating polymer gels

As one type of active soft matter, polymer gels coupled mechanical and chemical oscillations, such as Belousov–Zhabotinsky (BZ) gels are widely researched and developed into biomimetic actuators. In the previous literature, the self-oscillating BZ cylindrical gels can generate swelling waves along their longitudinal direction when they are operated without external stimuli. Here, we explore the contraction waves of BZ gels by the means of changing the external mechanical boundary. We firstly synthesize the self-oscillating gel, which is composed of N-isopropyl acrylamide (NIPAAm) gel and a covalently bound metal catalyst of the ruthenium complex. Then, the stress-curve of the gels is investigated to evaluate the elastic modulus of each state of the BZ gel and verified our method. Finally, we investigate the effects of several factors including initial diameters of the gel, various strain, and measuring process on the generation of contraction waves in gels undergoing the BZ reaction by experiments.

Behaviors of 3D-printed objects made of thermo-responsive hydrogels: motion in flow and molecule release ability

Functional and intelligent soft materials are useful for controlled release of medicines and other molecules. Poly(N-isopropylacrylamide) (PNIPAm) gels are well known as thermo-responsive gels with large discontinuous volume change which is commonly called as the volume phase transition. PNIPAm gels are expected to be applied to controlled-releasable material for drug delivery systems. Furthermore, we can fabricate arbitrary shapes made of gels freely by using 3D hydrogel printing techniques. Here we report that the effect of capsule shapes on behaviors of the PNIPAm objects under water flow with Reynolds number 102. In addition, we compared the behaviors of 3D-printed PNIPAm gel objects with 3D-printed polylactic acid (PLA) objects. The velocity at the first period of 2 or 3 s from the beginning of movement is slower than that of second period in the case of PNIPAm objects with ellipsoidal and bullet shapes. In other words, the capsules are accelerated after the period of 2 or 3 s. For the bullet shape objects, the velocity of the PNIPAm gel is approximately three times faster than that of PLA. It is considered that the cause of the difference between the velocities of PLA and PNIPAm gel is the difference of their frictions. The hydrogels possess commonly low friction properties. Finally, it is demonstrated that the 3D-printed PNIPAm capsules can release the solution inside the capsules by shrinking the PNIPAm gels, caused by volume phase transition.

Investigation of Gel Properties of Novel Cryo-Clay-Silica Polymer Networks.

Several methods to increase the mechanical and swelling properties of Poly(N-isopropylacrylamide) gels are known. In this study different methods were combined to systematically alter the gel properties. The combination of nanocomposite and cryo gels as well as silica post modification was used to modulate the gel strength. This new cryo-clay-silica gel based on N-isopropylacrylamide was investigated in respect to degree of swelling, kinetic of thermo responsive behavior and tensile strength. Here, the properties of new cryo-clay-silica gel were compared with properties of clay-, silica-clay and cryo-clay gels.

Technical Note: Radiotherapy dose characterization of gel dosimetry using shear wave elasticity imaging.

Radiotherapy is an effective treatment for many types of cancer in clinical settings. Gel dosimetry has the potential to record three-dimensional (3D) dose distribution compared to a conventional ion chamber. As the elasticity of the gel is altered after irradiation due to gel polymerization, we aim to measure the dose recorded in gel dosimetry with ultrasonic shear wave elasticity imaging (SWEI), a nondestructive and quantitative elasticity imaging tool. In this study, a cylindrical N-isopropylacrylamide (NIPAM) polymer gel with a diameter of 10cm and a height of 10cm and with cellulose as an ultrasonic scatterer was irradiated by a linear accelerator with the irradiation parameters of 6MV x-ray, dose rate of 100cGy/min and field size of 10 20mm2 . The six gel phantoms were irradiated with the dose of 0, 1, 3, 5, 8, or 10Gy. The gel phantoms were measured with SWEI at 24, 36, and 48h after x-ray irradiation. The two-dimensional (2D) shear wave velocity and Young's modulus maps corresponding to x-ray dose distribution were reconstructed following a time-of-flight reconstruction from a set of time-series displacement maps. The spatial resolution of the reconstructed SWEI image is ~1mm. Our results show that the elastic modulus increases linearly as irradiation dose increases (R2 =0.94 at 24h, R2 =0.98 at 36h, R2 =0.98 at 48h), suggesting that the gel elasticity is highly associated with x-ray irradiation dose at 36h post irradiation, and the dose resolution was 0.66kPa/Gy. From the 3D elastic modulus maps, the dose distribution along the depth and lateral direction can be reflected in the NIPAM gel dosimetry using SWEI as well. In this study, the irradiated NIPAM gel phantom was quantitatively measured with SWEI for the first time to read the dose distribution recorded in the gel dosimetry. The results suggest that the gel elasticity is highly associated with x-ray irradiation dose. In the future, 2D/or 3D dose distribution from intensity modulated radiotherapy (IMRT) or other potential particle radiotherapy will be measured and reconstructed with SWEI and compared with the dose map from a treatment planning system (TPS) in the clinic.

Selective separation of Cd(II) and Am(III) by coating pH-responsive hydrophilic gel on silica particles

ABSTRACT An N-isopropylacrylamide(NIPA) gel can swell and shrink in response to temperature and pH, and metal ion adsorption using NIPA gel containing N,N,N’,N’-tetrakis(2-methylpyridyl)ethylenediamine(TPEN) derivatives also follows this behavior. Here, we prepare novel TPEN-type-NIPA gel-coated porous silica particles with high TPEN content. The particles are highly effective in selective separation; they exhibit high selectivity to Cd(II) at pH 2, at low temperature. The novel TPEN-type-NIPA gel-coated porous silica particles exhibit a high Am(III)/Eu(III) separation factor of ~14 at pH 4, at which the selectivity to Am(III) is high. Hence, these particles will aid in the extraction of Am(III).

Collapse–Decollapse of Thermosensitive Polyelectrolyte Gels in Aqueous Media

The effect of temperature on water sorption by gels based on the copolymers of N-isopropylacrylamide with sodium p-styrene sulfonate containing 1, 3, and 5 mol % of charged monomer units is studied in aqueous media in the presence of salt (NaCl, KCl) or urea. It is shown that the incubation of gels in salt solutions leads to compression of the gels. With increasing temperature, the collapse of gels is observed in all studied media. The difference in the gel collapse temperature in water and salt solution increases with an increase in the fraction of charged units in the polymer gel network and in the salt concentration in the solution. With a return temperature decrease and gel decollapse, the mass of all gels in salt solutions (0.5–5.0 wt %) is completely restored. The incubation of gels in aqueous solutions of urea (0.5–5.0 wt %) has practically no effect on water sorption by gels before the collapse and the collapse temperature. However, the degree of swelling of polyelectrolyte gels during decollapse caused by a temperature decrease is much lower than the initial value, in contrast to the completely reversible swelling of the poly(N-isopropylacrylamide) gel under similar conditions.

Improvement of sensitivity of X-ray CT reading method for polymer gel in radiation therapy.

Three dimensional (3D) dosimetry methods are useful for advanced radiotherapy techniques such as stereotactic radiosurgery (SRS) and high dose rate (HDR) brachytherapy. Polymer gel is one of the more reliable 3D dosimetry techniques. More studies are needed to improve the efficiency of polymer gels for their application in dosimetry. In the current study, the best protocol for reading of N-isopropyl acrylamide (NIPAM) polymer gel by X-ray computed tomography (CT) was implemented for application in radiotherapy. The NIPAM gel was made and irradiated by 6MV. Its reading was done by the X-ray CT after 24h and the information examined by using the MATLAB software. In the present work, the different effects of slice thicknesses and voltages were investigated for its lower toxicity of NIPAM polymer gel. The results of a recipe of different filtering on the response curve of polymer gel was investigated. The measured dose sensitivity was =0.29±0.01 for the NIPAM dosimeter. The best sensitivity was achieved for 120kVp and the slice thickness of 10mm. The greater slice thickness gained more desirable sensitivity. This process was repeated by using different filtering with different thicknesses to obtain the best sensitivity. The sensitivity of X-ray CT reading technique of NIPAM Polymer gel depended on the slice thickness and kVp. The wiener2 filtering was useful to improving sensitivity.

A study of dose verification and comparison for complex irradiation field with high dose rate radiation by using a 3D N-isopropylacrylamide gel dosimeter

This study aimed to investigate dosimeter characteristics by using a photon beam with and without the flattening filter of intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) by using a 3D N-isopropylacrylamide (NIPAM) polymer gel. A self-developed optical computed tomography scheme was used to measure the dose distribution. Gamma evaluation was performed between the dose distribution calculated by a treatment planning system and the measured dose distribution by using the criteria of 3% dose difference and 3 mm distance to agreement. Under these criteria, the passing rates showed no significant difference between IMRT and VMAT irradiation with and without the flattening filter. All these results revealed that the NIPAM gel dosimeter was for high-dose-rate radiation and clinical-pretreatment verifications.

3D-Printed Hydrogel Capsule for Transporting Particles in Flow Channel

Droplet based microfluidics is used for cell culturing, protein crystallization, drug delivery and mixture chemical reagent. It enables quick and accurate analysis with a small amount of reagent. Usually, droplets containing particles are made by T-junction using organic phase and water phase. Sometimes researchers want to replace medium, recovery and reseal particles in droplets. However it is difficult due to surface tension and difficulty to process hydrogel. It has been a problem for many years. In addition, there is a need for a capsule having a function of carrying and releasing drugs and cells to an arbitrary position. We propose 3D-printed hydrogel capsule to solve these problems. We made 3D-printed hydrogel capsule with particles entrance. The entrance is closed by bubble. N-isopropylacrylamide (NIPA) gel was selected. It was prepared for 3D-printing. NIPA gel is famous for phase transition. It swells below 32.6℃ and shrinks above that. With this principle, we can transport particle to remove rid bubble at any place. The 3D-printer we used was ACCULAS BA-30H (DMEC). Evaluate systems were made up of microscopic, syringe pump and flow channel. Flow channel was made of Polydimethylsiloxane (PDMS) using 3D-printed mold.

Using an on-board cone-beam computed tomography scanner as an imaging modality for gel dosimetry: A feasibility study

On-board cone-beam computed tomography (CBCT) was used to scan the N-isopropylacrylamide (NIPAM) gel dosimeter. A dose-response curve from 1 to 12 Gy was created. The dose profile and depth dose curve were measured, and the dose distribution acquired from CBCT was then compared with that obtained from a treatment planning system (TPS). The linearity of the dose-response curve obtained by CBCT scanning of the NIPAM gel was 0.985. The mean percent standard deviation of various doses was 12.8%. A 12- to 24-h post-irradiation time was required to achieve stable CBCT readouts. Both dose profile and depth dose were in agreement with the results of TPS. The dose difference at the isocenter between CBCT and TPS was 3.8%. The gamma evaluation under the conditions of 5% dose difference and 5 mm distance-to-agreement was performed with the pass rate of 92.6%. These results indicate that an on-board CBCT can be used for scanning gel dosimeters in clinical radiotherapy.

Necklace-like microstructure in shallow-quenched aqueous solutions of poly(n-isopropylacrylamide), detected by advanced small-angle neutron scattering methods.

The microstructure of aqueous poly(N-isopropyl acrylamide) (PNIPA) gel and solution was investigated by small-angle neutron scattering (SANS) in the vicinity of the gel volume phase transition at TV (= 34 °C). The SANS technique was reinforced by refractive neutron lenses and perfect single crystals in order to get access to μm length scales. At 31 °C SANS shows Ornstein-Zernike (OZ) type scattering in the swollen gel which at 32 °C starts to deviate from the OZ-formalism, exhibiting excess scattering and at the wave number qc≅ 5 × 10-3Å-1 a crossover to Porod's asymptotic q-4 power law. For shallow quenches of ΔT < 1.0 K above TV the excess scattering intensity is further increasing whereas qc is shifting toward lower values. Based on this observation and analysis of the SANS q-profiles, we propose a necklace-like microstructure consisting of PNIPA-rich globules of R≅ 100 Å size which are connected by swollen PNIPA chains and stabilized for more than a day by pinning of chain connectivity. The formation of PNIPA globules near TV is discussed in terms of partially cooperative dehydration which is crucial to explain the "miscibility square phase behavior" of aqueous PNIPA solutions. Globule-like structure was also found in aqueous PNIPA solution of size slightly larger than in gels. At deeper quenches of gels above TV (ΔT > 1.0 K) the globules are aggregating to larger objects of R≅ 0.24 μm size as determined from a strong intensity upturn in the small q-region of USANS.

(Invited) Volume Phase Transition of NIPA Gels and Its Relation to the Inhomogeneity Caused by Extremely Multifunctional Crosslinker

Crosslinkers play essential role in determining physical properties of gels. Using cray substance, Laponite (Rockwood Additive Ltd, USA), as the crosslinker, we made N-isopropylacrylamide(NIPA) gels. We found, if we count one Laponite crystal as one crosslinker, that NIPA gels crosslinked with Laponite gelled at much lower fraction (1/2000) of crosslinker than the gel crosslinked with popular N,N’-methylenebisacrylamide(BIS). This result indicates that Laponite is extremely multifunctional crosslinker. Though the volume changes of the NIPA-Laponite gels were continuous one, the volume change itself was much larger than that of the NIPA-Bis gels, and we observed the hysteresis loop as well as the miner loops just like magnetic system. We will discuss about the possible mechanism of such hysteresis loops.

A systematic review of clinical applications of polymer gel dosimeters in radiotherapy

Radiotherapy has rapidly improved because of the use of new equipment and techniques. Hence, the appeal for a feasible and accurate three-dimensional (3D) dosimetry system has increased. In this regard, gel dosimetry systems are accurate 3D dosimeters with high resolution. This systematic review evaluates the clinical applications of polymer gel dosimeters in radiotherapy. To find the clinical applications of polymer gel dosimeters in radiotherapy, a full systematic literature search was performed on the basis of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines in electronic databases up to January 31, 2017, with use of search-related terms in the titles and abstracts of articles. A total of 765 articles were screened in accordance with our inclusion and exclusion criteria. Eventually, 53 articles were included in the study. The findings show that most clinical applications of polymer gel dosimeters relate to external radiotherapy. Most of the gel dosimeters studied have acceptable dose accuracy as a 3D dosimeter with high resolution. It is difficult to judge which is the best polymer gel dosimeter to use in a clinical setting, because each gel dosimeter has advantages and limitations. For example, methacrylic acid–based gel dosimeters have high dose sensitivity and low toxicity, while their dose response is beam energy dependent; in contrast, N-isopropylacrylamide gel dosimeters have low dose resolution, but their sensitivity is lower and they are relatively toxic.

(Invited) Anisotropic Self-Oscillating Reaction in Liquid Crystalline Nanosheets Hydrogels

Soft and wet structures with anisotropy and hierarchy are regarded as key for various intriguing functions and properties of living organisms. Liquid crystal (LC) materials are often utilized to artificially fabricate such sophisticated structures likeliving organisms. For this purpose, lyotropic LC phases of inorganic nanosheets are emerging as new type LC materialsdue to many fascinating characteristics. Actually, inorganic nanosheet LCs have been utilized as unusual anisotropic reaction media,the materials to fabricate tough fibers and inorganic-polymer composites. The most distinctive feature of inorganic nanosheet LCs is that they can effectively barrier the diffusion of molecules. Since the nanosheets are two dimensional objects with huge aspect ratio (the lateral dimension of several micrometer and the thickness of ~1 nm), aligned nanosheets can effectively retard molecular diffusion compared to the materials made with conventional LC molecules. We recently communicated that dye ions anisotropically diffuse into the polymer gel embedded with macroscopically aligned LC nanosheets.1 Meanwhile, combining artificial soft and wet structures with particular chemical reactions that have characteristic features of biological systems is fascinating because such combinations will lead us to fabrication of artificial living organisms or molecular robots. Yoshida et al. reported the hydrogel of poly(N-isopropylacrylamide) (pNIPA) copolymerized with ruthenium trisbipyridine (Ru(bpy)3) units, which is a catalyst of self-oscillating Belouzov-Zhabozinsky reaction (BZ-reaction)2. Not only BZ reaction proceeded in this gel, but also the gel showed self-oscillating motion. After this pioneering work, many kinds of self-oscillating gels with improved properties such as faster and larger oscillation, were reported in view of applications for micro-robotics and micro electro mechanical systems (MEMS). The concentric circlesor rotating spiral waves that appear during BZ reaction is also interesting phenomena as a model of chemical waves in biological systemssuch as embryo, neural networks, and heart muscles. In this context, controlling and modifying the wave patterns in anisotropic, heterogeneous, or patterned media are interested. The BZ-reactions under electric field, in the lamellar phase of surfactant solution and in a porous glass were investigated to control the reaction. However, anisotropic BZ reaction has not been investigated so far. In this study3, anisotropic chemical wave propagation of self-oscillating Belouzov-Zhabozinsky (BZ) reaction was demonstrated in the poly(N-isopropylacrylamide gel films embedded with macroscopically aligned liquid crystalline inorganic nanosheets. While the average propagation rate of chemical wave was 3.56 mm min-1in the gels without nanosheets, the propagation was retarded in the gels with 1 wt% of nanosheets: v//= 1.89 mm min-1and v⊥= 1.33 mm min-1along the direction parallel and perpendicular to the nanosheet planes, respectively. Thus, the wave propagation is anisotropic with the anisotropy ratio v// / v⊥= 1.42 in these gels and the periodic patterns formed by the BZ-reaction were concentric ellipses, different from circles seen in isotropic gels. Furthermore, the propagation rate and degree of anisotropy were controllable by nanosheet concentration. These phenomena can be explained that the diffusion of molecules inside the gel is effectively hindered along the direction perpendicular to the nanosheet planes due to very large aspect ratio of the aligned nanosheets.The present systems will be applicable for anisotropic self-oscillating soft actuators with one-dimensional motions as well as for ideal model system of BZ reactions. Acknowledgement This research was supported by: Research Center for Materials and Energy Devices of Fukuoka Institute of Technology (FIT-ME) (Strategic Research Foundation Grant-Aided Project for Private University from MEXT; #S1511036L); KAKENHI (#24104005, #15K05657, and #17H03209); Canon Foundation; Network Joint Research Center for Materials and Devices (#201507 and #20166009); and Electronics Research Laboratory of Fukuoka Institute of Technology.

Application of bi-nanoparticle on dose enhancement effect in two different polymer gel dosimeter using spectrophotometer.

This study aimed at proving the ability of bismuth-nanoparticle (Bi-np) in dose enhancement effect (DEE) using the polymer gel dosimeter. Two different polymer gels, namely poly acrylamide gelatin tetrakis hydroxymethyl phosphonium chloride (PAGAT) and N-isopropylacrylamide (NIPAM) gels were chosen for this study. The gels were doped with Bi-np particle with various concentrations of 0.5 mM, 1 mM, and 2.5 mM and were then irradiated with a CO-60 gamma radiation source of energy 1.25 MeV. Gel samples were analyzed by spectrophotometer. The dose enhancement factor (DEF) was calculated for both gels for all concentrations of Bi-np particle. The higher DEF for PAGAT and NIPAM was calculated as 1.3415 and 1.1823, respectively, for 0.5 mM concentration of Bi-np. From our results, we infer that 0.5 mM is the optimal concentration in polymer gel to obtain good DEEs in the energy range of 1.25 MeV.

Extraction and recovery of soft metal ion by porous silica coated by hydrophilic polymer gel with hexavalent nitrogen-donor ligand

ABSTRACTA hydrophilic N-isopropylacrylamide (NIPA) gel copolymerized with a hexavalent nitrogen donor ligand, N,N,N’,N’-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine (TPPEN), adsorbs soft metals selectively from the acidic aqueous phase. We are developing porous silica particles coating the TPPEN-NIPA gel with high TPPEN content thinly on the pore surface of porous silica by a new gel-coating method using surface tension. Half of the pore volume of the silica particles remained by the coating of the TPPEN-NIPA gel with the high TPPEN content of 30 mol%. A large separation factor (SF) of Cd(II)/Eu(III) of 60 was observed at pH 2. The proposed chromatographic agent with the high TPPEN content is applicable for practical use.

Improving cracking resistance of cement mortar by thermo-sensitive poly N-isopropyl acrylamide (PNIPAM) gels

Cracking problems are threats to durability and sustainability of high performance cement-based composites. Due to the complex behaviors of cement materials under various environmental conditions, accurate prediction of the cracks is very difficult. In this work, effects of noval thermo-sensitive polymer N-isopropylacrylamide (PNIPAM) on the cracking resistance of cement mortar were investigated. The micro structures of cement mortar and PNIPAM were characterized by environmental scanning electron microscopy (ESEM) and Fourier Transform Infrared Spectoscopy (FT-IR). The pulse velocity, water absorption and water content of cement mortar were tested to observe the inner structure changes of cement mortar with PNIPAM. Artificial neural network (ANN) technology was used to predict the cracking resistance of cement mortar with PNIPAM. The results show that PNIPAM is cross-linked macromolecule polymer with special thermo-sensitive characters of shrinkage at high temperature and expansion at low temperature. When the mixing temperature is lower than LCST of PNIPAM, it can expand and is soluble in water. However, PNIPAM can shrink and release water to cure the hardened mortar when temperature is higher than LCST due to the cement hydration heat accumulation. The proposed model built by ANN can be used to predict the cracking resistance of cement mortar. The model was further applied to evaluate the effects of different PNIPAM contents on the cracking performance of cement mortar. PNIPAM with suitable contents can decrease the internal deflects of cement mortar. The content of PNIPAM can be used below 1.2% of cement mass for the consideration of cracking resistance improvement of cement mortar.